In this article, three descriptive models are described and compared in an attempt to discover the minimum number of concepts and relations necessary to an abstract description of social structure. It is argued that a “situational model” which uses the concepts of social time, social space and social role together with the relations of internal structure and external distribution is both adequate to the task and superior to the two other models. The advantages and implications of the situational model are discussed.

In both axiomatic theories and the practice of extensive measurement, it is assumed that a series of replicas of any given object can be found. The replicas give rise to a standard series, the “multiples” of the given object. The numerical value assigned to any object is determined, approximately, by comparisons with members of a suitable standard series.

This prescription introduces unspecified errors, if the comparison process is somewhat insensitive, so that “replicas” are not really equivalent. In this paper, it is assumed that the comparison process leads only to a semiorder, which allows for such insensitivity. It is shown that, nevertheless, extensive measurement can be carried out, provided that a certain set of (plausible) axioms is valid. Approximate measures, and their limits of error, can be derived from finite sets of semiorder observations. These approximate measures converge to ratio-scale exact measurement.

In his article “Explanation Sketches” [3], Fred Newman argues that Scriven is mistaken in his interpretation of Hempel's notion of explanation sketch. According to Scriven, to complete an explanation is to fill in further initial conditions so that the explanandum of the sketch would be entailed by the new enlarged set of initial conditions. The point may be alternatively put by saying that according to Scriven to have a complete explanation is to have a covering-law which connects initial conditions with the explanandum of the original sketch. Now Scriven's point against the deductive theory as applied to History is just that very often when we try to complete a given explanation sketch, we only succeed in unearthing a law which is either false or else trivial. Newman, however, contends that this is an excusable but, nevertheless, unsympathetic way of interpreting Hempel. He suggests an alternative account to the effect that to complete an explanation we need not necessarily produce a covering-law connecting initial conditions with the explanandum; all we need to do is to mention other initial conditions and certain laws which need not necessarily contain mention of the explanandum of the sketch. As he himself puts the point: “However, generously interpreted, when Hempel speaks of a sketch vaguely indicating laws we may take him as merely suggesting that some laws are vaguely indicated which would make up the explanans of an explanation of the event in question—not necessarily in the terms which describe the event in the sketch's explanandum.” ([3], p. 170).

The paper has two main aims. The first is to reformulate Hempel's version of the thesis of the symmetry of explanation and prediction, as regards the deductive covering-law model, so as to generalise it and make it no longer subject to some of the criticisms which have been directed at it (Section II). The second aim is to consider, with special critical reference to Hempel's recent treatment in Aspects of Scientific Explanation (New York and London, 1965), some central criticisms of both the constituent parts of the above symmetry thesis, viz. that adequate explanations are potentially predictive (Section III), and that adequate predictive arguments are potentially explanatory (Section IV).

T. S. Kuhn's book, The Structure of Scientific Revolutions, [1], is a long and complex work, containing a large number of examples and arguments bearing on questions in the philosophy, history, and sociology of science. My treatment of it here will necessarily be limited, but I will try to state its main theses and discuss them insofar as this can be done without detailed examination of the examples cited from the history of science.

Anyone, today, with even a slight interest in the methodology of science will be aware of the heated debate which has raged in regard to the thesis of the logical symmetry between explanation and prediction, which is entailed by the hypotheticodeductive account of scientific theory. The symmetry thesis, which received its classical exposition in a well-known article by Hempel and Oppenheim [2], has been subject to a steadily growing criticism by several eminent thinkers. My intention, in this article, is to argue that the current reaction to the Hempel-Oppenheim position, as exemplified by Professors Hanson, Scriven, et al., represents a retrograde movement in the philosophy of science, which, as the number of its converts grows, could undermine the progress, which has been accomplished in the broad tradition that extends from Mach and Poincaré through the Vienna Circle to the present day. Specifically, it is my contention that the aforementioned reaction is symptomatic of a contemporary trend in the direction of irrationalism which, of all branches of philosophy, the philosophy of science should seek to dispel rather than to foster. For the sake of brevity, I propose to focus my remarks wholly on the original widely read article of Hanson on this subject [1]. That I single out this particular source should not be taken to belie the admiration I hold for the masterful scholarship of its author.

Professor Marcucci's book on Whewell [6] is a comprehensive expository treatment of Whewell's philosophy of science. The work contains chapters on Whewell's theory of ideas, the fundamental principles of his philosophy of science, his views on mathematics and mechanics, and on his philosophy of induction and philosophy of discovery. In addition there is a chapter on the English reception of Whewell's thought. Professor Marcucci's notes are rich, both in references to Whewell's many critics and to nearly all of the extant literature on Whewell. Indeed, no full study of Whewell has as yet appeared that makes better or more extensive use of all the relevant literature on Whewell.

It is widely agreed that ‘scientific law’ (or ‘law of nature’) is one of the key scientific terms which any adequate philosophy of science must attempt to clarify or define. The importance of the concept ‘law’ is made evident by the fact that the distinctive functions of science—explanation and prediction—are usually analyzed with reference to laws. Thus events are explained by showing that descriptions of them are deducible from laws (conjoined with suitable statements of “initial conditions”), and laws are utilized in deducing descriptions of unknown future events, thereby permitting their prediction. Moreover, it has recently become clear that the concept ‘law’ is relevant to the analysis of counterfactual conditionals, disposition terms, and the physical modalities. An adequate explication of ‘law’, then, will further the analysis of these important concepts.

Reanimated for the contemporary literature in the writings of Quine ([15]), [16]) and Kuhn [7], the conventionalism of Duhem [2] and Poincaré [12] has emerged in the last few years as one of the genuinely interesting topics in the philosophy of science. The theory in question—let us follow Grünbaum [3] in calling it the D-thesis, after its founder, Pierre Duhem—claims three things: (1) a single scientific hypothesis H is never disconfirmable in isolation from its fellow; (2) every single hypothesis H of science presupposes, explicitly or implicitly, the support of a conjunction A = A, • A2 • … • Am of auxiliary assumptions or hypotheses; (3) the failure of an observational consequence of H in face of contradictory evidence disconfirms only the conjunction of H and A, not H alone—i.e. establishes only ∼ (H • A). The logical picture is as follows:

Permit me to reply to the recent note [1] in this journal by Robert J. Ackermann, concerning my critical comments (in [4]) on Nelson Goodman's entrenchment theory.

In Howard Kahane's current reply to my previous discussion of Goodman's elimination rules, he suggests both that the notion of conflict required by the first elimination rule cannot be made clear, and that both proposed revisions of the second elimination rule are too strong [4]. These seem to me to be the points which require settlement, and I would like to discuss them in this paper.