Experiment in Physics (Stanford Encyclopedia of Philosophy) Cite this entry Search the SEP • Advanced Search • Tools • RSS FeedTable of Contents• What's New• Archives• Projected ContentsEditorial Information• About the SEP• Editorial Board• How to Cite the SEP• Special CharactersSupport the SEPContact the SEP ©Metaphysics Research Lab,CSLI,Stanford University  Open access to the SEP is made possible by a world-wide funding initiative. Please Read How You Can Help Keep the Encyclopedia FreeExperiment in PhysicsFirst published Mon Oct 5, 1998; substantive revision Fri Jul 6, 2007Physics, and natural science in general, is a reasonable enterprisebased on valid experimental evidence, criticism, and rationaldiscussion. It provides us with knowledge of the physical world, and itis experiment that provides the evidence that grounds this knowledge.Experiment plays many roles in science. One of its important roles isto test theories and to provide the basis for scientific knowledge.[1] It can also call for a new theory, either byshowing that an accepted theory is incorrect, or by exhibiting a newphenomenon that is in need of explanation. Experiment can provide hintstoward the structure or mathematical form of a theory and it canprovide evidence for the existence of the entities involved in ourtheories. Finally, it may also have a life of its own, independent oftheory. Scientists may investigate a phenomenon just because it looksinteresting. Such experiments may provide evidence for a future theoryto explain. [Examples of these different roles will be presentedbelow.] As we shall see below, a single experiment may play several ofthese roles at once.If experiment is to play these important roles in science then wemust have good reasons to believe experimental results, for science isa fallible enterprise. Theoretical calculations, experimental results,or the comparison between experiment and theory may all be wrong.Science is more complex than "The scientist proposes, Nature disposes."It may not always be clear what the scientist is proposing. Theoriesoften need to be articulated and clarified. It also may not be clearhow Nature is disposing. Experiments may not always give clear-cutresults, and may even disagree for a time.In what follows, the reader will find an epistemology of experiment,a set of strategies that provides reasonable belief in experimentalresults. Scientific knowledge can then be reasonably based on theseexperimental results.I. Experimental Results A. The Case For Learning From Experiment 1. An Epistemology of Experiment 2. Galison's Elaboration B. The Case Against Learning From Experiment 1. Collins and the Experimenters' Regress 2. Pickering on Communal Opportunism and Plastic Resources 3. Critical Responses to Pickering 4. Pickering and the Dance of Agency 5. Hacking's "Social Construction of What?" II. The Roles of Experiment A. A Life of Its Own B. Confirmation and Refutation 1. The Discovery of Parity Nonconservation: A Crucial Experiment 2. The Discovery of CP Violation: A Persuasive Experiment 3. The Discovery of Bose-Einstein Condensation: Confirmation After 70 Years C. Complications 1. The Fall of the Fifth Force 2. Right Experiment, Wrong Theory: the Stern Gerlach Experiment 3. Sometimes Refutation Doesn't Work: The Double Scattering of Electrons D. Other Roles 1. Evidence for a New Entity: J.J. Thomson and the Electron 2. The Articulation of Theory: Weak Interactions E. Some Thoughts on Experiment in Biology 1. Epistemologoical Strategies and the Peppered Moth Experiment 2. The Meselson-Stahl Experiment: “The Most Beautiful Experiment in Biology” III. ConclusionBibliographyOther Internet ResourcesRelated EntriesI. Experimental ResultsA. The Case For Learning From Experiment1. An Epistemology of ExperimentIt has been two decades since Ian Hacking asked, "Do we see through amicroscope?" (Hacking 1981). Hacking's question really asked how do wecome to believe in an experimental result obtained with a complexexperimental apparatus? How do we distinguish between a valid result[2] and an artifact created by that apparatus?If experiment is to play all of the important roles in sciencementioned above and to provide the evidential basis for scientificknowledge, then we must have good reasons to believe in those results.Hacking provided an extended answer in the second half ofRepresenting and Intervening (1983). He pointed out that eventhough an experimental apparatus is laden with, at the very least, thetheory of the apparatus, observations remain robust despite changes inthe theory of the apparatus or in the theory of the phenomenon. Hisillustration was the sustained belief in microscope images despite themajor change in the theory of the microscope when Abbe pointed out theimportance of diffraction in its operation. One reason Hacking gave forthis is that in making such observations the experimentersintervened--they manipulated the object under observation. Thus, inlooking at a cell through a microscope, one might inject fluid into thecell or stain the specimen. One expects the cell to change shape orcolor when this is done. Observing the predicted effect strengthens ourbelief in both the proper operation of the microscope and in theobservation. This is true in general. Observing the predicted effect ofan intervention strengthens our belief in both the proper operation ofthe experimental apparatus and in the observations made with it. Hacking also discussed the strengthening of one's belief in anobservation by independent confirmation. The fact that the same patternof dots--dense bodies in cells--is seen with "different" microscopes,(e.g. ordinary, polarizing, phase-contrast, fluorescence, interference,electron, acoustic etc.) argues for the validity of the observation.One might question whether "different" is a theory-laden term. Afterall, it is our theory of light and of the microscope that allows us toconsider these microscopes as different from each other. Nevertheless,the argument holds. Hacking correctly argues that it would be apreposterous coincidence if the same pattern of dots were produced intwo totally different kinds of physical systems. Different apparatuseshave different backgrounds and systematic errors, making thecoincidence, if it is an artifact, most unlikely. If it is a correctresult, and the instruments are working properly, the coincidence ofresults is understandable.Hacking's answer is correct as far as it goes. It is, however,incomplete. What happens when one can perform the experiment with onlyone type of apparatus, such as an electron microscope or a radiotelescope, or when intervention is either impossible or extremelydifficult? Other strategies are needed to validate the observation.[3] These may include:1) Experimental checks and calibration, in which theexperimental apparatus reproduces known phenomena. For example, if wewish to argue that the spectrum of a substance obtained with a new typeof spectrometer is correct, we might check that this new spectrometercould reproduce the known Balmer series in hydrogen. If we correctlyobserve the Balmer Series then we strengthen our belief that thespectrometer is working properly. This also strengthens our belief inthe results obtained with that spectrometer. If the check fails then wehave good reason to question the results obtained with that apparatus. 2) Reproducing artifacts that are known in advance to be present. Anexample of this comes from experiments to measure the infrared spectraof organic molecules (Randall et al. 1949). It was not always possibleto prepare a pure sample of such material. Sometimes the experimentershad to place the substance in an oil paste or in solution. In suchcases, one expects to observe the spectrum of the oil or the solvent,superimposed on that of the substance. One can then compare thecomposite spectrum with the known spectrum of the oil or the solvent.Observation then of this artifact gives confidence in othermeasurements made with the spectrometer.3) Elimination of plausible sources of error and alternativeexplanations of the result (the Sherlock Holmes strategy).[4] Thus, whenscientists claimed to have observed electric discharges in the rings ofSaturn, they argued for their result by showing that it could not havebeen caused by defects in the telemetry, interaction with theenvironment of Saturn, lightning, or dust. The only remainingexplanation of their result was that it was due to electric dischargesin the rings--there was no other plausible explanation of theobservation. (In addition, the same result was observed by both Voyager1 and Voyager 2. This provided independent confirmation. Often, severalepistemological strategies are used in the same experiment.)4) Using the results themselves to argue for their validity.Consider the problem of Galileo's telescopic observations of the moonsof Jupiter. Although one might very well believe that his primitive,early telescope might have produced spurious spots of light, it isextremely implausible that the telescope would create images that theywould appear to be a eclipses and other phenomena consistent with themotions of a small planetary system. It would have been even moreimplausible to believe that the created spots would satisfy Kepler'sThird Law (R3/T2 = constant). A similar argumentwas used by Robert Millikan to support his observation of thequantization of electric charge and his measurement of the charge ofthe electron. Millikan remarked, "The total number of changes which wehave observed would be between one and two thousand, and in not onesingle instance has there been any change which did not represent theadvent upon the drop of one definite invariable quantity of electricityor a very small multiple of that quantity"(Millikan 1911, p. 360).In both of these cases one is arguing that there was no plausiblemalfunction of the apparatus, or background, that would explain theobservations.5) Using an independently well-corroborated theory of the phenomenato explain the results. This was illustrated in the discovery of theW±, the charged intermediate vector boson required bythe Weinberg-Salam unified theory of electroweak interactions. Althoughthese experiments used very complex apparatuses and used otherepistemological strategies (for details see (Franklin 1986, pp.170-72)) I believe that the agreement of the observations with thetheoretical predictions of the particle properties helped to validatethe experimental results. In this case the particle candidates wereobserved in events that contained an electron with high transversemomentum and in which there were no particle jets, just as predicted bythe theory. In addition, the measured particle mass of 81 ± 5GeV/c2 and 80+10-6,GeV/c2, found in the two experiments (note theindependent confirmation also), was in good agreement with thetheoretical prediction of 82 ± 2.4 GeV/c2. It wasvery improbable that any background effect, which might mimic thepresence of the particle, would be in agreement with theory.6) Using an apparatus based on a well-corroborated theory. In thiscase the support for the theory inspires confidence in the apparatusbased on that theory. This is the case with the electron microscope andthe radio telescope, whose operations are based on a well-supportedtheories, although other strategies are also used to validate theobservations made with these instruments.7) Using statistical arguments. An interesting example of this arosein the 1960s when the search for new particles and resonances occupieda substantial fraction of the time and effort of those physicistsworking in experimental high-energy physics. The usual technique was toplot the number of events observed as a function of the invariant massof the final-state particles and to look for bumps above a smoothbackground. The usual informal criterion for the presence of a newparticle was that it resulted in a three standard-deviation effectabove the background, a result that had a probability of 0.27% ofoccurring in a single bin. This criterion was later changed to fourstandard deviations, which had a probability of 0.0064% when it waspointed out that the number of graphs plotted each year by high-energyphysicists made it rather probable, on statistical grounds, that athree standard-deviation effect would be observed.These strategies along with Hacking's intervention and independentconfirmation constitute an epistemology of experiment. They provide uswith good reasons for belief in experimental results, They do not,however, guarantee that the results are correct. There are manyexperiments in which these strategies are applied, but whose resultsare later shown to be incorrect (examples will be presented below).Experiment is fallible. Neither are these strategies exclusive orexhaustive. No single one of them, or fixed combination of them,guarantees the validity of an experimental result. Physicists use asmany of the strategies as they can conveniently apply in any givenexperiment. 2. Galison's ElaborationIn How Experiments End (1987), Peter Galison extended thediscussion of experiment to more complex situations. In his historiesof the measurements of the gyromagnetic ratio of the electron, thediscovery of the muon, and the discovery of weak neutral currents, heconsidered a series of experiments measuring a single quantity, a setof different experiments culminating in a discovery, and two high-energy physics experiments performed by large groups with complexexperimental apparatus. Galison's view is that experiments end when the experimentersbelieve that they have a result that will stand up in court--a resultthat I believe includes the use of the epistemological strategiesdiscussed earlier. Thus, David Cline, one of the weak neutral-currentexperimenters remarked, "At present I don't see how to make theseeffects [the weak neutral current event candidates] go away" (Galison,1987, p. 235).Galison emphasizes that, within a large experimental group,different members of the group may find different pieces of evidencemost convincing. Thus, in the Gargamelle weak neutral currentexperiment, several group members found the single photograph of aneutrino-electron scattering event particularly important, whereas forothers the difference in spatial distribution between the observedneutral current candidates and the neutron background was decisive.Galison attributes this, in large part, to differences in experimentaltraditions, in which scientists develop skill in using certain types ofinstruments or apparatus. In particle physics, for example, there isthe tradition of visual detectors, such as the cloud chamber or thebubble chamber, in contrast to the electronic tradition of Geiger andscintillation counters and spark chambers. Scientists within the visualtradition tend to prefer "golden events" that clearly demonstrate thephenomenon in question, whereas those in the electronic tradition tendto find statistical arguments more persuasive and important thanindividual events. (For further discussion of this issue see Galison(1997)).Galison points out that major changes in theory and in experimentalpractice and instruments do not necessarily occur at the same time.This persistence of experimental results provides continuity acrossthese conceptual changes. Thus, the experiments on the gyromagneticratio spanned classical electromagnetism, Bohr's old quantum theory,and the new quantum mechanics of Heisenberg and Schrodinger. RobertAckermann has offered a similar view in his discussion of scientificinstruments.The advantages of a scientific instrument are that itcannot change theories. Instruments embody theories, to be sure, or wewouldn't have any grasp of the significance of theiroperation….Instruments create an invariant relationship betweentheir operations and the world, at least when we abstract from theexpertise involved in their correct use. When our theories change, wemay conceive of the significance of the instrument and the world withwhich it is interacting differently, and the datum of an instrument maychange in significance, but the datum can nonetheless stay the same,and will typically be expected to do so. An instrument reads 2 whenexposed to some phenomenon. After a change in theory,[5] it willcontinue to show the same reading, even though we may take the readingto be no longer important, or to tell us something other than what wethought originally (Ackermann 1985, p. 33).Galison also discusses other aspects of the interaction betweenexperiment and theory. Theory may influence what is considered to be areal effect, demanding explanation, and what is considered background.In his discussion of the discovery of the muon, he argues that thecalculation of Oppenheimer and Carlson, which showed that showers wereto be expected in the passage of electrons through matter, left thepenetrating particles, later shown to be muons, as the unexplainedphenomenon. Prior to their work, physicists thought the showeringparticles were the problem, whereas the penetrating particles seemed tobe understood.The role of theory as an "enabling theory," (i.e., one that allowscalculation or estimation of the size of the expected effect and alsothe size of expected backgrounds) is also discussed by Galison. (Seealso (Franklin 1995b) and the discussion of the Stern-Gerlachexperiment below). Such a theory can help to determine whether anexperiment is feasible. Galison also emphasizes that elimination ofbackground that might simulate or mask an effect is central to theexperimental enterprise, and not a peripheral activity. In the case ofthe weak neutral current experiments, the existence of the currentsdepended crucially on showing that the event candidates could not allbe due to neutron background.[6]There is also a danger that the design of an experiment may precludeobservation of a phenomenon. Galison points out that the originaldesign of one of the neutral current experiments, which included a muontrigger, would not have allowed the observation of neutral currents. Inits original form the experiment was designed to observe chargedcurrents, which produce a high energy muon. Neutral currents do not.Therefore, having a muon trigger precluded their observation. Onlyafter the theoretical importance of the search for neutral currents wasemphasized to the experimenters was the trigger changed. Changing thedesign did not, of course, guarantee that neutral currents would beobserved.Galison also shows that the theoretical presuppositions of theexperimenters may enter into the decision to end an experiment andreport the result. Einstein and de Haas ended their search forsystematic errors when their value for the gyromagnetic ratio of theelectron, g = 1, agreed with their theoretical model oforbiting electrons. This effect of presuppositions might cause one tobe skeptical of both experimental results and their role in theoryevaluation. Galison's history shows, however, that, in this case, theimportance of the measurement led to many repetitions of themeasurement. This resulted in an agreed-upon result that disagreed withtheoretical expectations.Recently, Galison has modified his views. In Image andLogic, an extended study of instrumentation in 20th-centuryhigh-energy physics, Galison (1997) has extended his argument thatthere are two distinct experimental traditions within that field--thevisual (or image) tradition and the electronic (or logic) tradition.The image tradition uses detectors such as cloud chambers or bubblechanbers, which provide detailed and extensive information about eachindividual event. The electronic detectors used by the logic tradition,such as geiger counters, scintillation counters, and spark chambers,provide less detailed information about individual events, but detectmore events. Galison's view is that experimenters working in these twotraditions form distinct epistemic and linguistic groups that rely ondifferent forms of argument. The visual tradition emphasizes the single"golden" event. "On the image side resides a deep-seated commitment tothe ‘golden event’: the single picture of such clarity and distinctnessthat it commands acceptance." (Galison, 1997, p. 22) "The golden eventwas the exemplar of the image tradition: an individual instance socomplete and well defined, so ‘manifestly’ free of distortion andbackground that no further data had to be involved" (p. 23). Becausethe individual events provided in the logic detectors containded lessdetailed information than the pictures of the visual tradition,statistical arguments based on large numbers of events wererequired.Kent Staley (1999) disagrees. He argues that the two traditions arenot as distinct as Galison believes:I show that discoveries in both traditions have employedthe same statistical [I would add "and/or probabilistic"] form ofargument, even when basing discovery claims on single, golden events.Where Galison sees an epistemic divide between two communities that canonly be bridged by creole- or pidgin-like ‘interlanguage,’ there is infact a shared commitment to a statistical form of experimentalargument. (P. 96).Staley believes that although there is certainly epistemiccontinuity within a given tradition, there is also a continuity betweenthe traditions. This does not, I believe, mean that the sharedcommitmeny comprises all of the arguments offered in any particularinstance, but rather that the same methods are often used by bothcommunities. Galison does not deny that statistical methods are used inthe image tradition, but he thinks that they are relativelyunimportant. "While statistics could certainly be used within the imagetradition, it was by no means necessary for most applications"(Galison, 1997, p. 451). In contrast, Galison believes that argumentsin the logic tradition "were inherently and inalienably statistical.Estimation of probable errors and the statistical excess overbackground is not a side issue in these detectors--it is central to thepossibilty of any demonstration at all" (p. 451).Although a detailed discussion of the disagreement between Staleyand Galison would take us too far from the subject of this essay, theyboth agree that arguments are offered for the correctness ofexperimental results. Their disagreement concerns the nature of thosearguments. (For further discussion see Franklin, (2002), pp. 9-17).B. The Case Against Learning From Experiment1. Collins and the Experimenters' RegressCollins, Pickering, and others, have raised objections to the view thatexperimental results are accepted on the basis of epistemologicalarguments. They point out that "a sufficiently determined critic canalways find a reason to dispute any alleged ‘result’"(MacKenzie 1989, p. 412). Harry Collins, for example, is well known forhis skepticism concerning both experimental results and evidence. Hedevelops an argument that he calls the "experimenters' regress"(Collins 1985, chapter 4, pp. 79-111): What scientists take to be acorrect result is one obtained with a good, that is, properlyfunctioning, experimental apparatus. But a good experimental apparatusis simply one that gives correct results. Collins claims that there areno formal criteria that one can apply to decide whether or not anexperimental apparatus is working properly. In particular, he arguesthat calibrating an experimental apparatus by using a surrogate signalcannot provide an independent reason for considering the apparatus tobe reliable. In Collins' view the regress is eventually broken by negotiationwithin the appropriate scientific community, a process driven byfactors such as the career, social, and cognitive interests of thescientists, and the perceived utility for future work, but one that isnot decided by what we might call epistemological criteria, or reasonedjudgment. Thus, Collins concludes that his regress raises seriousquestions concerning both experimental evidence and its use in theevaluation of scientific hypotheses and theories. Indeed, if no way outof the regress can be found, then he has a point.Collins strongest candidate for an example of the experimenters'regress is presented in his history of the early attempts to detectgravitational radiation, or gravity waves. (For more detaileddiscussion of this episode see (Collins 1985; 1994; Franklin 1994;1997a) In this case, the physics community was forced to compareWeber's claims that he had observed gravity waves with the reports fromsix other experiments that failed to detect them. On the one hand,Collins argues that the decision between these conflicting experimentalresults could not be made on epistemological or methodologicalgrounds--he claims that the six negative experiments could notlegitimately be regarded as replications[7] and hence become lessimpressive. On the other hand, Weber's apparatus, precisely because theexperiments used a new type of apparatus to try to detect a hithertounobserved phenomenon,[8] could not be subjected to standardcalibration techniques.The results presented by Weber's critics were not only morenumerous, but they had also been carefully cross-checked. The groupshad exchanged both data and analysis programs and confirmed theirresults. The critics had also investigated whether or not theiranalysis procedure, the use of a linear algorithm, could account fortheir failure to observe Weber's reported results. They had usedWeber's preferred procedure, a nonlinear algorithm, to analyze theirown data, and still found no sign of an effect. They had alsocalibrated their experimental apparatuses by inserting acoustic pulsesof known energy and finding that they could detect a signal. Weber, onthe other hand, as well as his critics using his analysis procedure,could not detect such calibration pulses.There were, in addition, several other serious questions raisedabout Weber's analysis procedures. These included an admittedprogramming error that generated spurious coincidences between Weber'stwo detectors, possible selection bias by Weber, Weber's report ofcoincidences between two detectors when the data had been taken fourhours apart, and whether or not Weber's experimental apparatus couldproduce the narrow coincidences claimed.It seems clear that the critics' results were far more credible thanWeber's. They had checked their results by independent confirmation,which included the sharing of data and analysis programs. They had alsoeliminated a plausible source of error, that of the pulses being longerthan expected, by analyzing their results using the nonlinear algorithmand by explicitly searching for such long pulses.[9] They had also calibratedtheir apparatuses by injecting pulses of known energy and observing theoutput.Contrary to Collins, I believe that the scientific community made areasoned judgment and rejected Weber's results and accepted those ofhis critics. Although no formal rules were applied (e.g. if you makefour errors, rather than three, your results lack credibility; or ifthere are five, but not six, conflicting results, your work is stillcredible) the procedure was reasonable.Pickering has argued that the reasons for accepting results are thefuture utility of such results for both theoretical and experimentalpractice and the agreement of such results with the existing communitycommitments. In discussing the discovery of weak neutral currents,Pickering states,Quite simply, particle physicists accepted the existence ofthe neutral current because they could see how to ply their trade moreprofitably in a world in which the neutral current was real. (1984b, p.87) Scientific communities tend to reject data that conflict with groupcommitments and, obversely, to adjust their experimental techniques totune in on phenomena consistent with those commitments. (1981, p.236)The emphasis on future utility and existing commitments is clear. Thesetwo criteria do not necessarily agree. For example, there are episodesin the history of science in which more opportunity for future work isprovided by the overthrow of existing theory. (See, for example, thehistory of the overthrow of parity conservation and of CP symmetrydiscussed below and in (Franklin 1986, Ch. 1, 3)). 2. Pickering on Communal Opportunism and Plastic ResourcesPickering has recently offered a different view of experimentalresults. In his view the material procedure (including the experimentalapparatus itself along with setting it up, running it, and monitoringits operation), the theoretical model of that apparatus, and thetheoretical model of the phenomena under investigation are all plasticresources that the investigator brings into relations of mutualsupport. (Pickering 1987; Pickering 1989). He says: Achieving such relations of mutual support is, I suggest,the defining characteristic of the successful experiment. (1987, p.199)He uses Morpurgo's search for free quarks, or fractional charges of 1/3e or 2/3 e, where e is the charge of theelectron. (See also (Gooding 1992)). Morpurgo used a modernMillikan-type apparatus and initially found a continuous distributionof charge values. Following some tinkering with the apparatus, Morpurgofound that if he separated the capacitor plates he obtained onlyintegral values of charge. "After some theoretical analysis, Morpurgoconcluded that he now had his apparatus working properly, and reportedhis failure to find any evidence for fractional charges" (Pickering1987, p. 197). Pickering goes on to note that Morpurgo did not tinker with the twocompeting theories of the phenomena then on offer, those of integraland fractional charge:The initial source of doubt about the adequacy of the earlystages of the experiment was precisely the fact that theirfindings--continuously distributed charges--were consonant with neitherof the phenomenal models which Morpurgo was prepared to countenance.And what motivated the search for a new instrumental model wasMorpurgo's eventual success in producing findings in accordance withone of the phenomenal models he was willing to accept The conclusion of Morpurgo's first series of experiments, then, andthe production of the observation report which they sustained, wasmarked by bringing into relations of mutual support of the threeelements I have discussed: the material form of the apparatus and thetwo conceptual models, one instrumental and the other phenomenal.Achieving such relations of mutual support is, I suggest, the definingcharactersitic of the successful experiment. (P. 199)Pickering has made several important and valid points concerningexperiment. Most importantly, he has emphasized that an experimentalapparatus is initially rarely capable of producing a valid experimentalresults and that some adjustment, or tinkering, is required before itdoes. He has also recognized that both the theory of the apparatus andthe theory of the phenomena can enter into the production of a validexperimental result. What I wish to question, however, is the emphasishe places on these theoretical components. From Millikan onwards,experiments had strongly supported the existence of a fundamental unitof charge and charge quantization. The failure of Morpurgo's apparatusproduce measurements of integral charge indicated that it was notoperating properly and that his theoretical understanding of it wasfaulty. It was the failure to produce measurements in agreement withwhat was already known (i.e., the failure of an important experimentalcheck) that caused doubts about Morpurgo's measurements. This was trueregardless of the theoretical models available, or those that Morpurgowas willing to accept. It was only when Morpurgo's apparatus couldreproduce known measurements that it could be trusted and used tosearch for fractional charge. To be sure, Pickering has allowed a rolefor the natural world in the production of the experimental result, butit does not seem to be decisive.3. Critical Responses to PickeringAckermann has offered a modification of Pickering's view. He suggeststhat the experimental apparatus itself is a less plastic resource theneither the theoretical model of the apparatus or that of thephenomenon. To repeat, changes in A [the apparatus] can often be seen(in real time, without waiting for accommodation by B [the theoreticalmodel of the apparatus]) as improvements, whereas‘improvements’ in B don't begin to count unless A isactually altered and realizes the improvements conjectured. It'sconceivable that this small asymmetry can account, ultimately, forlarge scale directions of scientific progress and for the objectivityand rationality of those directions. (Ackermann 1991, p.456)Hacking (1992) has also offered a more complex version ofPickering's later view. He suggests that the results of maturelaboratory science achieve stability and are self-vindicating when theelements of laboratory science are brought into mutual consistency andsupport. These are (1) ideas: questions, background knowledge,systematic theory, topical hypotheses, and modeling of the apparatus;(2) things: target, source of modification, detectors, tools, and datagenerators; and (3) marks and the manipulation of marks: data, dataassessment, data reduction, data analysis, and interpretation.Stable laboratory science arises when theories andlaboratory equipment evolve in such a way that they match each otherand are mutually self-vindicating. (1992, p. 56) We invent devices that produce data and isolate or create phenomena,and a network of different levels of theory is true to these phenomena.Conversely we may in the end count them only as phenomena only when thedata can be interpreted by theory. (pp. 57-8)One might ask whether such mutual adjustment between theory andexperimental results can always be achieved? What happens when anexperimental result is produced by an apparatus on which several of theepistemological strategies, discussed earlier, have been successfullyapplied, and the result is in disagreement with our theory of thephenomenon? Accepted theories can be refuted. Several examples will bepresented below. Hacking himself worries about what happens when a laboratory sciencethat is true to the phenomena generated in the laboratory, thanks tomutual adjustment and self-vindication, is successfully applied to theworld outside the laboratory. Does this argue for the truth of thescience. In Hacking's view it does not. If laboratory science doesproduce happy effects in the "untamed world,… it is not thetruth of anything that causes or explains the happy effects" (1992, p.60).4. Pickering and the Dance of AgencyRecently Pickering has offered a somewhat revised account of science."My basic image of science is a performative one, in which theperformances the doings of human and material agency come to the fore.Scientists are human agents in a field of material agency which theystruggle to capture in machines (Pickering, 1995, p. 21)." He thendiscusses the complex interaction between human and material agency,which I interpret as the interaction between experimenters, theirapparatus, and the natural world. The dance of agency, seen asymmetrically from the humanend, thus takes the form of a dialectic of resistance andaccommodations, where resistance denotes the failure to achieve anintended capture of agency in practice, and accommodation an activehuman strategy of response to resistance, which can include revisionsto goals and intentions as well as to the material form of the machinein question and to the human frame of gestures and social relationsthat surround it (p. 22)."Pickering's idea of resistance is illustrated by Morpurgo'sobservation of continuous, rather than integral or fractional,electrical charge, which did not agree with his expectations.Morpurgo's accommodation consisted of changing his experimentalapparatus by using a larger separation between his plates, and also bymodifying his theoretical account of the apparatus. That being done,integral charges were observed and the result stabilized by the mutualagreement of the apparatus, the theory of the apparatus, and the theoryof the phenomenon. Pickering notes that "the outcomes depend on how theworld is (p. 182)." "In this way, then, how the material worldis leaks into and infects our representations of it in anontrivial and consequential fashion. My analysis thus displays anintimate and responsive engagement between scientific knowledge and thematerial world that is integral to scientific practice (p. 183)."Nevertheless there is something confusing about Pickering'sinvocation of the natural world. Although Pickering acknowledges theimportance of the natural world, his use of the term "infects" seems toindicate that he isn't entirely happy with this. Nor does the naturalworld seem to have much efficacy. It never seems to be decisive in anyof Pickering's case studies. Recall that he argued that physicistsaccepted the existence of weak neutral currents because "they could plytheir trade more profitably in a world in which the neutral current wasreal." In his account, Morpurgo's observation of continuous charge isimportant only because it disagrees with his theoretical models of thephenomenon. The fact that it disagreed with numerous previousobservations of integral charge doesn't seem to matter. This is furtherillustrated by Pickering's discussion of the conflict between Morpurgoand Fairbank. As we have seen, Morpurgo reported that he did notobserve fractional electrical charges. On the other hand, in the late1970s and early 1980s, Fairbank and his collaborators published aseries of papers in which they claimed to have observed fractionalcharges (See, for example, LaRue, Phillips et al. 1981 ). Faced withthis discord Pickering concludes,In Chapter 3, I traced out Morpurgo's route to his findingsin terms of the particular vectors of cultural extension that hepursued, the particular resistances and accommodations thusprecipitated, and the particular interactive stabilizations heachieved. The same could be done, I am sure, in respect of Fairbank.And these tracings are all that needs to said about their divergence.It just happened that the contingencies of resistance and accommodationworked out differently in the two instances. Differences like theseare, I think, continually bubbling up in practice, without any specialcauses behind them (pp. 211-212).The natural world seems to have disappeared from Pickering'saccount. There is a real question here as to whether or not fractionalcharges exist in nature. The conclusions reached by Fairbank and byMorpurgo about their existence cannot both be correct. It seemsinsufficient to merely state, as Pickering does, that Fairbank andMorpurgo achieved their individual stabilizations and to leave theconflict unresolved. (Pickering does comment that one could follow thesubsequent history and see how the conflict was resolved, and he doesgive some brief statements about it, but its resolution is notimportant for him). At the very least, I believe, one should considerthe actions of the scientific community. Scientific knowledge is notdetermined individually, but communally. Pickering seems to acknowledgethis. "One might, therefore, want to set up a metric and say that itemsof scientific knowledge are more or less objective depending on theextent to which they are threaded into the rest of scientific culture,socially stabilized over time, and so on. I can see nothing wrong withthinking this way…. (p. 196)." The fact that Fairbank believedin the existence of fractional electrical charges, or that Weberstrongly believed that he had observed gravity waves, does not makethem right. These are questions about the natural world that can beresolved. Either fractional charges and gravity waves exist or theydon't, or to be more cautious we might say that we have good reasons tosupport our claims about their existence, or we do not.Another issue neglected by Pickering is the question of whether aparticular mutual adjustment of theory, of the apparatus or thephenomenon, and the experimental apparatus and evidence is justified.Pickering seems to believe that any such adjustment that providesstabilization, either for an individual or for the community, isacceptable. I do not. Experimenters sometimes exclude data and engagein selective analysis procedures in producing experimental results.These practices are, at the very least, questionable as is the use ofthe results produced by such practices in science. There are, Ibelieve, procedures in the normal practice of science that providesafeguards against them. (For details see Franklin, 2002, Section1).The difference between our attitudes toward the resolution ofdiscord is one of the important distinctions between my view of scienceand Pickering's. I do not believe it is sufficient simply to say thatthe resolution is socially stabilized. I want to know how thatresolution was achieved and what were the reasons offered for thatresolution. If we are faced with discordant experimental results andboth experimenters have offered reasonable arguments for theircorrectness, then clearly more work is needed. It seems reasonable, insuch cases, for the physics community to search for an error in one, orboth, of the experiments.Pickering discusses yet another difference between our views. Hesees traditional philosophy of science as regarding objectivity "asstemming from a peculiar kind of mental hygiene or policing of thought.This police function relates specifically to theory choice in science,which,… is usually discussed in terms of the rational rules ormethods responsible for closure in theoretical debate (p. 197)." Hegoes on to remark that,The most action in recent methodological thought hascentered on attempts like Allan Franklin's to extend the methodologicalapproach to experiments by setting up a set of rules for their properperformance. Franklin thus seeks to extend classical discussions ofobjectivity to the empirical base of science (a topic hithertoneglected in the philosophical tradition but one that, of course themangle [Pickering's view] also addresses). For an argument betweenmyself and Franklin on the same lines as that laid out below, see(Franklin 1990, Chapter 8; Franklin 1991); and (Pickering 1991); andfor commentaries related to that debate, (Ackermann 1991) and (Lynch1991) (p. 197)."For further discussion see (Franklin 1993b)). Although I agree thatmy epistemology of experiment is designed to offer good reasons forbelief in experimental results, I do not agree with Pickering that theyare a set of rules. I regard them as a set of strategies, from whichphysicists choose, in order to argue for the correctness of theirresults. As noted above, I do not think the strategies offered areeither exclusive or exhaustive.There is another point of disagreement between Pickering and myself.He claims to be dealing with the practice of science, and yet heexcludes certain practices from his discussions. One scientificpractice is the application of the epistemological strategies I haveoutlined above to argue for the correctness of an experimental results.In fact, one of the essential features of an experimental paper is thepresentation of such arguments. I note further that writing suchpapers, a performative act, is also a scientific practice and it wouldseem reasonable to examine both the structure and content of thosepapers.5. Hacking's The Social Construction of What?Recently Ian Hacking (1999, chapter 3) has provided an incisive andinteresting discussion of the issues that divide the constructivists(Collins, Pickering, etc.) from the rationalists, like myself. He setsout three sticking points between the two views: 1) contingency, 2)nominalism, and 3) external explanations of stability. Contingency is the idea that science is not predetermined, that itcould have developed in any one of several successful ways. This is theview adopted by constructivists. Hacking illustrates this withPickering's account of high-energy physics during the 1970s duringwhich the quark model came to dominate. (See Pickering 1984a).The constructionist maintains a contingency thesis. In thecase of physics, (a) physics theoretical, experimental, material) couldhave developed in, for example, a nonquarky way, and, by the detailedstandards that would have evolved with this alternative physics, couldhave been as successful as recent physics has been by its detailedstandards. Moreover, (b) there is no sense in which this imaginedphysics would be equivalent to present physics. The physicist deniesthat. (Hacking 1999, pp. 78-79). To sum up Pickering's doctrine: there could have been a researchprogram as successful ("progressive") as that of high-energy physics inthe 1970s, but with different theories, phenomenology, schematicdescriptions of apparatus, and apparatus, and with a different, andprogressive, series of robust fits between these ingredients. Moreoverand this is something badly in need of clarification the "different"physics would not have been equivalent to present physics. Notlogically incompatible with, just different.The constructionist about (the idea) of quarks thus claims that theupshot of this process of accommodation and resistance is not fullypredetermined. Laboratory work requires that we get a robust fitbetween apparatus, beliefs about the apparatus, interpretations andanalyses of data, and theories. Before a robust fit has beenachieved, it is not determined what that fit will be. Not determined byhow the world is, not determined by technology now in existence, notdetermined by the social practices of scientists, not determined byinterests or networks, not determined by genius, not determined byanything (pp. 72-73, emphasis added).Much depends here on what Hacking means by "determined.." If hemeans entailed then I agree with him. I doubt that the world, or moreproperly, what we can learn about it, entails a unique theory. If not,as seems more plausible, he means that the way the world is places norestrictions on that successful science, then I disagree strongly. Iwould certainly wish to argue that the way the world is restricts thekinds of theories that will fit the phenomena, the kinds of apparatuswe can build, and the results we can obtain with such apparatuses. Tothink otherwise seems silly. Consider a homey example, it seems to mehighly unlikely, an understatement, that someone can come up with asuccessful theory in which objects whose density is greater than thatof air fall upwards. This is not, I believe, a caricature of the viewHacking describes. Describing Pickering's view, he states, "Physics didnot need to take a route that involved Maxwell's Equations, the SecondLaw of Thermodynamics, or the present values of the velocity of light(p. 70)." Although I have some sympathy for this view as regardsMaxwell's Equations or the Second Law of Thermodynamics, I do not agreeabout the value of the speed of light. That is determined by the waythe world is. Any successful theory of light must give that value forits speed.At the other extreme are the "inevitablists," among whom Hackingclassifies most scientists. He cites Sheldon Glashow, a Nobel Prizewinner, "Any intelligent alien anywhere would have come upon the samelogical system as we have to explain the structure of protons and thenature of supernovae (Glashow 1992, p. 28)."Another difference between Pickering and myself on contingencyconcerns the question of not whether an alternative is possible, butrather whether there are reasons why that alternative should bepursued. Pickering seems to identify can withought.In the late 1970s there was a disagreement between the results oflow-energy experiments on atomic parity violation (the violation ofleft-right symmetry) performed at the University of Washington and atOxford University and the result of a high-energy experiment on thescattering of polarized electrons from deuterium (the SLAC E122experiment). The atomic-parity violation experiments failed to observethe parity-violating effects predicted by the Weinberg- Salam (W-S)unified theory of electroweak interactions, whereas the SLAC experimentobserved the predicted effect. In my view, these early atomic physicsresults were quite uncertain in themselves and that uncertainty wasincreased by positive results obtained in similar experiments atBerkeley and Novosibirsk. At the time the theory had other evidentialsupport, but was not universally accepted. Pickering and I are inagreement that the W-S theory was accepted on the basis of the SLACE122 result. We differ dramatically in our discussions of theexperiments Our difference on contingency concerns a particulartheoretical alternative that was proposed at the time to explain thediscrepancy between the experimental results.Pickering asked why a theorist might not have attempted to find avariant of electroweak gauge theory that might have reconciled theWashington-Oxford atomic parity results with the positive E122 result.(What such a theorist was supposed to do with the supportive atomicparity results later provided by experiments at Berkeley and atNovosibirsk is never mentioned). "But though it is true that E122analysed their data in a way that displayed the improbability [theprobability of the fit to the hybrid model was 6 x 10-4] ofa particular class of variant gauge theories, the so-called ‘hybridmodels,’ I do not believe that it would have been impossible to deviseyet more variants" (Pickering 1991, p. 462). Pickering notes thatopen-ended recipes for constructing such variants had been written downas early as 1972 (p. 467). I agree that it would have been possible todo so, but one may ask whether or not a scientist might have wished todo so. If the scientist agreed with my view that the SLAC E122experiment provided considerable evidential weight in support of theW-S theory and that a set of conflicting and uncertain results fromatomic parity-violation experiments gave an equivocal answer on thatsupport, what reason would they have had to invent an alternative?This is not to suggest that scientists do not, or should not, engagein speculation, but rather that there was no necessity to do so in thiscase. Theorists often do propose alternatives to existing,well-confirmed theories.Constructivist case studies always seem to result in the support ofexisting, accepted theory (Pickering 1984a; 1984b; 1991; Collins 1985;Collins and Pinch 1993). One criticism implied in such cases is thatalternatives are not considered, that the hypothesis space ofacceptable alternatives is either very small or empty. I don't believethis is correct. Thus, when the experiment of Christenson et al. (1964)detected Ko2 decay into two pions, which seemedto show that CP symmetry (combined particle-antiparticle and spaceinversion symmetry) was violated, no fewer than 10 alternatives wereoffered. These included 1) the cosmological model resulting from thelocal dysymmetry of matter and antimatter, 2) external fields, 3) thedecay of the Ko2 into a Ko1with the subsequent decay of the Ko1 into twopions, which was allowed by the symmetry, 4) the emission of anotherneutral particle, "the paritino," in the Ko2decay, similar to the emission of the neutrino in beta decay, 5) thatone of the pions emitted in the decay was in fact a "spion," a pionwith spin one rather than zero, 6) that the decay was due to anotherneutral particle, the L, produced coherently with the Ko 7)the existence of a "shadow" universe, which interacted with outuniverse only through the weak interactions, and that the decay seenwas the decay of the "shadow Ko2," 8) the failureof the exponential decay law, 9) the failure of the principle ofsuperposition in quantum mechanics, and 10) that the decay pions werenot bosons.As one can see, the limits placed on alternatives were not verystringent. By the end of 1967, all of the alternatives had been testedand found wanting, leaving CP symmetry unprotected. Here the differingjudgments of the scientific community about what was worth proposingand pursuing led to a wide variety of alternatives being tested.Hacking's second sticking point is nominalism, or name-ism. He notesthat in its most extreme form nominalism denies that there is anythingin common or peculiar to objects selected by a name, such as "Douglasfir" other than that they are called Douglas fir. Opponents contendthat good names, or good accounts of nature, tell us something correctabout the world. This is related to the realism-antirealism debateconcerning the status of unobservable entities that has plaguedphilosophers for millennia. For example Bas van Fraassen (1980), anantirealist, holds that we have no grounds for belief in unobservableentities such as the electron and that accepting theories about theelectron means only that we believe that the things the theory saysabout observables is true. A realist claims that electrons really existand that as, for example, Wilfred Sellars remarked, "to have goodreason for holding a theory is ipso facto to have good reasonfor holding that the entities postulated by the theory exist (Sellars1962, p. 97)." In Hacking's view a scientific nominalist is moreradical than an antirealist and is just as skeptical about fir trees asthey are about electrons. A nominalist further believes that thestructures we conceive of are properties of our representations of theworld and not of the world itself. Hacking refers to opponents of thatview as inherent structuralists.Hacking also remarks that this point is related to the question of"scientific facts." Thus, constructivists Latour and Woolgar originallyentitled their book Laboratory Life: The Social Construction ofScientific Facts (1979). Andrew Pickering entitled his history ofthe quark model Constructing Quarks (Pickering 1984a).Physicists argue that this demeans their work. Steven Weinberg, arealist and a physicist, criticized Pickering's title by noting that nomountaineer would ever name a book Constructing Everest. ForWeinberg, quarks and Mount Everest have the same ontological status.They are both facts about the world. Hacking argues thatconstructivists do not, despite appearances, believe that facts do notexist, or that there is no such thing as reality. He cites Latour andWoolgar "that ‘out-there-ness' is a consequence of scientificwork rather than its cause (Latour and Woolgar 1986, p. 180)." I agreewith Hacking when he concludes that,Latour and Woolgar were surely right. We should notexplain why some people believe that p by saying thatp is true, or corresponds to a fact, or the facts. Forexample: someone believes that the universe began with what for brevitywe call a big bang. A host of reasons now supports this belief. Butafter you have listed all the reasons, you should not add, as if itwere an additional reason for believing in the big bang, ‘and it istrue that the universe began with a big bang.’ Or ‘and it is afact.'This observation has nothing peculiarly to do with socialconstruction. It could equally have been advanced by an old-fashionedphilosopher of language. It is a remark about the grammar of the verb‘to explain’ (Hacking 1999, pp. 80-81).I would add, however, that the reasons Hacking cites as supportingthat belief are given to us by valid experimental evidence and not bythe social and personal interests of scientists. I'm not sure thatLatour and Woolgar would agree. My own position is one that one mightreasonably call conjectural realism. I believe that we have goodreasons to believe in facts, and in the entities involved in ourtheories, always remembering, of course, that science is fallible.Hacking's third sticking point is the external explanations ofstability.The constructionist holds that explanations for thestability of scientific belief involve, at least in part, elements thatare external to the content of science. These elements typicallyinclude social factors, interests, networks, or however they bedescribed. Opponents hold that whatever be the context of discovery,the explanation of stability is internal to the science itself (Hacking1999, p. 92). Rationalists think that most science proceeds as it does in thelight of good reasons produced by research. Some bodies of knowledgebecome stable because of the wealth of good theoretical andexperimental reasons that can be adduced for them. Constructiviststhink that the reasons are not decisive for the course of science.Nelson (1994) concludes that this issue will never be decided.Rationalists, at least retrospectively, can always adduce reasons thatsatisfy them. Constructivists, with equal ingenuity, can always find totheir own satisfaction an openness where the upshot of research issettled by something other than reason. Something external. That is oneway of saying we have found an irresoluble "sticking point" (pp.91-92)Thus, there is a rather severe disagreement on the reasons for theacceptance of experimental results. For some, like Staley, Galison andmyself, it is because of epistemological arguments. For others, likePickering, the reasons are utility for future practice and agreementwith existing theoretical commitments. Although the history of scienceshows that the overthrow of a well-accepted theory leads to an enormousamount of theoretical and experimental work, proponents of this viewseem to accept it as unproblematical that it is always agreement withexisting theory that has more future utility. Hacking and Pickeringalso suggest that experimental results are accepted on the basis of themutual adjustment of elements which includes the theory of thephenomenon.Nevertheless, everyone seems to agree that a consensus does arise onexperimental results.II. The Roles of ExperimentA. A Life of Its OwnAlthough experiment often takes its importance from its relation totheory, Hacking pointed out that it often has a life of its own,independent of theory. He notes the pristine observations of CarolynHerschel's discovery of comets, William Herschel's work on "radiantheat," and Davy's observation of the gas emitted by algae and theflaring of a taper in that gas. In none of these cases did theexperimenter have any theory of the phenomenon under investigation. Onemay also note the nineteenth century measurements of atomic spectra andthe work on the masses and properties on elementary particles duringthe 1960s. Both of these sequences were conducted without any guidancefrom theory. In deciding what experimental investigation to pursue, scientistsmay very well be influenced by the equipment available and their ownability to use that equipment (McKinney 1992). Thus, when theMann-O'Neill collaboration was doing high energy physics experiments atthe Princeton-Pennsylvania Accelerator during the late 1960s, thesequence of experiments was (1) measurement of the K+ decayrates, (2) measurement of the K +e3 branchingratio and decay spectrum, (3) measurement of theK+e2 branching ratio, and (4) measurement of theform factor in K+e3 decay. These experiments wereperformed with basically the same experimental apparatus, but withrelatively minor modifications for each particular experiment. By theend of the sequence the experimenters had become quite expert in theuse of the apparatus and knowledgeable about the backgrounds andexperimental problems. This allowed the group to successfully performthe technically more difficult experiments later in the sequence. Wemight refer to this as "instrumental loyalty" and the "recycling ofexpertise" (Franklin 1997b). This meshes nicely with Galison's view ofexperimental traditions. Scientists, both theorists andexperimentalists, tend to pursue experiments and problems in whichtheir training and expertise can be used.Hacking also remarks on the "noteworthy observations" on IcelandSpar by Bartholin, on diffraction by Hooke and Grimaldi, and on thedispersion of light by Newton. "Now of course Bartholin, Grimaldi,Hooke, and Newton were not mindless empiricists without an‘idea’ in their heads. They saw what they saw because theywere curious, inquisitive, reflective people. They were attempting toform theories. But in all these cases it is clear that the observationspreceded any formulation of theory" (Hacking 1983, p. 156). In all ofthese cases we may say that these were observations waiting for, orperhaps even calling for, a theory. The discovery of any unexpectedphenomenon calls for a theoretical explanation.B. Confirmation and RefutationNevertheless several of the important roles of experiment involve itsrelation to theory. Experiment may confirm a theory, refute a theory,or give hints to the mathematical structure of a theory. 1. The Discovery of Parity Nonconservation: A Crucial ExperimentLet us consider first an episode in which the relation between theoryand experiment was clear and straightforward. This was a "crucial"experiment, one that decided unequivocally between two competingtheories, or classes of theory. The episode was that of the discoverythat parity, mirror-reflection symmetry or left-right symmetry, is notconserved in the weak interactions. (For details of this episode seeFranklin (1986, Ch. 1) and Appendix 1). Experiments showed that in the betadecay of nuclei the number of electrons emitted in the same directionas the nuclear spin was different from the number emitted opoosite tothe spin direction. This was a clear demonstartion of parity vilationin the weak interactions. 2. The Discovery of CP Violation: A Persuasive ExperimentAfter the discovery of parity and charge conjugation nonconservation,and following a suggestion by Landau, physicists considered CP(combined parity and particle-antiparticle symmetry), which was stillconserved in the experiments, as the appropriate symmetry. Oneconsequence of this scheme, if CP were conserved, was that theK1o meson could decay into two pions, whereas theK2o meson could not.[10] Thus, observation ofthe decay of K2o into two pions would indicate CPviolation. The decay was observed by a group at Princeton University.Although several alternative explanations were offered, experimentseliminated each of the alternatives leaving only CP violation as anexplanation of the experimental result. (For details of this episodesee Franklin (1986, Ch. 3) and Appendix 2.) 3. The Discovery of Bose-Einstein Condensation: Confirmation After 70 YearsIn both of the episodes discussed previously, those of paritynonconservation and of CP violation, we saw a decision between twocompeting classes of theories. This episode, the discovery ofBose-Einstein condensation (BEC), illustrates the confirmation of aspecific theoretical prediction 70 years after the theoreticalprediction was first made. Bose (1924) and Einstein (1924; 1925)predicted that a gas of noninteracting bosonic atoms will, below acertain temperature, suddenly develop a macroscopic population in thelowest energy quantum state.[11] (For details of this episode see Appendix 3.) C. ComplicationsIn the three episodes discussed in the previous section, the relationbetween experiment and theory was clear. The experiments gaveunequivocal results and there was no ambiguity abnmechanik".Handbuch der Physik 24: 83-272.Petschek, A.G. and R.E. Marshak 1952. "The -Decay of Radium E andthe Pseusoscalar Interaction". Physical Review 85:698-699.Pickering, A. 1981. "The Hunting of the Quark". Isis 72:216-236.–––. 1984a. ConstructingQuarks. Chicago: University of Chicago Press.–––. 1984b. "Against Putting the PhenomenaFirst: The Discovery of the Weak Neutral Current". Studies in theHistory and Philosophy of Science 15: 85-117.–––. 1987. "Against Correspondence: AConstructivist View of Experiment and the Real". PSA1986. A. Fine and P. Machamer (Ed.). Pittsburgh, Philosophy ofScience Association. 2: 196-206.–––. 1989. "Living in the Material World: OnRealism and Experimental Practice." The Uses ofExperiment. D. Gooding, T. Pinch and S. Schaffer(Ed.). Cambridge, Cambridge University Press: 275-297.–––. 1991. "Reason Enough? More on ParityViolation Experiments and Electroweak Guage Theory." PSA 1990,Volume 2. A. Fine, M. Forbes, and L. Wessels. East Lansing, MI:Philosophy of Science Association, 2: 459-469.–––. 1995. The Mangle ofPractice. Chicago: University of Chicago Press.Prentki, J. 1965. CP Violation. Oxford InternationalConference on Elementary Particles, Oxford, England.Pursey, D.L. 1951. "The Interaction in the Theory of Beta Decay".Philosophical Magazine 42: 1193-1208.Raab, F.J. 1987. "Search for an Intermediate-Range Interaction:Results of the Eot-Wash I Experiment". New and Exotic Phenomena:Seventh Moriond Workshop. O. Fackler and J. Tran Thanh Van (Ed.).Les Arcs, France, Editions Frontieres: 567-577.Randall, H.M., R.G.h the Stern-Gerlachresult initially also posed problems for the new theory, after amodification of that new theory, the result confirmed it. In a sense,it was crucial after all. It just took some time.The Stern-Gerlach experiment provides evidence for the existence ofelectron spin. These experimental results were first published in 1922,although the idea of electron spin wasn't proposed by Goudsmit andUhlenbeck until 1925 (1925; 1926). One might say that electron spin wasdiscovered before it was invented. (For details of this episode see Appendix 5).3. Sometimes Refutation Doesn't Work: The Double-Scattering of ElectronsIn the last section we saw some of the difficulty inherent inexperiment-theory comparison. One is sometimes faced with the questionof whether the experimental apparatus satisfies the conditions requiredby theory, or conversely, whether the appropriate theory is beingcompared to the experimental result. A case in point is the history ofexperiments on the double-scattering of electrons by heavy nuclei (Mottscattering) during the 1930s and the relation of these results toDirac's theory of the electron, an episode in which the question ofwhether or not the experiment satisfied the conditions of thetheoretical calculation was central. Initially, experiments disagreedwith Mott's calculation, casting doubt on the underlying Dirac theory.After more than a decade of work, both experimental and theoretical, itwas realized that there was a background effect in the experiments thatmasked the predicted effect. When the background was eliminatedexperiment and theory agreed. (Appendix 6) D. Other Roles1. Evidence for a New Entity: J.J. Thomson and the ElectronExperiment can also provide us with evidence for the existence of theentities involved in our theories. J.J. Thomson's experiments oncathode rays provided grounds for belief in the existence of electrons.(For details of this episode see Appendix 7). 2. The Articulation of Theory: Weak InteractionsExperiment can also help to articulate a theory. Experiments on betadecay during from the 1930s to the 1950s detremined the precisemathematical form of Fermi's theory of beta decay. (For details of thisepisode see Appendix 8.) E. Some Thoughts on Experiment in Biology1. Epistemological Strategies and the Peppered Moth ExperimentOne comment that has been made concerning the philosophy ofexperiment is that all of the examples are taken from physics and aretherefore limited. In this section I will suggest that thesediscussions also apply to biology.Although all of the illustrations of the epistemology of experimentcome from physics, David Rudge (1998; 2001) has shown that they arealso used in biology. His example is Kettlewell's (1955; 1956;1958) evolutionary biology experiments on the Peppered Moth, Bistonbetularia. The typical form of the moth has a palespeckled appearance and there are two darker forms, f.carbonaria, which is nearly black, and f. insularia,which is intermediate in color. The typical form of the mothwas most prevalent in the British Isles and Europe until the middle ofthe nineteenth century. At that time things began to change. Increasingindustrial pollution had both darkened the surfaces of trees and rocksand had also killed the lichen cover of the forests downwind ofpollution sources. Coincident with these changes, naturalists had foundthat rare, darker forms of several moth species, in particular thePeppered Moth, had become common in areas downwind of pollutionsources.Kettlewell attempted to test a selectionist explanation of thisphenomenon. E.B. Ford (1937; 1940) had suggested a two-part explanationof this effect: 1) darker moths had a superior physiology and 2) thespread of the melanic gene was confined to industrial areas because thedarker color made carbonaria more conspicuous to avianpredators in rural areas and less conspicuous in polluted areas.Kettlewell believed that Ford had established the superior viability ofdarker moths and he wanted to test the hypothesis that the darker formof the moth was less conspicuous to predators in industrial areas.Kettlewell's investigations consisted of three parts. In thefirst part he used human observers to investigate whether his proposedscoring method would be accurate in assessing the relativeconspicuousness of different types of moths against differentbackgrounds. The tests showed that moths on “correct”backgrounds, typical on lichen covered backgrounds and darkmoths on soot-blackened backgrounds were almost always judgedinconspicuous, whereas moths on “incorrect” backgroundswere judged conspicuous.The second step involved releasing birds into a cage containing allthree types of moth and both soot-blackened and lichen covered piecesof bark as resting places. After some difficulties (see Rudge 1998 fordetails), Kettlewell found that birds prey on moths in an order ofconspicuousness similar to that gauged by human observers.The third step was to investigate whether birds preferentially preyon conspicuous moths in the wild. Kettlewell used amark-release-recapture experiment in both a polluted environment(Birmingham) and later in an unpolluted wood. He released 630 markedmale moths of all three types in an area near Birmingham, whichcontained predators and natural boundaries. He then recaptured themoths using two different types of trap, each containing virgin femalesof all three types to guard against the possibility of pheromonedifferences.Kettlewell found that carbonaria was twice as likely tosurvive in soot-darkened environments (27.5 percent) as wastypical (12.7 percent). He worried, however, that his resultsmight be an artifact of his experimental procedures. Perhaps the trapsused were more attractive to one type of moth, that one form of mothwas more likely to migrate, or that one type of moth just lived longer.He eliminated the first alternative by showing that the recapture rateswere the same for both types of trap. The use of natural boundaries andtraps placed beyond those boundaries eliminated the second, andprevious experiments had shown no differences in longevity. Furtherexperiments in polluted environments confirmed that carbonariawas twice as likely to survive as typical. An experiment in anunpolluted environment showed that typical was three times aslikely to survive as carbonaria. Kettlewell concluded thatsuch selection was the cause of the prevalence of carbonariain polluted environments.Rudge also demonstrates that the strategies used by Kettlewell arethose described above in the epistemology of experiment. His examplesare given in Table 1. (For more details see Rudge 1998).Epistemological strategiesExamples from Kettlewell1. Experimental checks and calibration in which the apparatusreproduces known phenomena.Use of the scoring experiment to verify that the proposed scoringmethods would be feasible and objective2. Reproducing artifacts that are known in advance to bepresent.Analysis of recapture figures for endemic betulariapopulations.3. Elimination of plausible sources of background and alternativeexplanations of the result.Use of natural barriers to minimize migration.4. Using the results themselves to argue for their validity.Filming the birds preying on the moths.5. Using an independently well-corroborated theory of thephenomenon to explain the results.Use of Ford's theory of the spread of industrial melanism.6. Using an apparatus based on a well- corroborated theory.Use of Fisher, Ford, and Shepard techniques. [Themark-release-capture method had been used in several earlierexperiments]7. Using statistical arguments.Use and analysis of large numbers of moths.8. Blind analysisNot used.9. Intervention, in which the experimenter manipulates the objectunder observationNot present10. Independent confirmation using different experiments.Use of two different types of traps to recapture the moths.Table 1. Examples of epistemological strategies usedby experimentalists in evolutionary biology, from H.B.D.Kettlewell's (1955, 1956, 1958) investigations of industrialmelanism. (See Rudge 1998).2. The Meselson-Stahl Experiment: “The Most Beautiful Experiment in Biology”The roles that experiment plays in physics are also those it playsin biology. In the previous section we have seen thatKetllewell's experiments both test and confirm a theory. Idiscussed earlier a set of crucial experiments that decided between twocompeting classes of theories, those that conserved parity and thosethat did not. In this section I will discuss an experiment that decidedamong three competing mechanisms for the replication of DNA, themolecule now believed to be responsible for heredity. This is anothercrucial experiment. It strongly supported one proposed mechanism andargued against the other two. (For details of this episode see (Holmes2001)).In 1953 Francis Crick and James Watson proposed a three-dimensionalstructure for deoxyribonucleic acid (DNA) (Watson and Crick 1953a).Their proposed structure consisted of two polynucleotide chainshelically wound about a common axis. This was the famous “DoubleHelix”. The chains were bound together by combinations of fournitrogen bases -- adenine, thymine, cytosine, and guanine. Because ofstructural requirements only the base pairs adenine-thymine andcytosine-guanine are allowed. Each chain is thus complementary to theother. If there is an adenine base at a location in one chain there isa thymine base at the same location on the other chain, and vice versa.The same applies to cytosine and guanine. The order of the bases alonga chain is not, however, restricted in any way, and it is the precisesequence of bases that carries the genetic information.The significance of the proposed structure was not lost on Watsonand Crick when they made their suggestion. They remarked, “It hasnot escaped our notice that the specific pairing we have postulatedimmediately suggests a possible copying mechanism for the geneticmaterial.” Figure 21: Possible mechanisms for DNA replication. (Left) Conservativereplication. Each of the two strands of the parent DNA is replicated toyield the unchanged parent DNA and one newly synthesized DNA. Thesecond generation consists of one parent DNA and three new DNAs.(Center) Semiconservative replication. Each first generation DNAmolecule contains one strand of the parent DNA and one newlysynthesized strand. The second generation consists of two hybrid DNAsand two new DNAs. (Right) Dispersive replication. The parent chainsbreak at intervals, and the parental segments combine with new segmentsto form the daughter chains. The darker segments are parental DNA andthe lighter segments are newly synthesized DNA. From Lehninger(1975).If DNA was to play this crucial role in genetics, then there must bea mechanism for the replication of the molecule. Within a short periodof time following the Watson-Crick suggestion, three differentmechanisms for the replication of the DNA molecule were proposed(Delbruck and Stent 1957). These are illustrated in Figure 21. Thefirst, proposed by Gunther Stent and known as conservative replication,suggested that each of the two strands of the parent DNA molecule isreplicated in new material. This yields a first generation whichconsists of the original parent DNA molecule and one newly-synthesizedDNA molecule. The second generation will consist of the parental DNAand three new DNAs.The second proposed mechanism, known as semiconservative replicationis when each strand of the parental DNA acts as a template for a secondnewly-synthesized complementary strand, which then combines with theoriginal strand to form a DNA molecule. This was proposed by Watson andCrick (1953b). The first generation consists of two hybrid molecules,each of which contains one strand of parental DNA and one newlysynthesized strand. The second generation consists of two hybridmolecules and two totally new DNAs. The third mechanism, proposed byMax Delbruck, was dispersive replication, in which the parental DNAchains break at intervals and the parental segments combine with newsegments to form the daughter strands.In this section I will discuss the experiment performed by MatthewMeselson and Franklin Stahl, which has been called “the mostbeautiful experiment in biology”, and which was designed toanswer the question of the correct DNA replication mechanism (Meselsonand Stahl 1958). Meselson and Stahl described their proposedmethod. “We anticipated that a label which imparts to the DNAmolecule an increased density might permit an analysis of thisdistribution by sedimentation techniques. To this end a method wasdeveloped for the detection of small density differences amongmacromolecules. By use of this method, we have observed thedistribution of the heavy nitrogen isotope 15N amongmolecules of DNA following the transfer of a uniformly15N-labeled, exponentially growing bacterial population toa growth medium containing the ordinary nitrogen isotope14N” (Meselson and Stahl 1958, pp. 671-672). Figure 22: Schematic representation of the Meselson-Stahlexperiment. From Watson (1965).The experiment is described schematically in Figure 22. Meselson andStahl placed a sample of DNA in a solution of cesium chloride. As thesample is rotated at high speed the denser material travels furtheraway from the axis of rotation than does the less dense material. Thisresults in a solution of cesium chloride that has increasing density asone goes further away from the axis of rotation. The DNA reachesequilibrium at the position where its density equals that of thesolution. Meselson and Stahl grew E. coli bacteria in a mediumthat contained ammonium chloride (NH4Cl) as the sole sourceof nitrogen. They did this for media that contained either14N, ordinary nitrogen, or 15N, a heavierisotope. By destroying the cell membranes they could obtain samples ofDNA which contained either 14N or 15N. They firstshowed that they could indeed separate the two different mass moleculesof DNA by centrifugation (Figure 23). The separation of the twotypes of DNA is clear in both the photograph obtained by absorbingultraviolet light and in the graph showing the intensity of the signal,obtained with a densitometer. In addition, the separation between thetwo peaks suggested that they would be able to distinguish anintermediate band composed of hybrid DNA from the heavy and lightbands. These early results argued both that the experimental apparatuswas working properly and that all of the results obtained were correct.It is difficult to imagine either an apparatus malfunction or a sourceof experimental background that could reproduce those results. This issimilar, although certainly not identical, to Galileo'sobservation of the moons of Jupiter or to Millikan's measurementof the charge of the electron. In both of those episodes it was theresults themselves that argued for their correctness.  Figure 23: The separation of 14N DNA from 15NDNA by centrifugation. The band on the left is 14N DNA andthat on the right is from 15N DNA. From Meselson and Stahl(1958).Meselson and Stahl then produced a sample of E colibacteria containing only 15N by growing it in a mediumcontaining only ammonium chloride with 15N(15NH4Cl) for fourteen generations. They thenabruptly changed the medium to 14N by adding a tenfoldexcess of 14NH4CL. Samples were taken just beforethe addition of 14N and at intervals afterward for severalgenerations. The cell membranes were broken to release the DNA into thesolution and the samples were centrifuged and ultraviolet absorptionphotographs taken. In addition, the photographs were scanned with arecording densitometer. The results are shown in Figure 24,showing both the photographs and the densitometer traces. The figureshows that one starts only with heavy (fully-labeled) DNA. As timeproceeds one sees more and more half-labeled DNA, until at onegeneration time only half-labeled DNA is present. “Subsequentlyonly half labeled DNA and completely unlabeled DNA are found. When twogeneration times have elapsed after the addition of 14Nhalf-labeled and unlabeled DNA are present in equal amounts” (p.676). (This is exactly what the semiconservative replication mechanismpredicts). By four generations the sample consists almost entirely ofunlabeled DNA. A test of the conclusion that the DNA in theintermediate density band was half labeled was provided by examinationof a sample containing equal amounts of generations 0 and 1.9. If thesemiconservative mechanism is correct then Generation 1.9 should haveapproximately equal amounts of unlabeled and half-labeled DNA, whereasGeneration 0 contains only fully-labeled DNA. As one can see, there arethree clear density bands and Meselson and Stahl found that theintermediate band was centered at (50 ± 2) percent of the differencebetween the 14N and 15N bands, shown in thebottom photograph (Generations 0 and 4.1). This is precisely what onewould expect if that DNA were half labeled. Figure 24: (Left) Utraviolet absorption photographs showing DNAbands from centrifugation of DNA from E. Coli sampled atvarious times after the addition of an excess of 14Nsubstrates to a growing 15N culture. (Right) Densitometertraces of the photographs. The initial sample is all heavy(15N DNA). As time proceeds a second intermediate bandbegins to appear until at one generation all of the sample is ofintermediate mass (Hybrid DNA). At longer times a band of light DNAappears, until at 4.1 generations the sample is almost all lighterDNA. This is exactly what is predicted by the Watson-Cricksemiconservative mechanism. From Meselson and Stahl (1958)Meselson and Stahl stated their results as follows, “Thenitrogen of DNA is divided equally between two subunits which remainintact through many generations…. Following replication,each daughter molecule has received one parental subunit” (p.676).Meselson and Stahl also noted the implications of their workfor deciding among the proposed mechanisms for DNA replication. In asection labeled “The Watson-Crick Model” they noted that,“This [the structure of the DNA molecule] suggested to Watson andCrick a definite and structurally plausible hypothesis for theduplication of the DNA molecule. According to this idea, the two chainsseparate, exposing the hydrogen-bonding sites of the bases. Then, inaccord with base-pairing restrictions, each chain serves as a templatefor the synthesis of its complement. Accordingly, each daughtermolecule contains one of the parental chains paired with a newlysynthesized chain…. The results of the present experiment arein exact accord with the expectations of the Watson-Crick model for DNAreplication” (pp. 677-678).It also showed that the dispersive replication mechanism proposed byDelbruck, which had smaller subunits, was incorrect. “Since theapparent molecular weight of the subunits so obtained is found to beclose to half that of the intact molecule, it may be further concludedthat the subunits of the DNA molecule which are conserved atduplication are single, continuous structures. The scheme for DNAduplication proposed by Delbruck is thereby ruled out” (p. 681).Later work by John Cairns and others showed that the subunits of DNAwere the entire single polynucleotide chains of the Watson-Crick modelof DNA structure.The Meselson-Stahl experiment is a crucial experiment in biology. Itdecided between three proposed mechanisms for the replication of DNA.It supported the Watson-Crick semiconservative mechanism and eliminatedthe conservative and dispersive mechanisms. It played a similar role inbiology to that of the experiments that demonstrated thenonconservation of parity did in physics. Thus, we have seen evidencethat experiment plays similar roles in both biology and physics andalso that the same epistemological strategies are used in bothdisciplines.III. ConclusionIn this essay varying views on the nature of experimental results havebeen presented. Some argue that the acceptance of experimental resultsis based on epistemological arguments, whereas others base acceptanceon future utility, social interests, or agreement with existingcommunity commitments. Everyone agrees , however, that for whateverreasons, a consensus is reached on experimental results. These resultsthen play many important roles in physics and we have examined severalof these roles, although certainly not all of them. We have seenexperiment deciding between two competing theories, calling for a newtheory, confirming a theory, refuting a theory, providing evidence thatdetermined the mathematical form of a theory, and providing evidencefor the existence of an elementary particle involved in an acceptedtheory. We have also seen that experiment has a life of its own,independent of theory. If, as I believe, epistemological proceduresprovide grounds for reasonable belief in experimental results, thenexperiment can legitimately play the roles I have discussed and canprovide the basis for scientific knowledge. BibliographyPrincipal Works:Ackermann, R. 1985. Data, Instruments and Theory.Princeton, N.J.: Princeton University Press.–––. 1991. "Allan Franklin, Right orWrong". PSA 1990, Volume 2. A. Fine, M. Forbes and L. Wessels(Ed.). East Lansing, MI, Philosophy of ScienceAssociation:451-457.Adelberger, E.G. 1989. "High-Sensitivity Hillside Results from theEot-Wash Experiment". Tests of Fundamental Laws in Physics: NinthMoriond Workshop. O. Fackler and J. Tran Thanh Van (Ed.). LesArcs, France, Editions Frontieres:485-499.Anderson, M.H., J.R. Ensher, M.R. Matthews, et al. 1995."Observation of Bose-Einstein Condensation in a Dilute Atomic Vapor".Science 269: 198-201.Bell, J.S. and J. Perring 1964. "2pi Decay of the K2oMeson". Physical Review Letters 13: 348-349.Bennett, W.R. 1989. "Modulated-Source Eotvos Experiment at LittleGoose Lock". Physical Review Letters 62: 365-368.Bizzeti, P.G., A.M. Bizzeti-Sona, T. Fazzini, et al. 1989a. "Searchfor a Composition Dependent Fifth Force: Results of the VallambrosaExperiment". Tran Thanh Van, J. O. Fackler (Ed.). Gif SurYvette, Editions Frontieres.Bizzeti, P.G., A.M. Bizzeti-Sona, T. Fazzini, et al. 1989b. "Searchfor a Composition-dependent Fifth Force". Physical ReviewLetters 62: 2901-2904.Bose, S. 1924. "Plancks Gesetz und Lichtquantenhypothese".Zeitschrift fur Physik 26(1924): 178-181.Burnett, K. 1995. "An Intimate Gathering of Bosons".Science 269: 182-183.Cartwright, N. 1983. How the Laws of Physics Lie. Oxford:Oxford University Press.Chase, C. 1929. "A Test for Polarization in a beam of Electrons byScattering". Physical Review 34: 1069-1074.–––. 1930. "The Scattering of Fast Electrons byMetals. II. Polarization by Double Scattering at RightAngles". Physical Review 36: 1060-1065.Christenson, J.H., J.W. Cronin, V.L. Fitch, et al. 1964. "Evidencefor the 2pi Decay of the Ko2 Meson". PhysicalReview Letters 13: 138-140.Collins, H. 1985. Changing Order: Replication and Induction inScientific Practice. London: Sage Publications.–––. 1994. "A Strong Confirmation of theExperimenters' Regress". Studies in History and Philosophy ofModern Physics 25(3): 493-503.Collins, H. and Pinch, T. 1993. The Golem: What Everyone ShouldKnow About Science. Cambridge: Cambridge University Press.Conan Doyle, A. 1967. "The Sign of Four". The AnnotatedSherlock Holmes. W. S. Barrington-Gould (Ed.). New York: ClarksonN. Potter.Cowsik, R., N. Krishnan, S.N. Tandor, et al. 1988. "Limit on theStrength of Intermediate-Range Forces Coupling to Isospin".Physical Review Letters 61(2179-2181).Cowsik, R., N. Krishnan, S.N. Tandor, et al. 1990. "Strength ofIntermediate-Range Forces Coupling to Isospin". Physical ReviewLetters 64: 336-339.de Groot, S.R. and H.A. Tolhoek 1950. "On the Theory ofBeta-Radioactivity I: The Use of Linear Combinations of Invariants inthe Interaction Hamiltonian". Physica 16: 456-480.Delbruck, M. and G. S. Stent 1957. On the Mechanism of DNAReplication. The Chemical Basis of Heredity. W. D. McElroy andB. Glass. Baltimore: Johns Hopkins Press: 699-736. Dymond, E.G. 1931. "Polarisation of a Beam of Electrons byScattering". Nature 128: 149.–––. 1932. "On the Polarisation of Electrons byScattering". Proceedings of the Royal Society (London) A136:638-651.–––. 1934. "On the Polarization of Electrons byScattering. II.". Proceedings of the Royal Society (London)A145: 657-668.Einstein, A. 1924. "Quantentheorie des einatomigen idealen gases".Sitzungsberischte der Preussische Akademie der Wissenschaften,Berlin: 261-267.–––. 1925. "Quantentheorie des einatomigenidealen gases". Sitzungsberichte der Preussische Akadmie derWissenschaften, Berlin: 3-14.Everett, A.E. 1965. "Evidence on the Existence of Shadow Pions inK+ Decay". Physical Review Letters 14:615-616.Fermi, E. 1934. "Attempt at a Theory of Beta-Rays". Il NuovoCimento 11: 1-21.Feynman, R.P. and M. Gell-Mann 1958. "Theory of the FermiInteraction". Physical Review 109: 193-198.Feynman, R.P., R.B. Leighton and M. Sands 1963. The FeynmanLectures on Physics. Reading, MA: Addison-Wesley PublishingCompany.Fierz, M. 1937. "Zur Fermischen Theorie des -Zerfalls".Zeitschrift fur Physik 104: 553-565.Fischbach, E., S. Aronson, C. Talmadge, et al. 1986. "Reanalysis ofthe Eötvös Experiment". Physical Review Letters 56:3-6.Fitch, V.L. 1981. "The Discovery of Charge-Conjugation ParityAsymmetry". Science 212: 989-993.Fitch, V.L., M.V. Isaila and M.A. Palmer 1988. "Limits on theExistence of a Material-dependent Intermediate-Range Force".Physical Review Letters 60: 1801-1804.Ford, E. B. 1937. "Problems of Heredity in the Lepidoptera."Biological Reviews 12: 461-503.Ford, E. B. 1940. "Genetic Research on the Lepidoptera."Annals of Eugenics 10: 227-252.Ford, K.W. 1968. Basic Physics. Lexington: Xerox.Franklin, A. 1986. The Neglect of Experiment. Cambridge:Cambridge University Press.–––. 1990. Experiment, Right orWrong. Cambridge: Cambridge University Press.–––. 1991. "Do Mutants Have to Be Slain, or DoThey Die of Natutal Causes." PSA 1990, Volume 2. A. Fine,M. Forbes, and L. Wessels. East Lansing, MI: Philosophy of ScienceAssociation, 2: 487-494.–––. 1993a. The Rise and Fall of the FifthForce: Discovery, Pursuit, and Justification in ModernPhysics. New York: American Institute of Physics.–––. 1993b. "Discovery, Pursuit, andJustification." Perspectives on Science 1:252-284.–––. 1994. "How to Avoid the Experimenters'Regress". Studies in the History and Philosophy of Science25: 97-121.–––. 1995a. "The Resolution of DiscordantResults". Perspectives on Science 3: 346-420.–––. 1995b. "Laws and Experiment". Laws ofNature. F. Weinert (Ed.). Berlin, De Gruyter:191-207.–––. 1996. "There Are No Antirealists in theLaboratory". Realism and Anti-Realism in the Philosophy ofScience. R. S. Cohen, R. Hilpinen and Q. Renzong(Ed.). Dordrecht, Kluwer Academic Publishers:131-148.–––. 1997a. "Calibration". Perspectives onScience 5: 31-80.–––. 1997b. "Recycling Expertise andInstrumental Loyalty". Philosophy of Science 64 (4 (Supp.)):S42-S52.–––. 1997c. "Are There Really Electrons?Experiment and Reality". Physics Today 50(10): 26-33.–––. 2002. Selectivity and Discord: TwoProblems of Experiment Pittsburgh: University of PittsburghPress.Franklin, A. and C. Howson 1984. "Why Do Scientists Prefer to VaryTheir Experiments?". Studies in History and Philosophy ofScience 15: 51-62.Franklin, A. and C. Howson 1988. "It Probably is a ValidExperimental Result: A Bayesian Approach to the Epistemology ofExperiment". Studies in the History and Philosophy of Science19: 419-427.Friedman, J.L. and V.L. Telegdi 1957. "Nuclear Emulsion Evidencefor Parity Nonconservation in the Decay Chain pi - mu-e". PhysicalReview 105: 1681-1682.Galison, P. 1987. How Experiments End. Chicago: Universityof Chicago Press.–––. 1997. Image and Logic. Chicago:University of Chicago Press.Gamow, G. and E. Teller 1936. "Selection Rules for the-Disintegration". Physical Review 49: 895-899.Garwin, R.L., L.M. Lederman and M. Weinrich 1957. "Observation ofthe Failure of Conservation of Parity and Charge Conjugation in MesonDecays: The Magnetic Moment of the Free Muon". Physical Review105: 1415-1417.Gerlach, W. and O. Stern 1922a. "Der experimentelle Nachweis derRichtungsquantelung". Zeitschrift fur Physik 9: 349-352.Gerlach, W. and O. Stern 1924. "Uber die Richtungsquantelung imMagnetfeld". Annalen der Physik 74: 673-699.Glashow, S. 1992. "The Death of Science?" The End of Science?Attack and Defense. R.J. Elvee. Lanham, MD.: University Press ofAmericaGooding, D. 1992. "Putting Agency Back Into Experiment".Science as Practice and Culture. A. Pickering (Ed.). Chicago,University of Chicago Press: 65-112.Hacking, I. 1981. "Do We See Through a Microscope". PacificPhilosophical Quarterly 63: 305-322.–––. 1983. Representing andIntervening. Cambridge: Cambridge University Press.–––. 1992. "The Self-Vindication of theLaboratory Sciences". Science as Practice andCulture. A. Pickering (Ed.). Chicago, University of ChicagoPress:29-64.–––. 1999. The Social Construction ofWhat? Cambridge, MA: Harvard University Press.Halpern, O. and J. Schwinger 1935. "On the Polarization ofElectrons by Double Scattering". Physical Review 48:109-110.Hamilton, D.R. 1947. "Electron-Neutrino Angular Correlation inBeta-Decay". Physical Review 71: 456-457.Hellmann, H. 1935. "Bemerkung zur Polarisierung vonElektronenwellen durch Streuung". Zeitschrift fur Physik 96:247-250.Hermannsfeldt, W.B., R.L. Burman, P. Stahelin, et al. 1958."Determination of the Gamow-Teller Beta-Decay Interaction from theDecay of Helium-6". Physical Review Letters 1: 61-63.Holmes, F. L. (2001). Meselson, Stahl, and the Replication ofDNA, A History of "The Most Beautiful Experiment in Biology". NewHaven: Yale University Press.Kettlewell, H. B. D. (1955). "Selection Experiments on IndustrialMelanism in the Lepidoptera." Heredity 9:323-342.Kettlewell, H. B. D. (1956). "Further Selection Experiments onIndustrial Melanism in the Lepidoptera." Heredity10: 287-301.Kettlewell, H. B. D. (1958). "A Survey of the Frequencies ofBiston betularia (L.) (Lep.) and its Melanic Forms in GreatBritain." Heredity 12: 51-72.Kofoed-Hansen, O. 1955. "Neutrino Recoil Experiments". Beta-and Gamma-Ray Spectroscopy. K. Siegbahn (Ed.). New York,Interscience:357-372.Konopinski, E. and G. Uhlenbeck 1935. "On the Fermi Theory ofRadioactivity". Physical Review 48: 7-12.Konopinski, E.J. and L.M. Langer 1953. "The ExperimentalClarification of the Theory of -Decay". Annual Reviews of NuclearScience 2: 261-304.Konopinski, E.J. and G.E. Uhlenbeck 1941. "On the Theory ofBeta-Radioactivity". Physical Review 60: 308-320.Langer, L.M., J.W. Motz and H.C. Price 1950. "Low Energy Beta-RaySpectra: Pm147 S35". Physical Review 77:798-805.Langer, L.M. and H.C. Price 1949. "Shape of the Beta-Spectrum ofthe Forbidden Transition of Yttrium 91". Physical Review 75:1109.Langstroth, G.O. 1932. "Electron Polarisation". Proceedings ofthe Royal Society (London) A136: 558-568.LaRue, G.S., J.D. Phillips, and W.M. Fairbank. "Observation ofFractional Charge of (1/3)e on Matter. Physical ReviewLetters 46: 967-970.Latour, B. and S. Woolgar. 1979. Laboratory Life: The SocialConstruction of Scientific Facts. Beverly Hills: Sage.Latour, B. and S. Woolgar. 1986. Laboratory Life: TheConstruction of Scientific Facts. Princeton: Princeton UniversityPress.Lee, T.D. and C.N. Yang 1956. "Question of Parity Nonconservationin Weak Interactions". Physical Review 104: 254-258.Lehninger, A. L. 1975. Biochemistry. New York: WorthPublishers. Lynch, M. 1991. "Allan Franklin's Transcendental Physics." PSA1990, Volume 2. A. Fine, M. Forbes, and L. Wessels. East Lansing,MI: Philosophy of Science Association, 2: 471-485.MacKenzie, D. 1989. "From Kwajelein to Armageddon? Testing and theSocial Construction of Missile Accuracy". The Uses ofExperiment. D. Gooding, T. Pinch and S. Shaffer (Ed.). Cambridge,Cambridge University Press: 409-435.Mayer, M.G., S.A. Moszkowski and L.W. Nordheim 1951. "Nuclear ShellStructure and Beta Decay. I. Odd A Nuclei". Reviews of ModernPhysics 23: 315-321.McKinney, W. (1992). Plausibility and Experiment: Investigations inthe Context of Pursuit. History and Philosophy of Science. Bloomington,IN, Indiana.Mehra, J. and H. Rechenberg 1982. The Historical Development ofQuantum Theory. New York: Springer-Verlag.Meselson, M. and F. W. Stahl 1958. "The Replication of DNA inEscherichia Coli." Proceedings of the National Academy of Sciences(USA) 44: 671-682. Millikan, R.A. 1911. "The Isolation of an Ion, A PrecisionMeasurement of Its Charge, and the Correction of Stokes's Law".Physical Review 32: 349-397.Morrison, M. 1990. "Theory, Intervention, and Realism".Synthese 82: 1-22.Mott, N.F. 1929. "Scattering of Fast Electrons by Atomic Nuclei".Proceedings of the Royal Society (London) A124: 425-442.–––. 1931. "Polarization of a Beam of Electronsby Scattering". NatureNelson, A. 1994. "How Could Scientific Facts be SociallyConstructed?". Studies in History and Philosophy of Science25(4): 535-547.–––. 1932. "Tha Polarisation of Electrons byDouble Scattering". Proceedings of the Royal Society(London) A135: 429-458.Nelson, P.G., D.M. Graham and R.D. Newman 1990. "Search for anIntermediate-Range Composition-dependent Force Coupling to N-Z".Physical Review D 42: 963-976.Nelson, A. 1994. "How Could Scientific Facts be SociallyConstructed?". Studies in History and Philosophy of Science25(4): 535-547.Newman, R., D. Graham and P. Nelson 1989. "A "Fifth Force" Searchfor Differential Accleration of Lead and Copper toward Lead". Testsof Fundamental Laws in Physics: Ninth Moriond Workshop. O. Facklerand J. Tran Thanh Van (Ed.). Gif sur Yvette, EditionsFrontieres:459-472.Nishijima, K. and M.J. Saffouri 1965. "CP Invariance and the ShadowUniverse". Physical Review Letters 14: 205-207.Pais, A. 1982. Subtle is the Lord… Oxford: OxfordUniversity Press.Pauli, W. 1933. "Die Allgemeinen Prinzipen der Wellenmechanik".Handbuch der Physik 24: 83-272.Petschek, A.G. and R.E. Marshak 1952. "The -Decay of Radium E andthe Pseusoscalar Interaction". Physical Review 85:698-699.Pickering, A. 1981. "The Hunting of the Quark". Isis 72:216-236.–––. 1984a. ConstructingQuarks. Chicago: University of Chicago Press.–––. 1984b. "Against Putting the PhenomenaFirst: The Discovery of the Weak Neutral Current". Studies in theHistory and Philosophy of Science 15: 85-117.–––. 1987. "Against Correspondence: AConstructivist View of Experiment and the Real". PSA1986. A. Fine and P. Machamer (Ed.). Pittsburgh, Philosophy ofScience Association. 2: 196-206.–––. 1989. "Living in the Material World: OnRealism and Experimental Practice." The Uses ofExperiment. D. Gooding, T. Pinch and S. Schaffer(Ed.). Cambridge, Cambridge University Press: 275-297.–––. 1991. "Reason Enough? More on ParityViolation Experiments and Electroweak Guage Theory." PSA 1990,Volume 2. A. Fine, M. Forbes, and L. Wessels. East Lansing, MI:Philosophy of Science Association, 2: 459-469.–––. 1995. The Mangle ofPractice. Chicago: University of Chicago Press.Prentki, J. 1965. CP Violation. Oxford InternationalConference on Elementary Particles, Oxford, England.Pursey, D.L. 1951. "The Interaction in the Theory of Beta Decay".Philosophical Magazine 42: 1193-1208.Raab, F.J. 1987. "Search for an Intermediate-Range Interaction:Results of the Eot-Wash I Experiment". New and Exotic Phenomena:Seventh Moriond Workshop. O. Fackler and J. Tran Thanh Van (Ed.).Les Arcs, France, Editions Frontieres: 567-577.Randall, H.M., R.G. Fowler, N. Fuson, et al. 1949. InfraredDetermination of Organic Structures. New York: Van Nostrand.Richter, H. 1937. "Zweimalige Streuung schneller Elektronen".Annalen der Physik 28: 533-554.Ridley, B.W. (1954). Nuclear Recoil in Beta Decay. Physics.Cambridge, Cambridge University.Rose, M.E. and H.A. Bethe 1939. "On the Absence of Polarization inElectron Scattering". Physical Review 55: 277-289.Rudge, D. W. (1998). "A Bayesian Analysis of Strategies inEvolutionary Biology." Perspectives on Science6: 341-360.Rudge, D. W. (2001). "Kettlewell from an Error Statistician's Pointof View." Perspectives on Science 9:59-77.Rupp, E. 1929. "Versuche zur Frage nach einer Polarisation derElektronenwelle". Zetschrift fur Physik 53: 548-552.–––. 1930a. "Ueber eine unsymmetrischeWinkelverteilung zweifach reflektierter Elektronen". Zeitschriftfur Physik 61: 158-169.–––. 1930b. "Ueber eine unsymmetrischeWinkelverteilung zweifach reflektierterElektronen". Naturwissenschaften 18: 207.–––. 1931. "Direkte Photographie der Ionisierungin Isolierstoffen". Naturwissenschaften 19: 109.–––. 1932a. "Versuche zum Nachweis einerPolarisation der Elektronen". Physickalsche Zeitschrift 33:158-164.–––. 1932b. "Neure Versuche zur Polarisation derElektronen". Physikalische Zeitschrift 33: 937-940.–––. 1932c. "Ueber die Polarisation derElektronen bei zweimaliger 90o - Streuung". Zeitschriftfur Physik 79: 642-654.–––. 1934. "Polarisation der Elektronen anfreien Atomen". Zeitschrift fur Physik 88: 242-246.Rustad, B.M. and S.L. Ruby 1953. "Correlation between Electron andRecoil Nucleus in He6 Decay". Physical Review 89:880-881.Rustad, B.M. and S.L. Ruby 1955. "Gamow-Teller Interaction in theDecay of He6". Physical Review 97: 991-1002.Sargent, B.W. 1932. "Energy Distribution Curves of theDisintegration Electrons". Proceedings of the CambridgePhilosophical Society 24: 538-553.–––. 1933. "The Maximum Energy of the -Rays fromUranium X and other Bodies". Proceddings of the Royal Society(London) A139: 659-673.Sauter, F. 1933. "Ueber den Mottschen Polarisationseffekt bei derStreuun von Elektronen an Atomen". Annalen der Physik 18:61-80.Sellars, W. 1962. Science, Perception, and Reality. NewYork: Humanities Press.Sherr, R. and J. Gerhart 1952. "Gamma Radiation of C10".Physical Review 86: 619.Sherr, R., H.R. Muether and M.G. White 1949. "Radioactivity ofC10 and O14". Physical Review 75:282-292.Smith, A.M. 1951. "Forbidden Beta-Ray Spectra". PhysicalReview 82: 955-956.Staley, K. 1999 "Golden Events and Statistics: What's Wrong withGalison's Image/Logic Distinction." Perspectives on Science 7:196-230.Stern, O. 1921. "Ein Weg zur experimentellen PrufungRichtungsquantelung im Magnet feld". Zeitschrift fur Physik 7:249-253.Stubbs, C.W., E.G. Adelberger, B.R. Heckel, et al. 1989. "Limits onComposition-dependent Interactions using a Laboratory Source: Is Therea "Fifth Force?"". Physical Review Letters 62: 609-612.Stubbs, C.W., E.G. Adelberger, F.J. Raab, et al. 1987. "Search foran Intermediate-Range Interaction". Physical Review Letters58: 1070-1073.Sudarshan, E.C.G. and R.E. Marshak 1958. "Chirality Invariance andthe Universal Fermi Interaction". Physical Review 109:1860-1862.Thieberger, P. 1987a. "Search for a Substance-Dependent Force witha New Differential Accelerometer". Physical Review Letters 58:1066-1069.Thomson, G.P. 1933. "Polarisation of Electrons". Nature132: 1006.–––. 1934. "Experiment on the Polarization ofElectrons". Philosophical Magazine 17: 1058-1071.Thomson, J.J. 1897. "Cathode Rays". Philosophical Magazine44: 293-316.Uhlenbeck, G.E. and S. Goudsmit 1925. "Ersetzung der Hypothese vonunmechanischen Zwang durch eine Forderung bezuglich des innerenVerhaltens jedes einzelnen Elektrons". Naturwissenschaften 13:953-954.Uhlenbeck, G.E. and S. Goudsmit 1926. "Spinning Electrons and theStructure of Spectra". Nature 117: 264-265.van Fraassen, B. 1980. The Scientific Image. Oxford:Clarendon Press.Watson, J. D. 1965. Molecular Biology of the Gene. NewYork: W.A. Benjamin, Inc. Watson, J. D. and F. H. C. Crick (1953a). "A Structure forDeoxyribose Nucleic Acid." Nature 171: 737. Watson, J. D. and F. H. C. Crick (1953b). "Genetical Implicationsof the Structure of Deoxyribonucleic Acid." Nature 171:964-967. Weinert, F. 1995. "Wrong Theory--Right Experiment: The Significanceof the Stren-Gerlach Experiments". Studies in History andPhilosophy of Modern Physics 26B(1): 75-86.Winter, J. 1936. "Sur la polarisation des ondes de Dirac".Academie des Science, Paris, Comptes rendus hebdomadaires desseances 202: 1265-1266.Wu, C.S. 1955. "The Interaction in Beta-Decay". Beta- andGamma-Ray Spectroscopy. K. Siegbahn (Ed.). New York, Interscience:314-356.Wu, C.S., E. Ambler, R.W. Hayward, et al. 1957. "Experimental Testof Parity Nonconservation in Beta Decay". Physical Review 105:1413-1415.Wu, C.S. and A. Schwarzschild (1958). A Critical Examination of theHe6 Recoil Experiment of Rustad and Ruby. New York, ColumbiaUniversity.Other Suggested ReadingAckermann, R. 1988. "Experiments as the Motor of ScientificProgress". Social Epistemology 2: 327-335.Batens, D. and J.P. Van Bendegem, Eds. 1988. Theory andExperiment. Dordrecht: D. Reidel Publishing Company.Bogen, J. and J. Woodward 1988. "Saving the Phenomena". ThePhilosophical Review 97: 303-352.Burian, R. M. (1992). "How the Choice of Experimental OrganismMatters: Biological Practices and Discipline Boundaries."Synthese 92: 151-166.Burian, R. M. (1993). "How the Choice of Experimental OrganismMatters: Epistemological Reflections on an Aspect of BiologicalPractice." Journal of the History of Biology26: 351-367.Burian, R. M. (1993b). "Technique, Task Definition, and theTransition from Genetics to Molecular Genetics: Aspects of the Work onProtein Synthesis in the Laboratories of J. Monod and P. Zamecnik."Journal of the History of Biology 26:387-407.Burian, R. M. (1995). Comments on Rheinberger. Concepots,Theories, and Rationality in the Biological Sciences. G. Wolters,J. G. Lennox and P. McLasughlin. Pittsburgh: University of PittsburghPress: 123-136.Gooding, D. 1990. Experiment and the Making of Meaning.Dordrecht: Kluwer Academic Publishers.Gooding, D., T. Pinch and S. Schaffer, Eds. 1989. The Uses ofExperiment. Cambridge: Cambridge University Press.Koertge, N., Ed. 1998. A House Built on Sand: ExposingPostmodernist Myths About Science. Oxford: Oxford UniversityPress.Nelson, A. 1994. "How Could Scientific Facts be SociallyConstructed?". Studies in History and Philosophy of Science25(4): 535-547.Pickering, A., Ed. 1992. Science as Practice and Culture.Chicago: University of Chicago Press.Pickering, A. 1995. The Mangle of Practice. Chicago:University of Chicago Press.Pinch, T. 1986. Confronting Nature. Dordrecht:Reidel.Rasmussen, N. 1993. "Facts, Artifacts, and Mesosomes: PracticingEpistemology with the Electron Microscope". Studies in History andPhilosophy of Science 24: 227-265.Rheinberger, H.-J. (1997). Toward a History of EpistemicThings. Stanford: Stanford University Press.Shapere, D. 1982. "The Concept of Observation in Science andPhilosophy". Philosophy of Science 49: 482-525.Weber, M. (2005). Philosophy of Experimental Biology.Cambridge: Cambridge University Press.Other Internet Resources[Please contact the author with suggestions.] Related Entries confirmation | logic: inductive | rationalism vs. empiricism | scientific method | scientific realismAcknowledgmentsI am grateful to Professor Carl Craver for both his comments on themanuscript and for his suggestions for further reading. Copyright © 2007 byAllan Franklin<allan.franklin@colorado.edu> |
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