In the practice of science lies the key to virtue. The proposition I have enunciated is not an obvious one. Its contradictory could conceivably be true. One might, for example, look upon the practice of science as a diabolical way of blinding one to the charms of virtue. One might look upon the practice of science as a deliberate plot to efface virtue, destroy it. Worse, one might look upon the practice of science as entirely apart from the issues of good and bad, of right and wrong, or of virtue and viciousness. The practice of science may be conceived as blind, itself vicious, or irresponsibly indifferent.

In this paper I attempt to trace certain aspects of the evolution of theories of space-time and mechanics as revealed by a brief comparative study of Newtonian theory, Robb's theory, general relativity, and Milne's kinematical relativity. The first object is to emphasise how each theory leaves us in a position in which the succeeding one appears as a perfectly natural next step in the development of ideas. The second object is to show how, in spite of superficial differences in character, the theories all necessarily possess the same general structure constituted by the presence of hypotheses, from which certain general mathematical relations are deduced, which in their turn are used to predict relations between observable quantities.

As is rather generally admitted today, the terms of our language in scientific as well as in everyday use, are not completely precise, but exhibit a more or less high degree of vagueness. It is the purpose of this paper to examine the consequences of this circumstance for a series of questions which belong to the field of logic. First of all, the meaning and the logical status of the concept of vagueness will be analyzed; then we will try to find out whether logical terms are free from vagueness, and whether vagueness has an influence upon the validity of the customary principles of logic; finally, the possibilities of diminishing the vagueness of scientific concepts by suitable logical devices will be briefly dealt with.

This paper is concerned with two closely related problems: the first is the general question of border-line cases; the second is a suggested identification of the notions of ambiguity and vagueness. In the first part of the paper I propose to discuss border-line cases in the following way: I shall say what is meant by “border-line cases,” discuss their genesis, enumerate and evaluate the different methods of resolving such cases, and make a brief comment or two the bearing, if any, that such cases have on logical theory. In the second part it will be suggested that the notion of vagueness can be reduced to the status of a special but important case of ambiguity; I hold that such a reduction would effect both an economy and a clarification.

Tradition usually assigns greater importance to the so-called laws of thought than to other logical principles. Since these laws could apparently not be deduced from the other principles without circularity and all deductions appeared to make use of them, their priority was considered well established. Generally, it was held that the laws of thought have no proof and need none, that as universal constitutive or transcendental principles they are self-evident.

Professor Reichenbach's writings have repeatedly called attention to the important rôle which probability statements play in all inquiry, and he has made amply clear that no philosophy of science can be regarded as adequate which does not square its accounts with the problems of probable inference. Recently he has brought together in convenient form many reflections on the methodology of science familiar to readers of his earlier works, and at the same time he has set himself the task of solving many well-known problems of epistemology in terms of his theory of probability. His latest book is therefore of great interest, both because of the light it throws on Professor Reichenbach's own views and because it reveals the power and limitations of one approach to the problems of science. In particular, while it does not add to the details of his theory of probability worked out elsewhere, the applications Professor Reichenbach now makes of it supply fresh clues for judging its import and adequacy. The object of the present essay, therefore, is to expound a number of his views on probability and epistemology, with a view to examining his conclusions and their relevance to the problems he aims to resolve. The discussion will try to determine whether several features of his present views do not follow from assumptions which he has not sufficiently considered; whether his logical constructions do not create new puzzles; and whether a different starting-point should not be taken if the clarification of scientific concepts and procedures, to which Professor Reichenbach's devotion is as unexcelled as it is well known, is to be successfully conducted.