O R G A N O N 3(1966) MÉTHODOLOGIE GÉNÉRALE
K aïkhosrow D. Irani (U nited States)
CONDITIONS OF JUSTIFICATION IN THE HISTORY OF SCIENTIFIC DISCOVERY
It is extrem ely difficult to form ulate a precise and complete defini tion of science. This is because it consists of a v arie ty of activities, it asks different types of questions and establishes d ifferen t kinds of propo sitions. However, we w ill find agreem ent in th e judgm ent th a t in scien ce we attem p t to discover th e explanations of phenom ena. In achieving this we construct universal propositions or law -like statem ents and establish them by em pirical cofirm ation. We also dem and th a t th e law - -like propositions give form ulations of th e causes of events, or if th ey are functional relations betw een variables, the change in the value of one variable resu lt in a change in th e other. This is not to assert th a t th ere are no exceptions to these form ulations, in any case, not only are these th e m ost usual form s of laws b u t also these are th e ideal form s of laws tow ards which scientific inquiry steadily aims. These law s th en function as prem ises from w hich the phenom enon to be explained m ay be deduced. The establishm ent of these laws is considered in the stan dard trea tm e n t of traditional inductive logic or th e m ore refined m ethods of th e recently explicated hypothetico-deductive m ethod.
The laws a re them selves explained by th e construction of theories. A theory is a set of propositions, w hich we m ay call postulates, from which th e law;s to be explained m ay be deduced. The distinction betw een laws and theories is th a t th e term s in a law m ust be operationally de fined, w hereas th e term s in the postulates of a th eo ry are not so de fined. W hat th e theoretical term s such as “m olecule”, “atom ”, “p ro to n ”, “light w ave”, “force field”, etc. designate are unobservables. The esta blishm ent of theories is sim ilar to th a t of laws; we deduce new obser vable consequences from the theories and v erify them . However, th ere is an additional step here which m ust be noticed. To deduce observable consequences from postulates containing term s w hich refer to unobser vables we m ust relate com binations of unobservable term s to obser
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vable term s. These sem antic relations betw een two types of term s are sometimes called coordinating definitions or correspondence rules. Thus th e deduced consequences of the theo ry are “tra n sla te d ” into the lan guage of observation term s (which include operationally defined term s) and then verified. This ty p e of establishm ent is called indirect v erifi cation. W hen a consequence of a th eo ry is em pirically falsified we sub ject the th eo ry to some alteration u n til the conflict betw een the p re diction and th e observation is elim inated. The theory explains all the propositions, i.e., laws or law -like statem ents th a t are deduced from it.
The significant criterion of justification for both laws and theories is the one of em pirical verification of predictions. This criterion, as ord in arily understood, would force us to reject a law or theory w hen its predictions are em pirically contradicted. The question th at arises now is w hat precisely do we do w hen such a contradiction arises. We can always, or alm ost always, postulate the occurrence of some laten t phenom enon, or the presence of a hidden entity or power which rem o ves the contradiction, i.e., which m akes the contradiction a m erely ap p aren t one. Such instances are w ell know n to th e historian of science in the theo ry of p lan etary motion in astronom y, in early physiology, in th e phlogiston theory, etc. W hat such a methodological procedure does is to m ake the theory quite unfalsifiable. To perm it such a pro cedure would be, according to most methodologists of science, to fail to m ake the crucial distinction betw een science, on the one hand, and w hat is pejoratively called m etaphysics on th e other. Hence we add another criterion to th e effect th a t if an existential proposition is added to a theory or law to “save” it from having its prediction contradicted, th a t existential proposition m ust of itself be independently em pirically confirmed.
B ut consider now the postulation of th e neutrino. The spectra of electrons in the beta-decay of radioactive nuclei contradicted th e con servation requirem ents of quantum mechanical theory under w hich it was subsum ed. The neutrino, a particle, was postulated w ith the appro p riate properties and w as assumed to leave th e nucleus w ith th e rig h t velocity so th a t energy and m om enta w ere conserved and the other requirem ents of qu antum m echanics k ep t inviolate. The existence of the neutrino was em pirically established two decades after its postulation, b u t its existence was assumed and utilized quite extensively before the em pirical establishm ent was achieved. W hat methodological reason can we give for this acceptance which was obviously in violation of an em pirical criterion of justification in science? We could have said th a t th e process of beta-decay does not obey conservation principles, bu t it was felt th a t th is w ould be, somehow, intolerable.
To investigate this situation let us first develop the notion of a c o n c e p t u a l f r a m e w o r k . Most theories, b u t certainly, all
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theories w ith ontological postulates, have conceptual fram ew orks im bedded in them . By a th eo ry w ith ontological postulates w e m ean a theory w hich asserts as one of its postulates th a t such and such a thing exists; for example, th e postulates th a t m olecules exist, atoms exist, mass points exist, etc. In such a theory, the phenom ena it ex plains are alw ays in terp reted b y some correspondence ru les to be chan ges in the m anifestations of the properties of these fu n dam ental e n ti ties.
If a theo ry is v ery com prehensive and has extensive confirm ation th e conceptual fram ew ork of the th eo ry comes to1, be considered as a tru e description of reality.
The conceptual fram ew ork of a theory is a q u alitativ e statem en t of w h at we consider to be th e fundam ental existing elem ents and the w ays th eir properties or relatio n change in time. Thus th e conceptual fram ew ork usually consists of an ontological proposition and a d y n a m ical proposition. There m ay also be some other propositions about the relations betw een the two. But the specific relations of th e m agnitudes of types of variations, i.e. th e equations rela tin g th e entities and th e ir properties, are stric tly p art of the theory and not th e conceptual f r a m ework. Thus, for example, th e conceptual fram ew ork of classical che m istry is th a t all substances in n atu re are elem ents or com binations of elem ents. T here w ere 92 such elements. F u rtherm ore, each elem ent consists of atom s identical in w eight and chem ical properties. The atom s have fixed values and fixed affinities for other specified atoms. According to this conceptual fram ew ork ev ery substance in n a tu re is com prehended in term s of its structure, i.e., th e ingredient elem ents combined in various arch itectu ral form s in accordance w ith th eir re s pective valences and affinities; and all change of substances is com prehended as breakdow n of the arch itectural forms, i.e., th e molecules, into their ingredients or the reassem bling of some of the atom s into other molecules. W hat m ust be noticed here is th a t th e conceptual fram ew ork does not itself constitute a theory, for, by itself, it predicts or explains nothing b u t form ulates the general q u alitativ e principles in term s of w hich the stru c tu re and function or transform ation of all substances is to be interpreted. W hen theories of specific phenom ena such as acid base neutralization, or stru ctu re and activity of arom atic organic com pounds or electrolysis, etc., w ere constructed specific postulates con cerning the properties, valencies, affinities of individual elem ents w ere form ed and operational tests for identifying th e concepts or com bination of concepts w ere constructed. The theory th u s explains and predicts phenom ena. In th e course of its developm ent as the th eo ry is altered, corrected or extended the postulates change b u t th ey are all u n der th e same conceptual fram ew ork. The conceptual fram ew ork provides th e concepts and types of properties and relations from w hich th e appro-5 — O r g a n o n , N r 3/66
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p riate postulates of th e theory are constructed. Thus d ifferen t and even conflicting theories m ay be un der th e same conceptual fram ew ork.
P erhap s the most pervasive conceptual fram ew ork in th e history of m odern science is th e one of N ew tonian Mechanics. This m ay be some w hat incom pletely form ulated as follows:
1) All objects are collections of points having mass and location in an independent space and tim e system of coordinates.
2) All change in motion is th e effect of forces acting on mass points and having the properties of vectors.
3) Several forces acting on a body can be added according to vecto rial rules.
A ny theory form ulated w ithin this fram ew ork w ould be required to provide techniques for m easuring space and tim e and for specifying the values of various forces of w hich there m ay be m any varieties. The theory m ust have also postulates relatin g th e m agnitude of the force to th e m agnitude of th e resu ltan t motion. Thus differen t specific theories m ay have different specific techniques and relations b u t still rem ain w ith in th e general type of relations which characterize th e conceptual fram e of N ew tonian Mechanics. The conceptual fram e w ill be seen to contain an ontological postulate (1), a dynam ical postulate (2) w hich is a causal statem en t explaining change, and th e other statem ent (3) is a w ay of dealing w ith m ultiplicity of causes.
L et us see how this conceptual fram ew ork functions. Suppose a phy sicist (Newtonian physicist) w ere exam ining a problem of motion. He would im m ediately consider th e moving body as a collection of mass points. Upon these points he w ould assume some force to be acting such th a t change in motion was proportional to th a t force. Then he would use recognized techniques for identifying and calculating these forces. Suppose he was unsuccessful in discovering these forces, would he be inclined to reject th e fram ew ork of mechanics? Of course not. He would say th a t som ew here or other th ere is a force to be discovered. The application of the conceptual fram ew ork has become for him the very condition of intelligibility of an explanation of motion. F ittin g th e phe nomena of motion into this fram ew ork is w h at he m eans by explaining motion. The conceptual fram ew ork functions as a set of in terrelated con cepts into which th e phenom ena are tran slated and th en th e appropriate search for causes takes place in this translated schema.
We see now w hat happens in the history of a successful scientific theory. The th eo ry is established as more and m ore verifiable conse quences are deduced from it. The theory is treated as a highly confir med set of descriptive statem ents. B ut then w hen some phenomenon falling w ithin its scope is not obviously deducible from it we insist upon th e phenom enon being in terp reted in term s of th e th eo ry and produce other propositions for this in terp reta tio n to succeed. This is how the
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neutrin o w as postulated. A t this stage th e th eo ry is functioning norm a- tively and not ju st descriptively. The reason for its norm ative function is th a t th e conceptual fram ew ork itself has acquired th e statu s of a ju sti fying principle. I t is this norm ative operation w hich justifies th e postu lation of entities and properties of th e ty p e falling w ith in its conceptual fram ew ork, even though th e ir existence is not justified by em pirical criteria. Of course, if th e conceptual fram ew ork forces us to in v en t m ore and m ore entities for w hich no em pirical evidence is found in fu tu re research the disu tility of th e th e o ry increases and in th e course of tim e a new theory emerges, and if such theories are rep eatedly discon- firm ed em pirically th e en tire conceptual fram ew ork is replaced by another.
The reason w hy conceptual fram ew orks of successful theories h ave th is norm ative pow er is th a t th ey incorporate descriptively conditions w hich satisfy some highly general criteria of scientific knowledge. This notion of th e methodology of science can be explicated by construing its task to be the form ulation of a set of m eta-scientific principles to w hich w e would re fe r in deciding on the acceptance or rejection of a propo sition or th eo ry into th e body of scientific knowledge. If we believe th e m ethodology of science to be w hat em piricism takes it to be th e n w e have only tw o methodological principles: (i) th a t every proposition in th e body of scientific know ledge m ust be em pirically confirm ed and (ii) th a t th e set of all such propositions m ust not be inconsistent. B ut th e functioning of conceptual fram ew orks indicates th a t th e m ethodology of science is m ore complicated. It m anifests the efforts of scientists to in te rp ret and fit the data of observation into conceptual fram ew orks w hich im plies th a t some other principles are a t w ork.
It is generally agreed th a t we have a criterion of explanation in scien ce. By this one m eans th a t a proposition cannot be perm itted to rem ain in th e body of scientific know ledge unless it explains other propositions or is itself explained. In other words, all the propositions of th e body of scientific knowledge are bound into the deductive scheme of explanation; th ey appear as prem ises and explain or as conclusions and are explained. A proposition totally detached from th e body of scientific know ledge constitutes a problem for scientific inquiry. It is also agreed th a t pro positions accepted into th e body of know ledge m u st be em pirically confirmed, i.e. m ust have inductive support and th u s lead to successful prediction. This is th e em pirical criterion. B ut th e re are other criteria. We shall m ention only two: (i) the criterion of objectivity, i.e., th e in dependent existence and description of en tities and events in n atu re, and (ii) th e criterion of causality in term s of w hich all change is com prehended. These two criteria, even if rendered precise, rem ain quite abstract hence difficult to apply. The conceptual fram ew orks m entioned above are schemes w hich in th e ir description incorporate these criteria
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and thus become conceptually effective m eans of interp retin g pheno m ena in accordance w ith these criteria. This is th e basis of their norm a tive power. It would be w rong to th in k th a t conceptual fram ew orks are adhered to m erely out of intellectual habituation or conditions or inertia, or th a t they are conventional accidents in the h isto ry of ideas. In part, th ey reflect the im aginative constructs of the scientific mind which m ay change from tim e to tim e b u t th e ir function in the methodology of science rests on th e incorporation of the epistemological criteria of science itself.
The h isto ry of science is not m erely an account of the observations of nature, the discoveries of phenom ena and th e prom ulgations of laws and theories. It m ust account for th e hum an activity of m aking judg m ents based on reasons by which propositions are included in or exclu ded from th e body of scientific knowledge. The variations in th e condi tions for justification m ust be accounted for. O bservations lead to the form ulations of laws and theories justified by criteria of em pirical con firm ation.
B ut w hen a theory after undergoing repeated alteratio n and extension fails to account for the phenom ena th a t it is supposed to explain its con ceptual fram ew ork m ay be replaced by another and a theory u n d er the new conceptual fram ew ork is form ulated to explain the phenom ena. The difference is a very significant one for the change of th e conceptual fram ew ork indicates a deep or revolutionary change in our p o rtray al of nature. Compare th e following tw o situations in th e history of che m istry: (a) The changes in theories explaining th e stru ctu re and substi tution-réactions of benzene, and (b) the changes in th e theories explain ing combustion, especially in gases. In th e first we had a series of th e ories all w ithin the conceptual fram ew ork of organic chem istry, th e new theoretical idea th a t em erged was th a t of the rin g stru ctu re of benzene. W hereas in the second, the series of theories w hich w ere under th e con ceptual fram ew ork of the phlogiston notion steadily became extrem ely complicated and requ ired so much im agination to ren d er them consistent th a t the whole fram ew ork was dispensed w ith and combustion was b ro u g ht under a new conceptual fram ew ork of the interaction of atoms of gases. There was no longer conservation of phlogiston, th ere w as con servation of m atter in combustion. It is im portant to note th a t th e criteria embedded in both these conceptual fram ew orks w ere th e same, only one happened to be a not clearly com prehensible picture of the world. In a sense then, conceptual fram ew orks are subject to em pirical rejection; b u t it is not a straightforw ard em pirical test to w hich they are subject, it is ra th e r a gradual m ovem ent tow ards em pirical disutility. It is not so m uch a w rong picture of n atu re as one w hich is incom prehensible and fading.
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We m ust now look at another situation in th e h istory of science. The replacem ent of A ristotelean physics by G alilean physics constituted a transform ation of th e conceptual fram ew ork. B ut in this situation, unlike the previous example, the criteria em bedded in th e conceptual fram ew ork w ere different. There was a shift in the ontological criterion from th e concept of an object as belonging to some n a tu ra l class to th e concept of an object as an extended body in a sp atial and tem poral system. And th e essentially teleological dynam ical postulate of A risto telian physics was given up in favor of a geom etrical description of change. There w as no clear form ulation of a dynam ical principle in G a lilean physics. It did not come till the form ulation of N ew ton’s second law of motion. W hat we see h ere is a change of conceptual fram ew ork in w hich the v ery criteria of objectivity and causality w ere tra n sfo r med. Thus this w as a revolution in science w hich not only altered th e theories of physics b u t also th e v ery criteria of intelligibility w hich constitute explanation. It w as not ju st a revolution in physics b u t in th e epistemology of physics.
The explanatory principles of science are justified by em pirical confirm ation in the first instance. B ut la ter justifications come th rough the conceptual fram ew orks subsum ing already existing, successful th e ories. These provide justification b y reason of th e fact th a t some criteria of justification are im plicit in them . B ut th e conceptual fram ew orks m ay alter, and in some instances of these alteratio ns th e criteria em bedded in them are altered. H istory of science in its accounting of th e developm ent of scientific thought m ust disclose not only the facts of discovery and th e conclusions accepted or rejected thereby, but, also th e m ethodological grounds upon w hich th ey w ere based. Thus a h isto ry of science w hich ignores these variations in th e schemes of justification cannot b u t fail in its appointed task.
