Ernan McMullin

The Fertility of Theory and the Unit for Appraisal in Science

In both rationalism and empiricism, the two ‘classical’ forms of philosophy of science originating in the seventeenth century, it was assumed that appraisal in science had to be a matter of applying logical rules. To justify a scientific statement was to infer it from the first principles (rationalist) or the evidence (empiricist). To appraise was to certify the starting point of the inference as true principle or reliable evidence, and then evaluate the validity of the inference (deductive or inductive) drawn from it. There are two major assumptions here: first the foundationalist one that science must rest on foundational statements, themselves unchallengeable, and second, the logical one, that inferability is the proper test of a scientific claim.1 If science is to be the definitive sort of knowing that nearly everyone from Aristotle to Kant thought it could and should be, these assumptions are difficult to avoid.

Indifference principle and anthropic principle in cosmology

MUCH attention has been given in recent years to the active role played in the natural sciences, notably in physics, by ‘principles’ of very general scope. They serve to guide inquiry, indicating the direction in which successful theory is likely to lie. They are also, in Toulmin’s felicitous phrase, principles of natural order specifying in a very general way how the world is, what sorts of order we should expect to find there. Find or impose? In his Metaphysical Foundations of Natural Science, Kant gave memorable expression to one answer to this stilldebated question. The peculiar authority attributed to such principles, their ‘hard-core’ status when anomalies arise, sometimes leads them to be called ‘philosophical’ or ‘metaphysical’. And indeed their warrant does seem more than merely inductive. Their appeal is, in part at least, intuitive; it derives from their supposed self-evidence. As with the principles of Aristotelian science, once one understands them, one is expected to see that they must hold, that their violation is inadmissible. My topic here is not their epistemic status in general, but the emergence of several new, or at least partly new, principles in cosmology. By way of background, recall for a moment what is perhaps the best-known cosmological principle.’ To Descartes, as to Aristotle before him, action at a distance appeared to be out of the question. The principle of contact action demanded that the planets be moved by agencies in contact with them, spheres or vortices as the case might be. There was no direct evidence for such agencies, nor could any specific supporting empirical consequences be drawn from them. Yet natural philosophers unhesitatingly attributed existence to them. When Newton constructed a celestial mechanics around the notion of attraction, many of his contemporaries objected that he had violated a fundamental principle: attraction between planet and sun equivalently required action at a distance. Newton demurred. He too, he responded, regarded such action as ‘inconceivable’. Indeed:

The Conception of Science in Galileo’s Work

It has been remarked more than once that each generation of theorists of science makes of Galileo, the “father of modern science” by customary reckoning, a scientist after its own heart.1 Most recently Paul Feyerabend proposed that: What Galileo did was to let refuted theories support each other, that he built in this way a new world-view which was only loosely (if at all!) connected with the preceding cosmology (everyday experience included), that he established false connections with the perceptual elements of this cosmology which are only now being replaced by genuine theories (physiological optics, theory of continua), and that whenever possible he replaced old facts by a new type of experience which he simply invented for the purpose of supporting Copernicus.2

The Rational and the Social in the History of Science

If science is, at least in some sense, a social product, as almost everyone in these more relaxed Kuhnian times seems disposed to allow, may not its claims be shaped to some degree by social interests? And if these interests are themselves contingent features of the particular society, is there not an ineliminable contingency about even the most apparently secure scientific findings? How, then, can the rationality of science be said to transcend the society that produces it? And if it does not, can one still validly draw that distinction between epistemic (knowledge) and doxa (opinion) which has underlain virtually all thinking about science from Plato’s day until our own?

Comment: Duhem's middle way

Duhem attempted to find a middle way between two positions he regarded as extremes, the conventionalism of Poincaré and the scientific realism of the majority of his scientific colleagues. He argued that conventionalism exaggerated the arbitrariness of scientific formulations, but that belief in atoms and electrons erred in the opposite direction by attributing too much logical force to explanatory theories. The instrumentalist sympathies so apparent in Duhems writings on the history of astronomy are only partially counterbalanced by his view that science is progressing toward a ‘natural classification’ of the world.

Philosophy of Science and Its Rational Reconstructions

When the philosopher of science stands back from his field in order to try to situate the rapid developments of the past two decades, a variety of ways suggest themselves as to how one might best characterize these. In a lengthy article “History of science and its rational reconstructions”,1 the late Imre Lakatos proposed a four-fold division of what he regarded as the major ‘rival methodologies’: inductivism, conventionalism, falsificationism, and his own ‘methodology of scientific research programs’ (MSRP). It will be the task of this essay to evaluate this way of viewing the contemporary scene, and to propose a rather different one.

Empiricism at Sea

Ought one represent the Quine-Kuhn-Hanson-Feyerabend-Lakatos-Polanyi rejection of the logical positivist account of science that dominated the world of English-speaking philosophy in the decades between 1930 and 1960 as a rejection of empiricism itself? Is it permissible to group these critics together as though the differences between them in this context were not significant? These are the first questions that are likely to leap to the reader’s mind as he peruses Professor Feigl’s spirited defence of a threatened orthodoxy. As he reads on, another question may begin to nag him a little too. From the beginning, Professor Feigl concedes that “drastic revisions are in order”. Indeed, he admits so many of these revisions as his essay progresses that one is not altogether sure finally where to locate the substantial disagreement he believes to exist between him and those whom he is attacking. His aim, he says, is to defend “the central tenets of classical as well as of modern (or ‘logical’) empiricism” against the mistaken objections of ‘the critics of empiricism’. But as one notes the concessions he makes to these same critics, one cannot but ask whether many of the central tenets of these two forms of empiricism are not in fact being abandoned, and whether the critics are really critics of empiricism, as such, or only of two historical forms of it associated with 18th century Britain and 20th century Vienna respectively. In short, is it really empiricism that is at bay? And has not Professor Feigl, in the light of the concessions he makes, become one of the hunters himself, displaying (incidentally) an admirable openness of mind thereby?

Van Fraassen’s Unappreciated Realism

What is not often noted about Bas van Fraassen’s distinctive approach to the scientific realism issue is that constructive empiricism, as he defines it, seems to involve a distinctively realist stance in regard to large parts of natural science. This apparent defection from the ranks of his more uncompromisingly anti‐realist colleagues raises many questions. Is he really leaning to realism here? If he is, why is this not more widely noted? And, more important, if he is, is he entitled to this shyly realist concession? Does his many‐pronged attack on what he sees as the main arguments in support of realism leave him with the wherewithal?

A Clinician’s Quest for Certainty

John Gedye began his paper by quoting Simone de Beauvoir who laments the fact that words force her into rigid categories, into blacks and whites that ill match a world in shades of grey. Inexorable, then, she cries, that in such a world truth should dwindle into insignificance. This is a cryptic saying to introduce a paper which will seek to strip the clinician of his customary grey language and force him to “black and white” assertions (p. 109) and “stringent criteria of certainty” (pp. 105–106). “Only when we have no alternative…”, Gedye admonishes his fellow-clinicians “should we accept having to fall back into the ‘gray’ world of weak probabilistic arguments” (p. 109). Are we to infer, then, that in the world of the clinician truth is doomed to dwindle into insignificance? I cannot believe that this is what Gedye intended, yet this is the moral of de Beauvoir’s remark.

Logicality and Rationality: A Comment on Toulmin’s Theory of Science

Stephen Toulmin’s discussion of historical change in science makes use of a number of dichotomies that have become increasingly popular in the decade since the appearance of Kuhn’s Structure of Scientific Revolutions. One of these, that between ‘logicality’ and ‘rationality’, he sharpens more perhaps than anyone else has done, with far-reaching consequences not only for the historical sociology of science but also for the philosophy of science and for the general theory of man as a knowing being. If he is right, not only have most people been looking in the wrong direction in their attempt to circumscribe and understand the structures of human rationality, but it is not even clear that it has any structures, of the kind they were looking for, at least.