ackermann-1989-the-new-experimentalism.pdf

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Brit. ]. Ph il. Sci. 40 (1989) , 185-190 Printed in Great Britain

REVIEW ARTICLEThe New Experimentalism*

Allan Frank lin has written an im porta nt book tha t should be required readingfor philosophers of science. Franklin, an experimental high-energy physicistwho is now concentrating on the history and philosophy of science, offersprecisely what might be expected from an experimental physicist; a layout ofdata concerning experimental sequences in physics. Four important experi-mental sequences are considered in detail; the discovery of parity nonconser-vation , th e discovery of the failure of CP inva rian ce , M illikan's discovery of th eunit charge of the electron, and the nondiscovery of parity nonconservation.The last of these, marked by the failure to observe something important, isespecially interesting, since it avoids projecting experimental sequences worthrecovering as only those that cu lm inate in success. The data ga thered from theexperimental sequences is deployed to question existing pronouncements byphilosophers of science on experiment, but Franklin does not develop anarticulated general philosophy of science that incorporates his new experi-m entalism. This book is a provocation for any cur ren t p hilosopher of sciencew ho w ould develop an acco unt of science, th at could tak e the details of actua lexperimental practice into account.

If philosophers will have to draw some of their own conclusions fromFranklin's study, the significance of his focus on experimentation is worthsome discussion. The philosophy of science tha t developed ou t of 20 th cen turypositivism placed a heavy foundational emphasis on observational fact as themeans of controlling theoretical growth, but although theoretical statementswere logically articulated against observational statements in increasinglysophisticated ways as positivism developed, positivism paid little attention tothe way in which statements of observational fact were produced inexperimental practice. One simply began to philosophize on the assumptionthat science was capable of delivering a data base of settled observationalstatem ents. In the vengeful dism antling of positivism un der take n after K uh n'swork, the old connotations of fact were replaced by assertions tha t theoreticalexpectations somehow determined the observations of science, and later bysuggestions th at ob servations are con structed by groups of scientists enga gedin a social process of negotiatio n. N either of these positions is really com patiblewith the intuition that experimental observation and theoretical conjecture* Review of Allan Franklin [1 98 6] : The Neglect of Experiment. Cambridge: Cambridge UniversityPress, xii + 29 0 pp. ISBN 0-52 1-32 016 -X .

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186 Robert Ackermannshould, somehow, have a symmetrical status with respect to scientificdevelopment, e ither being capable of producing a tem porary fixed point o ntowh ich progress can be hinged. In order to recover this funda m ental intuitionbased on scientific practice, a number of recent studies have gone back to thehistory of science to stud y experimentation as a m eans of grounding the na tureand origins of the observational facts that many still think must offerimportant objective constraints for scientific theory, at least at certain pivotalpoints in scientific development. Empiricism is in this way resurrected(although transformed) by finding a philosophical account of experimentaldata th at a re especially wo rth hav ing, and tha t function as solid hinge pointsfor controlling theoretical conjectures. Experiment must be important toscience, or it would die out as an outmoded fashion. Some philosophicalaccount of its ongoing importance seems required.

A philosophical context for Frank lin's work is provided by Hack ing [1 98 3] .Hack ing suggests th at the old m odel of the stru cture of science, in w hich layersof theory and observation a re brou gh t into a logical linkage by such notion s asexplanation and confirmation, needs to be replaced by a set of activities inscience including speculation, calcu lation, an d ex perim entation. T hese activi-ties are to be related by the production of (usually simplified) models in acon text th at allows clear poin ts of con tact, th e models being developed w ith aneye to easy com putation and accessible experim ental verifications. H acking'ssurvey of the complexity of actual scientific practice makes a powerful case forthe replacement th at h e proposes. An imp ortant point of comparison betweenthe old notion of observation an d the newe r conc entration on expe rimen tationis tha t an experim ent is a com plex activity und ertak en over time (involving thedesign and m anu facture of equipm ent, the calibration of equipm ent, checks onthe proper functioning of the eq uipm ent, etc.) that m ay issue in o bservationsthat can be reported as data. What's needed in this context is a discussion ofwhether specific experimental practices can in some sense legitimate orvalidate observational reports, and how the strength of such legitimationm ight be taken into acc oun t in a philosophy of science. Ha cking's suggestionpoints to a legitimate a rea of exp loration, b ut at this point no settled d irectionsof development for the new experimentalism have come into view.

If the notion of experimentation is to be central to a new philosophy ofscience, there are at least two possibilities to consider: that the notion ofexperimental legitimation could be exploited towards the end of providing anew experimental foundationalism, and that the notion of experimentallegitimation could be exploited towards the end of providing a dialecticalaccount of scientific progress in which either theory or experiment couldprovide the temporary support and constraint for the tentative advance of theother, given the concrete set of scientific practices available at a specific pointin time. Franklin tend s tow ards the first of these op tions, asking as his cen tralphilosophical questions what role experiment plays in theory selection or

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The New Experimentalism 187confirmation, and how experiments can be organized so as to result in therational separation of experimental fact from experimental artifact. But nomatter how persuasively rational a retrospective account of physics experi-ments may be, such an account cannot settle the question of whether amethodology involving experimentation can be made applicable to contem-porary grow th points in physical theory. Such a methodology w ould require aframing philosophy that Franklin does not provide in philosophically satisfy-ing detail. At times, Franklin wa vers subtly b etween suggesting th at th ere is anepistemology that can distinguish experimental fact from artifact, andsuggesting the somewhat more sceptical conclusion that observational factscan be accepted as valid w he n all of the plausible sources of erro r in th e relev antexperimental sequences have been eliminated. The gap between these twopositions could only be closed by a philosophical account of plausibility. Intending to think of fraud, or outrig ht m istake, rath er t ha n of error, as the majorfoil to validated experimental work, Franklin slips past some of the difficultieswith the notion of plausibility that seems so crucial to his methodologicalrem ark s. T ha t Franklin ha sn 't yet closed the gap is evident in his discussion ofMillikan's oil drop experiment, where his account of Millikan's apparentlyprescient and simultaneously seemingly arbitrary exclusion of specific dataraises once again the ro ugh details of practice tha t always seem to cut againstthe idea that a generally satisfactory epistemology can be teased out of theexperim ental narratives . It is the roug h data, contrasted with the philosophicaltemptations, that provides the philosophical excitement in Franklin's discus-sion.

It would seem reasonable to ask whether the narratives offered, no matterhow stimulating in their detail, can be regarded as the indubitable core of theexperime ntal sequences in question. The reaction to H anson [19 63 ] suggestedthat different laboratories involved in the same major experimental sequencesca n be inserted at th e nod es of a kind of parody of popular a cc ou nts of relativitytheory in which each laboratory sees itself as the centre of progress, its ownactivities causing the reactions and developments in the other laboratories.Probably there would be specialist quibbles with these narratives, anddubieties expressed by some of the participants, but these narratives suggestthat a crucial level of scientific historiography is now being attained byscientists wh o becom e reflective historian s of their craft. Th is kind of in tern alhistory is likely to be decisive in the next stages of piecing together moreadequate philosophies of science. Franklin's narratives are basically exposi-tory, but the level of exposition depends on some prior knowledge of thephysics involved. Many philosophers will have to put Franklin's book downand consult other material if they are to get beyond the gist of the reasons forthe experimen tal sequenc es. Between the literature suggested in the footnotesand the bibliography, however, it is possible to come onto a quite detailedun ders tand ing of these experimental sequences and their complexities from a

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188 Robert Ackermannrath er m odest basis. W orking at Franklin's text is likely to put some useful fleshonto the bare bones of a philosopher's conception of the reporting ofobservational data. This is history at a level that should be the input into thephilosophy of science as its experimental check.

An important subtext of Franklin's histories concerns the question of whyexperiment has been rigorously neglected in history and philosophy of scienceby comparison to theory. Almost all physicists were experimentalists (if alsotheorists) until the 20th century, giving physics a grounding in an intimateknowledge of experimentation that would be difficult to locate in mostphilosophical accounts of theorizing in physics. The emerging age ofauton om ous theorists was cau ght up into emerging posit ivism in a way tha tseems in retrospect to have caused experimentalists to recede automaticallyinto the background, partly because positivism looked at the logical structureof written scientific books and papers, and writing is both essential to historyand yet biased towards the representation of theory. An irony of Franklin'sbook is that an actual experimental set-up is only portrayed once in its fullycontingent form, and that in the glorious confusion of apparatus in the dustjacket photo grap h. Inside, as an all 'histories' of expe rime ntation, experimen -tal set-ups are given in schematic diagrams that portray the theory of howapparatus could work so as to produce meaningful data, and observationaldata are represented in the smoothed form gathered from properly workingapparatus (with the notable exception of reproductions of some of Millikan'sdata sheets, and some reproductions of electron micrographs). In fact, thedetails of experim ental sequences represent a n alm ost irrational oppo rtunismto the orderly philosophical mind. An experim entalist may wish to measu re acertain phen om enon , but have available an app aratus tha t can only me asureano ther p heno m enon , so tha t progress involves turn ing the first phen om enoninto the second so that it can be measured. It may be that one piece ofapparatus designed to produce the phenomenon to be measured can only beplaced where one would like to place the only apparatus that can apparentlym easu re the phe no m eno n. In a dizzying variety of such variations, exp erimen-talists mus t perm ute and adjust w ha t is available in order to simulate w ha t isdesired. The validity of expe rime ntal results for scientists often depe nds on anintimate scientific grasp of what's available in the way of equipment,thre aten ing an y logical na rrative tha t doe sn't fill in this surro und with failingto produce the data required for an understanding of scientific judgments ofvalidity. The co nstraints on experim ental sequence s are bu t one of the thingsth at m ust be m ore reflectively explored before the inh ere nt prob lems in w ritingexperimental histories can be resolved in a manner that would allow a fullerprobing of the possibilities latent in the new experimentalism for thephilosophy of science.Galison [1987] provides an associated and complementary look at experi-m ental sequences in physics. Galison asks explicitly wh y experimen ts end, th at

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The New Experimentalism 189is, why experimenters stop performing a given experiment, and move on tonew ones. A refinement in Galison's accou nt relevan t to evaluating F ranklin isthat Galison finds the appropriate ending of experiments in his experimentalsequences to depend on the kind of measuring and data analysis devices thatare involved in the sequences. Also dealing with some modern high-energyexperiments, Galison exploits a distinction between an image-producingapparatus and a counting apparatus. An experiment involving an image-produ cing ap par atus often ends approp riately w ith a 'golden event, ' th at is, apicture or image of something whose existence has been conjectured, butpossibly questioned. An exp eriment involving a counting app aratu s often endsappropriately when a decision based on some probability model suggests thatenough counts have been taken for some purpose. A counting sequence willtypically not have quite as decisive a final (ending) event. Galison is not asconcerned with the question of legitimation as Franklin seems to be, notingthat experiments never have a strictly logical terminus, so that the decision toend expe rimen t alw ays involves risk. Not surprisingly, G alison is m ore relaxedabout Millikan's missing drops, observing that Millikan's pragmatism andexperienced eye caused him to make decisions that we can recognize inretrospect as justified. Galison thus moves more towards the philosophicalequipoise of theory and experiment suggested above, and a joint reading ofGalison and Franklin is highly recommended as a way of becoming aware ofthe space opened up for consideration by w ha t seem to be two m ajor varian tsin the emerging new experimentalism.

It has already been noted that Franklin attacks some extant philosophicalopinion on t he b asis of his narr ative s. At times, some very sha rp points aga instphilosophical opinion are scored. For example, philosophers w ho suppose tha tincreasing refinement of experim ental techniqu e and ins trum enta tion willcause a grad ual (or asymtotic) approxim ation of the true data values should beshocked by Fra nklin 's decisive cou ntere xam ples in w hich su dden large leaps tonew values can be observed in experimental sequences that seemed to havebeen converging to 'correct' values. At times, there is an apparent fixation onthe past of the philosophy of science. Franklin worries too much about theQuine-Duhem problem, which he would like to outflank by an elaborateBayesian solution involving an experimentalist setting of the prior probabili-ties of auxiliary hypotheses. The Quine-Duhem problem is generated withinthe old philosophy of science by its reliance on the logical articulation of theoryand o bservation. A m ore thoro ug h rew orking of philosophical co ncernswithin th e new philosophy of replacem ents suggested by Hacking would m akethe Quine-D uhem problem s, as it is traditiona lly formu lated, simply irrelev ant.The m odels used to connect theory and d ata, or more properly theoretical andexperimental activity, are not in general logical consequences of acceptedstatements of theory or data, but simplifications of complexity chosen by anadroit manipulation of simplifications against the background of the acceptedmathematical practices.

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19 0 Robert Ackerma nnThe philosophy of science seems to be in a state of flux, and th e possibilitiesopened up by the new experimentalists seem to offer genuine hope for a

recovery of some of the solid intuitions of the past about the objectivity ofscience, but in the con text of a m uch m ore detailed and articulate un derstand -ing of actual scientific practice. If the studies of experimental sequences nowbeing offered seem driven by the old paradigm of physics as central, thesestudies provide plenty of material for intelligent cross-fertilization and newtheorizing as more data on experimentation in other sciences becomesavailable. Fran klin's book should con tinu e to be central in new developm ents.ROBERT ACKERMANN

The University of Massachusetts at AmherstREFERENCESGALISON, P. [1987] How Experiments End. Chicago: The University of Chicago Press.HACKING, I . [1983]: Representing and Intervening. Cambridge: Cambridge University

Press.HANSON, N. [1963 ]: The Concept of the P ositron. Cam bridge: Cambridge University Press.

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