The arguments about these rival ontological and epistemological views cannot be safely left or judged without first looking more closely at the complex relationship between the general analytical interests of philosophers and the more specific intellectual concerns of working scientists themselves. For the degree to which each view about the reality of scientific entities and facts can carry conviction depends substantially on what branches of science are at issue.
As the focus of philosophical attention has shifted historically from one scientific terrain to another, so, too, have the relative degrees of plausibility of these rival positions varied. Scientific enterprise will be considered that which has dominated recent debate in the philosophy of science, viz. , the formal structures of scientific theory and the processes of conceptual change. It will soon be clear that the philosophical problems to which these two aspects, respectively, give rise are correlative and complementary–the one being static, the other being dynamic.
Since 1920, most analytical philosophers of science have explicitly based their program on a presupposition inherited from Descartes and Plato, viz. , that the intellectual content of any natural science can be expressed in a formal propositional system, having a definite, essential logical structure–what a leading American philosopher of science, Ernest Nagel, concisely called “the structure of science” in his book of that title (1961).
One immediate inspiration of this program was the work of David Hilbert, a late 19th-century mathematician. To make the methods of mathematical proof more explicit and more perspicuous and thus more rigorous, Hilbert employed the techniques of formalization, a reduction to relations while disregarding the nature of the relata, and axiomatization, a tracing of entailments back to accepted axioms.
The same techniques were taken over into the philosophy of mathematics by a pioneer German logician, Gottlob Frege, and into symbolic logic by Bertrand Russell and his collaborator Alfred North Whitehead; and, from 1920 on, the Viennese Positivists and their successors attempted to employ them in the philosophy of science also, hoping to demonstrate the validity of formal patterns of scientific inference by the straightforward extension of methods already familiar in deductive logic.
According to the resulting program, the primary task for the philosophy of science was to repeat in quite general terms the kind of analysis by which, in the science of mechanics, Heinrich Hertz, the formulator of electromagnetic wave theory, had already sorted out the formal aspects of science from its empirical aspects. The program was founded on the expectation that it would be possible, first, to demonstrate the existence of formal structures that were essential to any science, properly so-called, and second, to identify the nature of scientific laws, principles, hypotheses, and observations by their characteristic logical functions.
Once this had been done, rigorous formal definitions could then be given of validity, probability, degree of confirmation, and all of the other evidential relations involved in the judgment of scientific arguments. Looking beyond the internal structure of inductive logic, the dubious equation of scientific laws with empirical generalizations has also been criticized on the ground that it treats the content of those laws as matters of happenstance, far more accidental or contingent than those expressed in any genuine law of nature.
In the opposing view, the explanatory force of, say, the physicist’s law of inertia is totally different from that of such a generalizing statement as “All swans are white”; and one can learn nothing about the validity of actual physical arguments unless his philosophical analysis respects that crucial difference. It has not proved easy, however, to analyze the formal structure of the sciences in any less abstract manner than that of the Viennese Positivists or to give a true representation of the working language and arguments of science.
In his Essay on Metaphysics (1940), R. G. Collingwood, a British philosopher and historian, made one striking attempt, in which the formal structure of intellectual systems was explained in terms not of direct entailments between more or less universal propositions but rather of mutual presuppositions between more or less general concepts. In this account, the principle of inertia was not the most universally true assertion in dynamics but was, rather, the most generally applicable presupposition, or principle of interpretation.
Such an account has the merit of explaining why, within a particular science, certain formal patterns of argument carry the apparent necessity that they do; but at the same time it lays itself open to the charge of yielding too much to relativism and so of destroying the objectivity of scientific knowledge by giving the impression that the conceptual structures of science are imposed on phenomena by the arbitrary choice of the scientific theorist himself. Processes of intellectual and conceptual change. Conceptual change and the development of science
The problem of conceptual change has recently come back to the fore. The crucial question it poses is: “What is a concept? ” In the heyday of Logical Empiricism, that question had largely been disregarded. Following the example of Frege, the Viennese Positivists had condemned any tendency to regard the philosophy of science as concerned with scientific thinking–which was in their view a matter for psychologists–and had restricted themselves to the formal analysis of scientific arguments. This preoccupation with logic was also reflected in their view of concepts.
To interpret a concept such as force as referring either to a feeling of effort or to a mental image could lead, they argued, only to confusion. Instead, the philosopher must equate concepts with the terms and variables appearing in the propositional systems of science and define them, in part by reference to their roles in the formal structures of those propositional systems–thus fixing their systematic import–and in part by reference to the specific events and phenomena they are used to explain–thus fixing their empirical import.
In the 1920s and 1930s, accordingly, all substantive philosophical questions about the concepts of science were dealt with summarily: they were simply translated into logical or linguistic questions about the formal roles and empirical references of technical terms and mathematical variables.
Viewed from this alternative standpoint, the philosophy of science will begin by identifying the different styles of explanation characteristic of different sciences or of different stages in a given science and will recognize how those differences in explanatory style reflect the characteristic problems of different scientific fields and periods. So considered, empirical generalizations and descriptive classifications will serve to organize the empirical data of science in a preliminary way; but serious theoretical interpretation can begin only after that point.
The central philosophical task now is to analyze, clearly and explicitly, (1) the standards by appeal to which scientists have to decide whether or not some interpretation is legitimate, justified, and conclusively established and (2) the considerations that justify giving up one currently accepted interpretation in favour of an alternative, novel one. The first of these questions is one that the Logical Empiricists set out to answer in their own manner.
They treated the empirical data and the theoretical principles of science as being connected by purely logical relations and attempted to define the required standards in terms of a formal theory of confirmation, corroboration, or falsification. The second question is one that they never seriously tackled. Instead, they assumed that one could, first, work out a quantitative index of acceptability for individual theories taken separately and, afterward, use this as a scale for measuring and comparing the merits of rival theoretical interpretations.
By now, however, it is evident that, when biophysicists, say, abandon one theoretical approach in favour of another–as being more fruitful from the standpoint of biophysics–the considerations that lead them to do so are by no means analyzable in formal terms alone. On the contrary, the ability of a biochemist, say, to judge whether or not such a change in approach will effectively help to solve his theoretical problems is one of the most severe assessments of his substantive grasp of what biochemistry is about.
In this way, the shift of attention from the propositions of science to its concepts is making philosophers more aware of the extent to which theoretical understanding involves the reinterpretation of empirical results, not merely their formal transformation. Similarly, the problem of conceptual change is raising questions about the processes by which theoretical interpretations succeed one another and about the procedures of conceptual judgment that are applied in the rational development of a science.
These questions are currently under active discussion, and several lines of attack are being considered, none of which has finally established itself. At one extreme, there are some who still regard theoretical concepts and principles as organized into compact, logical systems and who attempt to define the alternative standpoints of different sciences as the consequences of different basic premises or presuppositions.
Having adopted this systematic approach, the investigator then discovers that conceptual change at a fundamental level finds adequate scope only through the replacement of one complete formal system by another, distinct and separate successor system. As a result, fundamental theoretical change is, in this view, intelligible only as the outcome of thoroughgoing intellectual revolutions, in which one entire theoretical system–axioms, principles, criteria of relevance, standards of judgment, and all–is swept aside in favour of another.
Whichever alternative is adopted, one point must be kept in mind: the moment that problems about the changing theoretical organization of science begin to be treated in an authentically developmental manner, philosophical inquiries are given a quite new direction. This step compels one to view all questions about the logical structure and propositional systems of science against a broader historical background. In this new context the natural sciences are seen not as static formal structures but as rational enterprises characterized by certain typical intellectual procedures or movements.