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. The formal structures of science:
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.

Bibliography1) Ernest Nagel, The Structure of Science (1961). 2) M.W. Wartofsky,
Conceptual Foundations of Scientific Thought (1968). 3) Arthur Danto and Sidney
Morgenbesser (eds.), Philosophy of Science (1962). 4) Samuel B. Rapport and
Helen Wright (eds.), Science: Method and Meaning (1964). 5) W.H. Newton-Smith,
The Rationality of Science (1981).