DOI 10.1007/s11229-009-9588-7
Reichenbach on the relative a priori and the context
of discovery/justification distinction
Samet Bagce
Received: 13 May 2009 / Accepted: 8 June 2009 / Published online: 8 July 2009 © Springer Science+Business Media B.V. 2009
Abstract Hans Reichenbach introduced two seemingly separate sets of distinctions in his epistemology at different times. One is betweenthe axioms of coordinationand
the axioms of connections. The other distinction is betweenthe context of discovery
andthe context of justification. The status and nature of each of these distinctions have been subject-matter of an ongoing debate among philosophers of science. Thus, there is a significant amount of works considering both distinctions separately. However, the relevance of Reichenbach’s two distinctions to each other does not seem to have enjoyed the same amount of interest so far. This is what I would like to consider in this paper. In other words, I am concerned with the question: what kind of relationship is there between his two distinctions, if there is any?
Keywords Hans Reichenbach·Philosophy of science·The axiom distinction·The
relative a priori·The context distinction
1 Introduction
Hans Reichenbach (1891–1953) introduced two seemingly separate sets of distinctions in his epistemology at different times. One is betweenthe axioms of coordinationand
the axioms of connectionshe introduced in hisThe Theory of Relativity and A priori Knowledge(TRAK) (1920). This distinction is introduced in the context of a given scientific theory.
An earlier version of this paper was delivered at the conference,A Philosopher of Science in Istanbul: Hans Reichenbach, Bogazici University, May 8–9, 2008.
S. Bagce (
B
)The former are not empirical statements. One thus cannot test them empirically alone. The axioms of coordination should be laid down before one can determine empirically the relevant terms and concepts in the theory. The latter, on the other hand, are empirical statements in the traditional sense, describing empirical regular-ities. He introduces this distinction in order to argue that the traditional empiricism is at fault in not recognising the constitutive role in obtaining objective knowledge of Kant’s notion of a priori. So, the axioms of coordination are to play that role. By doing so, Reichenbach relativised Kant’s notion of a priori.
The other distinction is betweenthe context of discoveryandthe context of justifica-tionhe presented in hisExperience and Prediction(E&P) (1938). Reichenbach in the first chapter of his bookE&Pcharacterises epistemology as having three fundamental tasks:the descriptive,criticalandadvisory tasks. In this section he describes what these three tasks of epistemology are, and points to a particular difficulty of logical empiricism. In order to overcome this difficulty, the difficulty how to construct a the-ory of knowledge being both “logically complete and in strict correspondence with the psychological process of thought”, he distinguishes the task of epistemology from that of psychology. He employs the termrational reconstructionto indicate the task of epistemology. He then introduces “the termscontext of discoveryandcontext of justificationto mark this distinction”. He later identifies the context of justification as the proper domain of epistemology.
The status and nature of each of these distinctions have been subject-matter of an ongoing debate among philosophers of science. Thus, there is a significant amount of works considering both distinctions separately. Some honour them by seeing them as legitimate. Some try to abolish. There is no need to list here all the studies conducted until now. However, the relevance of Reichenbach’s two distinctions to each other does not seem to have enjoyed the same amount of interest so far. This is what I would like to consider here. In other words, I am concerned with the question of what kind of relationship there is between his two distinctions, if there is any.
2 The first distinction: TRAK and the philosophy of space and time
Reichenbach’sTRAKgrew out of such a need. InTRAKReichenbach argues that the theory of relativity makes it impossible for one to maintain the synthetic a priori character of all the principles Kant had thought. So, one of the basic aims Reichenbach has inTRAKis to refute Kant’s philosophy. The other one is to provide a reinterpreta-tion of Kant’s philosophy so that it would still be compatible with the relativity theory, as well as by means of which he would provide a good philosophical account of the relativity theory.
But before going any further, let me ask the following question: what did Kant do that required such a refutation? To answer the question requires us to consider Kant’s philosophy briefly. Kant articulates an analysis of what counts as a genuine knowl-edge, i.e. scientific knowlknowl-edge, in hisMetaphysical Foundations of Natural Science
(MFNS) (1786/1970). He provides his account in terms of two particular theories, Newtonian physics and Euclid’s geometry, which, in turn, is assumed as a background by Newtonian physics. In other words, he considers these two theories as providing us with what counts as genuine scientific knowledge.
Kant’s account of scientific knowledge is based upon a distinction betweenpureand
empirical, orformandcontentparts. Kant maintains that the pure part entirely consists of synthetic a priori judgements. Synthetic a priori judgments are actually obtained by the synthesis resulting from applying the pure concepts of the understanding to the content provided by the pure intuitions of the faculty of (human) sensibility. The pure forms of intuition together with the pure categories—yielding the synthetic a priori judgements—which, in turn, constitute the pure part of knowledge, then represent the veryconditions of the possibilityof the empirical part. Without the former, the latter cannot have well defined meaning, and any relation to objects, that is, truth values. So, one can have nojudgement of experience, unless one has laid down the pure part in the first place. Thus, the pure part reallyconstitutesthe objects of the judgements of experience, i.e. genuine knowledge. This is why Kant regards them asconstitutive. However, they are not only constitutive; they are at the same time to make synthetic a priori judgment as necessarily and unrevisable true for all times.
According to Kant, the pure part in the case of Newtonian physics contains Euclid’s geometry, or more generally the whole applied mathematics required by the same the-ory, Galilean kinematics, or the absolute simultaneity and classical law of velocity addition, and Newton’s laws of motions. These are to provide the very background for Newtonian physics to formulate some specific laws of nature. As an example of these specific laws of nature, the law of universal gravitation can be cited. Not only this kind of laws, but any specific laws of motion that are to be obtained in terms of the Newtonian laws of motion are, in turn, to form the empirical part (seeFriedman (1999), p. 61).
However, the bookTRAKhas a more interesting consequence that the theory of relativity also makes possible to provide a reinterpretation of Kant’s conception of a priori, and by such a reinterpretation one can see what is right in Kant’s epistemology and at the same time what is wrong in the naïve empiricism, i.e. logical positivism.
Thereby Reichenbach differentiates two separate meanings of Kant’s notion of a priori:
(i) necessarily and unrevisably true for all times;
(ii) constitutive of the concept of an object (see,1920, p. 48).
Reichenbach rejects the first meaning of a priori, but considers the second one as important. While he is clarifying these meanings, he introduces his famous distinction betweenthe axioms of coordinationandthe axioms of connection(see,1920, p. 54).
By accepting the second meaning, he could provide a well articulated philosophical account of the general theory of relativity. He thereby could protect the theory against the neo-Kantians by maintaining that what Kant had once thought of some principles as a priori is true, but in the restricted sense of the a priori: we need those principles just to constitute the objects of experience, or better, these principles are just constitutive principles. Moreover, this was quite befitting with his general philosophical aim: to point out and account of the presence of the personal or subjective elements in human knowledge contributed by human beings, or reason.
Reichenbach by his distinction betweenaxioms of coordinationandthe axioms of connectionaims at providing a more specific account of the character and the status of these constitutive principles. Briefly for Reichenbach, the axioms of coordination are themselves not empirical statements and one cannot empirically test them alone. However, they are the principles that make it possible for scientific theories to have any relation to reality and empirical content. Therefore, before we lay down these axioms, no meaningful question of truth or falsity of scientific theories can be raised. They are necessary assumptions for doing any scientific investigation and for understanding the world.
These axioms are necessary to determine what objects, properties and so on, our scientific theories talk about. Therefore, they are to provide a framework for empirical theorising, and thus, they are constitutive of the objects of experience. Once these axioms are laid down and thereby a specific subject-matter is defined, one can then formulate the axioms of connection that make specific empirical claims about the subject-matter. The axioms of connection are empirical statements in the traditional sense, describing empirical regularities.
When Reichenbach sees the axioms of coordination as being constitutive of the objects of knowledge, he agrees with Kant on the presence of a priori elements or principles in human knowledge. In other words, Reichenbach allows some subjective elements in human knowledge provided by reason as only to constitute the objects of knowledge, but not make our claims concerning these objects necessarily and unre-visably true.
of connection (seeFriedman(1999), p. 61). This is Reichenbach thinks exactly what Kant got right. So, Reichenbach believes that Kant’s articulation of human knowledge is correcthistorically.1
In the case of the special theory of relativity (STR), Reichenbach maintains that Euclidean geometry, Lorentzian kinematics, that is, the structure of Minkowski space-time, are the axioms of coordination. On the other hand the axioms of connection in this theory, theories of particular forces and fields formulated in this structure such as Maxwell’s equations (seeFriedman(1999), p. 62).
In the context of the general theory of relativity, Reichenbach says that we have changed once again our framework and the axioms of coordination. “Now only the infinitesimally Lorentzian manifold structure—space-time topology sufficient to ad-mit some or another (semi-) Riemannian metric—is constitutively a priori: the par-ticular (semi-) Riemannian metrical structure realized within this framework then is determined empirically from the distribution of mass-energy, and thus the specific principles of metrical geometry now count as axioms of connection” (seeFriedman (1999), p. 62).
This is also according to Reichenbach to point to what is wrong with the naïve empiricism: they do not notice the role of the axioms of coordination in representing the “subjective form” of knowledge, i.e. the contribution of reason, since they claim that they can characterise all scientific statements indifferently as “derived from expe-rience”; namely, as protocol sentences. In other words, Reichenbach does not hold the view that ordinary physical objects can be constructed solely out of sense data; instead, he thinks that to do so, some constitutive principles are also required. He does not think that there is a set of privileged sense perceptions being independent of these principles corresponding to physical objects.
However, for Reichenbach, the axioms of coordination are not adopted for once and all. They can be developed, revised or given up with the progress of empirical science, that is, in the light of, and under the pressure of empirical findings. This is in fact what we have learnt from the theory of relativity: we have changed our axioms of coordination and, therefore, our concept of object of knowledge in moving from classical physics to relativity theory (1920, p. 94). As the development of relativity theory shows, the axioms of coordination are not unrevisable fixed points of empirical inquiry.
As for The Philosophy of Space and Time (PST), (1928), published eight years afterTRAK, is a book in which Reichenbach engages to unify certain ideas he had previously held with some modifications. It is an elegant work, and by employing better tools he provides his own account in addition to Helmholtz’s and Poincaré’s views concerning geometry with an analysis of Einstein’s special and general theories of relativity, some of which was already given in hisAxiomatization of the Theory of Relativity(ATR), (1924).
Some of these ideas include the distinction between universal and differential forces,normal systems, the synonymy ofequivalent descriptions,the principle of the relativity of geometry, the distinction betweeninductiveanddescriptive simplicity, the
requirement of postulating coordinative definitions beforehand, the conventionality of coordinating definitions, the conventionality of metrical simultaneity, an analysis of the logical structure of relativity theories in terms of causal relational properties.
Reichenbach begins his work by establishing the interdependence between alterna-tive ways of measuring length and alternaalterna-tive geometries, and thereby maintaining the same kind of relationship between properties and laws. This is to enable Reichenbach to argue that alternative systems of definitions and laws that account for the same empirical facts make the same claims and the same empirical content. In other words, these descriptions provided by these alternative systems of definitions and laws are equivalent ones. Thus, he no longer holds that relativity theory establishes a particular geometry as a background to this physical theory. But here by definitions Reichenbach meanscoordinative definitions, that is, they are specifying certain physical procedures to determine the values of quantities.
Reichenbach also brings in Helmholtz’s idea of visualisation into discussion to argue against the view that pure visualisation has some normative function by main-taining that “the normative function of visualization is not visual but of logical origin” (1928, p. 91).
PSTin general does not deviate much concerning Reichenbach’s treatment of space and geometry from the one given inTRAK: each of the given theories, Newtonian, STR and GTR has a certain group of transformations that leaves certain things invariant. And each of such groups provides us with a range of possible and equivalent descrip-tions of nature. Reichenbach thinks that those elements remaining invariant are the elements that mark out the range of these possible and equivalent descriptions, and are the constitutive elements, the contributions of reason so to speak, that is, the definitions of coordination. And they also indicate that within the range of possible descriptions, the choice of one system over another one is arbitrary, that is,conventional.
For Newtonian physics the relevant group of transformations is the Galilean group, and particular fields (of gravitational force, distribution of mass and etc.) formulated in this structure are empirical statements. In STR, it is the Lorentz group and particular fields defined in this structure such as the electromagnetic, the distribution of charge and etc., are the axioms of connection. And in GTR, it includes one-one bi-differen-tiable transformations, i.e. the underlying topology is constitutive but the metric of physical space is empirically determined (seeFriedman(1999), p. 66).
In PST, there does seem to be one striking change in Reichenbach’s language and epistemology. The termconventionis not regarded as ill reputed any more, and employed instead of a priori.2 All his references inPST to a priori are in critical character. This may be taken to indicate a certain break with Kant’s epistemology. In PST, Reichenbach seems to have given up his association with neo-Kantianism (1928, p. xii). Thus, the epistemology underlyingPSTis intended to be basically more empiricist: the conventional elements in science are just the non-observational or the-oretical ones. The only facts are the observable facts; all the rest is the “contribution of reason”. The distinction inTRAKbetween the elements of reason/facts, or if you like theconventional/factualdistinction, is transformed into thetheoretical/observational
one. But inTRAK, the former part of the first distinction is not identical to that of the latter’s; instead it is drawn within the realm of the theoretical: certain elements of theoretical structure, for example the choice of rest system and of inertial system, are conventional, other theoretical elements, such as the choice of metric, are not.
Reichenbach seems to have developed two different epistemological positions, though they are complementary to each other:
i) the earlier one, given inTRAKand ii) the later one, given inPST.
However, there is the same concern underlying both positions. This is his concern to point to, and to account of, the presence of the elements in human knowledge con-tributed by reason, or subjective, conventional if you like—though Reichenbach does not use this appellation to describe his position inTRAK. He holds inTRAKthat the form/content (convention/fact) distinction is essential for epistemology as well as the philosophy of science. InE&Phe says that “the presentation of volitional—conven-tional that is—decisions contained in the system of knowledge constitutes an integral part of the critical task of epistemology” (1938, p. 9). Reichenbach’s positions both inTRAKandPSTare neither strictly Kantian nor strictly naïve empiricist but inPST
he seems to have liked to be less Kantian, and more empiricist.
3 The second distinction: experience and prediction
In Experience and PredictionReichenbach spells out the epistemology underlying
PSTand this is the book in which Reichenbach intends “to show the fundamental place which is occupied in the system of knowledge by this concept [the concept of probability] and to point out the consequences involved in a consideration of the probability character of knowledge” (1938, p. vi).
In the very first section of the first chapter, Reichenbach characterizes epistemology as having three fundamental tasks:the descriptive,criticalandadvisory tasks. In this section he describes what these three tasks of epistemology are, and points to a partic-ular difficulty of logical empiricism. In order to overcome this difficulty, the difficulty how to construct a theory of knowledge being both “logically complete and in strict correspondence with the psychological process of thought”, he distinguishes the task of epistemology from that of psychology in the descriptive task of epistemology:
What epistemology intends to do is to construct thinking processes in a way in which they ought to occur if they are to be ranged in a consistent system, or to construct justifiable sets of operations which can be intercalated between the starting point and the issue of thought-processes, replacing the real inter-mediate links. Epistemology, thus, considers a logical substitute rather than real processes (1938, p. 5).
To illustrate the point he appeals to an example:
The way, for instance, in which a mathematician publishes a new demonstration or a physicist his logical reasoning in the foundation of a new theory, would almost correspond to our concept of rational reconstruction; the well-known difference between the thinker’s way of finding this theorem and his way of pre-senting it before a public may illustrate the difference in question (1938, p. 6).
He then introduces “the termscontext of discoveryandcontext of justificationto mark this distinction” (1938, pp. 6–7). He later identifies the context of justification as the proper domain of epistemology (1938, p. 7 and 382).
However, he immediately warns off the reader by saying that “even the way of pre-senting scientific theories is only an approximation to what we mean by the context of justification. Even in the written form scientific expositions do not always correspond to the exigencies of logic or suppress the traces of subjective motivation from which they started” (1938, p. 7).
This descriptive task a bit further down in the book is supplemented by the second task of epistemology, that is, the critical task in which “the system of knowledge is criticised; it is judged in respect of its validity and its reliability. This task is already partially performed in the rational construction, for the fictive set of operations occur-ring here is chosen from the point of view of justifiability; we replace actual thinking by such operations as are justifiable, that is, as can be demonstrated as valid” (1938, p. 7). However, they are still different because “even the rational reconstruction contains unjustifiable chains”.
It is interesting to see that the next time Reichenbach refers to this distinction is nearly at the end of the final chapter on probability and induction of the book. Before he brings in the distinction he talks about an objection to his account of induction “as an interpolation, as a method of continual approximation by means of anticipa-tions”, the objection that Reichenbach’s theory of induction “may be good enough for the subordinate problems of scientific inquiry, for the completion and consolidation of scientific theories. Let us leave this task to the artisans of scientific inquiry—the genius follows other ways, unknown to us, unjustifiable a priori, but justified after-wards by the success of his predictions” (1938, pp. 379–381). The objection basically amounts to be claiming that all the important works of great scientific minds cannot be achieved only by the methods of simple induction and the employment of diagrams and statistics.
To this objection Reichenbach’s reply runs as follows: “I know … that the working of their [the great men of science] minds cannot be replaced by directions for use of diagrams and statistics. I shall not venture any description of the ways of thought followed by them in the moments of their great discoveries; the obscurity of the birth of great ideas will never be satisfactorily cleared up by psychological investigation” (1938, p. 381). However, he does not see these facts as constituting any objection to his theory of induction “as the only means for an expansion of knowledge”.
We emphasized that epistemology cannot be concerned with the first but only with the latter; we showed that the analysis of science is not directed toward actual thinking processes but toward the rational reconstruction of knowledge. It is this determination of the task of epistemology which we must remember if we want to construct a theory of a scientific research.
What we wish to point out with our theory of induction is the logical relation of the new theory to the known facts. We do not insist that the discovery of our new theory is performed by the reflection of a kind similar to our expositions; we do not maintain anything about the question of how it is performed—what we maintain is nothing but a relation of a theory to facts, independent of the man who found the theory. There must be some definite relation of this kind, or there would be nothing to be discovered by the man of science (1938, p. 382).
Reichenbach then asks the following question: why was Einstein’s theory of gravi-tation a great discovery, even before it was confirmed by astronomical observations? His answer is that:
[B]ecause Einstein saw –as his predecessors had not seen- that the known facts indicate such a theory; i.e., that an inductive expansion of the known facts leads to the new theory. This just what distinguishes the great scientific discoverer from a clairvoyant. The latter wants to foresee the future without making use of induction; his forecast is a construction in open space, without any bridge to the solid domain of observation, and it is a mere matter of chance whether his prediction will or will not be confirmed. The man of science constructs his forecast in such a way that known facts support it by inductive relations; that is why we must trust his prediction. What makes the greatness of his work is that he sees the inductive relations between different elements in the system of knowledge where other people did not see them; but it is not true that he predicts phenomena which have no inductive relations at all to known facts. Scientific genius does not manifest itself in contemptuously neglecting inductive methods; on the contrary, it shows its supremacy over inferior ways of thought by better handling, by more clearly using the methods of induction, which always will remain the genuine methods of scientific discovery” (1938, pp. 382–383).
“there would be nothing to be discovered by the man of science”. He also iterates this point by saying that “the inductive connections of modern physics are constructed analytically…” (1938, p. 385). We can and should be interested in providing a rational account of how these relations, which are supposedly exist between the facts and the theory or that particular new piece of knowledge, are obtained.
Reichenbach also adds the remark that the difference of the context of justification from the context of discovery is not restricted only to inductive thinking alone. The same distinction can also be made with respect to deductive operations of thought (see 1938, p. 383). He states a particular example in geometry, “the construction of a trian-gle from three given parameters”. He maintains that “the objective relations from the given entities to the solution and the subjective way of finding it are clearly separated for problems of a deductive character; we must learn to make the same distinction for the problem of the inductive relation from facts to the theories” (1938, p. 384).
Reichenbach stresses the difference between the logical relations existing between the set of the givens and the conclusion and the way one sees or discovers those relations in the problems of deductive character. Although, as it is pointed out, the discovery/justification distinction seems to have been present before Reichenbach reintroduced in his E&P,3 it seems that Reichenbach takes his cue for the context distinction from this difference in deduction. This characterisation thereby makes the distinction as the one between factual and formal/normative.
Reichenbach by this distinction basically intended to show that the psychological, sociological, cultural origins of statements, theories have nothing to do with the way of determining their truth values, and thereby having no epistemological concern. What is relevant epistemologically is the possibility of confirming statements.
Giere argues that this distinction is a matter as deeply personal as it was philosoph-ical. He thinks that “there may well exist additional documentary evidence regarding Reichenbach’s personal motivations for insisting on a distinction between discovery and justification around 1935” (1999, p. 230). So, Reichenbach wanted to have a sci-entific epistemology dictating as a precondition that rules out the possibility of Jewish or any national or culturally identifiable science. Giere also thinks that “that had to be a very useful stance for anyone in his position”, given the historical evidence such as he was called back to Berlin prior to 1938 and he was looking for safe heaven in the States, as well as completed the book in English in 1934–1937 (see1999, pp. 13–15 and 227–230).
There is one more role for this distinction to play: Reichenbach criticises inE&Pa doctrine to which a number of early positivists had been committed: phenomenalism. The roots of Reichenbach’s rejection of phenomenalism go back to his alliance with Kantianism: inTRAK, he rejects the synthetic a priori status of Euclidean geometry and of causality, but he retains the idea ofa priorito play an essential role in con-stituting objects of knowledge. From this, one can safely say that he did not hold the view that ordinary physical objects could be constructed solely out of sense data or that statements about such objects are logically equivalent to a finite set of “proto-col” statements; instead, he holds that to do so, some sort of constitutive principle
was also required. Since his theory of empirical confirmation is probabilistic, then he thinks, it is easy to adopt a kind of empiricism and to maintain a consistent empiricist epistemology without appealing to any form of phenomenalism.4
However the distinction is introduced by Reichenbach not as a logical conclusion of any series of arguments. This is also the case with the first distinction as well. It is introduced as apreconditionfor doing a normative epistemology which deals with the “three predicates of propositions”, meaning, truth-value, and weight (probability). It is clear that none of these predicates has anything to do with questions concerning the psychological, sociological, cultural origins of propositions or theories. Put it in another way, the way a particular theory is discovered or constructed has no bearing upon the way it is to be justified. So the legitimate domain of any epistemology that aims at providing a scientifically articulated account of human knowledge is not the context of discovery, but that of justification.
4 The relationship between Reichenbach’s two sets of distinctions
Let me begin by asking the following question: Is there any relation between these two sets of distinctions Reichenbach introduces? There does not appear to be so. Rei-chenbach never states that these two distinctions are in one way or other related to each other. But can they be related by asking the question of justification concerning the definitions (earlier axioms) of coordination, or conventions?
One may think that this is a legitimate question given Reichenbach’s original defi-nitions of the descriptive and critical task of epistemology. However, one can immedi-ately raise an objection here: their justification cannot arise given the fact that they are the ones that facilitate the normative justification procedure. Prior to this distinction no question of justification can meaningfully be asked. So they cannot be subjected to any procedure of justification. But let’s assume that a permission be granted to ask the aforementioned question just to see what Reichenbach can say on the issue.
With respect to this issue, the justification of the axioms or definitions of coordina-tion, Reichenbach in his earlier epistemology says almost nothing except that “… the principles of coordination are determined by the nature of reason; experience merely selects from among all possible principles” (1920, p. 87). And he also adds that “the contribution of reason is not expressed by the fact that the system of coordination
4 Moreover, Reichenbach assumes a certain link between the definitions (earlier the axioms) of coordi-nation in each of Newtonian physics, STR and GTR, and thereby the mathematical structures associated with each theory and the empirical findings or experience. However, the link between these definitions and the invariance groups is not something to be assumed, but something to be demonstrated (seeFriedman
contains unchanging elements, but in the fact that arbitrary elements occur in the system” (1920, pp. 88–89).
In his later epistemology, there seems to be one more thing Reichenbach could say: these definitions of coordination or conventions, say, in the case of GTR, are cho-sen simply because they have produced a system which contains no universal forces, i.e. normal system. Although his theory of probability is defective, especially with respect to the distributing the prior probabilities, he could still argue for the claim that by appealing to the idea of induction and descriptive simplicity, we can justify our choice of these conventions over others as the best posits exhibiting the objective inductive relation from the known facts to the theory.
But in this case Reichenbach would face some serious difficulties. The first one is that one cannot guarantee that the so called objective relations between the known facts and the theory can only accounted for and discovered simply by the application of inductive methods. There are other formal methods, such as group theory, deductive quasi-empirical methods, that might be at work in establishing the link.
The second one is that Reichenbach’s account of induction cannot be powerful enough to lead us necessarily to one unique scientific theory. It is perfectly possible the same objective relations can also be captured by more than one scientific theory. After all, there are in principle infinitely many ways to generalise on the basis of the given empirical data.
This is a possibility that Reichenbach himself does not rule out, and because of this fact, Reichenbach introduces his definition of equivalent descriptions and of synon-ymy. According to Reichenbach, all these equivalent descriptions express the same physical content, but in different languages. The question here is not which of the equivalent descriptions is the trueone; for that question is ill-formed: they all are either true or false. If one of these equivalent descriptions contains no universal force, (or, say, it involves a normal system), according to Reichenbach, it is the one that we should choose. Justification of choosing the normal system as the preferred description is given by means of the principle of descriptive simplicity.
But this is the point where Reichenbach goes wrong when he says that the objective relations can only be discovered by the application of inductive methods. One of the equivalent systems is denying the existence of some universal forces, and the other one positing their existence. Since one cannot empirically confirm or falsify such claims, we cannot maintain that one has obtained such objective relations by means of the theory. The only way one can argue for the objectiveness of such claims is through justifying the theory altogether in question, that is, the one that denies the existence of such forces.5
This means that one has to have constructed the theory beforehand in order to argue for the objective character of the relations between the theory and the known facts. Otherwise it would be an impossible task to achieve. In other words, in Reichenbach’s case, he should have committed to the truth of the relativity theory; he could then argue that those objective relations between the known facts and the theory could be obtain-able by induction alone. It is clear that Reichenbach was only interested in justifying
the choice of certain conventions lying at the very basis of the relativity theory. Put it in other way, Reichenbach’s account of knowledge outlined in hisE&Pis supposed to yield a justification for scientific knowledge exemplified by the relativity theory. This is exactly the primary reason for Reichenbach to introduce the context diction: to safeguard those coordinative definitions or conventions upon which the theory was erected so that they could not be subjected to a further justification. This is the point where the relationship between these two sets of distinction seems to arise. Because of this, Reichenbach seems to have introduced separately these two different sets of the distinctions.
The justification of the relativity theory is an empirical matter, and depends upon the number of the correct predictions it makes. The relativity theory had made some correct predictions by the time Reichenbach got interested in the theory. There is no question that Reichenbach’s trust in the theory must have been affected by these pre-dictions. However, these correct predictions cannot be the only reason for his trust in the success and truth of the theory. Howard outlines other important factors in the following way:
It is, of course, not surprising that three [Schlick, Reichenbach and Carnap] bright, technically sophisticated, young philosophers would be excited by the relativity, especially in the wake of the wave of public interest after Eddington’s 1919 eclipse expedition yielded confirmation of the predicted bending of the light near the sun. With its radical challenge to received views about the nature of space and time, and gravitation, with its implicit challenge even to the method whereby physics had earlier been done, general relativity suited the rebellious temperaments of young thinkers who were coming of age at a time of political and cultural upheaval and eager to lead a revolt against the philosophy of their elders similar to the revolt then underway against the politics of their elders [...]. Certainly Schlick and Reichenbach were also attracted not only to the theory, but to its author. Einstein was more than just a world-famous scientific genius. He was a pacifist who was notorious in Germany for his early expression of doubts about German war aims. He was a socialist who was sympathetic to the aims of young Berlin student radicals, like Reichenbach [...]. He was a Jew in a Germany already showing the first signs of a vindictive anti-Semitism. How could one not be drawn to such a man and his science? How could one not seek to develop a philosophy of science that would legitimate the relativity theory’s claims to superiority over its predecessors, a philosophy of science that would be legitimated in turn by its success in thus rationalizing the achievements of relativity? (1994, p. 46).
As Howard points out, these additional factors must have played some considerable role in Reichenbach’s belief in the achievement of the theory. These factors are not something that can be inferred by the logical analysis and justification of the theory. They are the so called “social” elements that have contributed to his belief in the theory. Thus, the context distinction is already blurred.
knowl-edge exemplified by Newtonian physics as well as Euclid’s geometry. As pointed out by Reichenbach himself, Kant’s theory of knowledge was historical. In other words, it was with respect to these particular theories at his period. He wanted to provide an indisputable epistemological basis for the aforementioned theories so that no form of scepticism could arise. There was only one way to do so and this move to suppress any scepticism should be made right at the beginning, that is, by providing such an a priori basis for these theories which could immunise them for further justification. By this move, Kant was able to put some restriction on what aspects of the nature were know-able and to legitimise what kinds of questions were epistemologically permissible.
This is exactly the job for Reichenbach that was intended to be done by the introduc-tion of the context distincintroduc-tion so that no possible form of scepticism and any quesintroduc-tion of the origin and justification could arise concerning the coordinative definitions in the case of the general theory of relativity. Thus, his account of knowledge is too historical, with respect to a particular scientific theory, the general theory of relativity. Reichenbach, like Kant, was introducing certain restrictions to determine the domain of epistemological activity. Reichenbach’s account of knowledge becomes susceptible to the same pitfalls Kant had.
Moreover, after Kant there was a discussion about the problem of the foundation of epistemology raised by K. L. Reinhold concerning the firstCritique. This problem later was formulated as a trilemma by Jakop Friederich Fries—dogmatism, infinite regress, and psychological basis. Later on with the revival of Fries’s philosophy through the works of Leonard Nelson, the foundational problem was discussed as the distinction between genesis and validity in epistemology. Reichenbach must have been aware of these discussions. So, one reason for him to introduce the context distinction might be to provide a solution to the foundation problem then.6
To conclude: Reichenbach was not interested in how to account for the role of human creativity in providing genuine scientific knowledge; but interested in accounting for a kind of knowledge provided by a specific scientific theory. Since he was primarily interested in justifying the relativity theory, he introduced the context distinction. He was still Kantian inE&Ptoo, though much he wanted to disassociate himself from it, and the reason why Kant failed are the reasons why Reichenbach fails.
The so called personal or social or conventional elements play important roles in producing scientific knowledge. These are exactly the elements for Reichenbach that need to be pointed to and accounted of. This was the gist of his general epistemological programme. To map out what kinds of roles and how conventional, subjective or social elements in human knowledge play in constructing certain structures yielding scientific knowledge is certainly a proper job for epistemology. However, introducing certain restrictions on what aspect of nature one can know and what kinds of epistemological questions are allowable to ask is certainly not a step in the right direction in dealing with fundamental epistemological questions. By doing so, one would definitely lead to an epistemological impoverishment.
This is what writes in thePrefacetoE&Pand later forgets all about it:
The idea that knowledge is an approximate system which will never become “true” has been acknowledged by almost all writers of the empiricist group; but never have the logical consequences of this idea been sufficiently realized. The approximate character of science has been considered as evil, unavoidable for all practical knowledge, but not to be counted among the essential features of knowledge; the probability element in science was taken as provisional feature, appearing in scientific investigation as long as it is on the path of discovery but disappearing in knowledge as a definite system. Thus a fictive definite system of knowledge was made the basis of epistemological inquiry, with the result that the schematized character of this basis was soon forgotten, and the fictive construction was identified with the actual system. It is one of the elementary laws of approximative procedure that the consequences drawn from schematized conception do not hold outside the limits of the approximation; that in particular no consequences may be drawn from features belonging to the nature of the schematization only and not to the co-ordinated object (1938, p. vi).
Acknowledgements I wish to thank Alan Richardson for instructive remarks on the topic of this paper; Stathis Psillos for enlightening talks and comments on an earlier draft; and Thomas Uebel for valuable discussions and observations while formulating the problem of this paper.
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