This paper presents a critical examination of claims advanced by several philosophers to the effect that ‘time travel’ represents a physical possibility and that the interpretation of certain actually observed phenomena in terms of ‘time travel’ is both legitimate and advantageous. It is argued that (a) no convincing motivation for the introduction of the time travel hypothesis has been presented; (b) no coherent and interesting sense of ‘going backward in time’ has been supplied which makes ‘time travel’ compatible with Special Relativity; (c) even the conceptual possibility of ‘time travel’ is an unsettled and somewhat nebulous question.

The following intellectual as opposed to practical reasons for all anthropologists doing fieldwork are examined: fieldwork: (1) records dying societies, (2) corrects ethnocentric bias, (3) helps put customs in their true context, (4) helps get the “feel” of a place, (5) helps to get to understand a society from the inside, (6) enables appreciation of what translating one culture into terms of another involves, (7) makes one a changed man, (8) provides the observational, factual basis for generalizations. None of these is found sufficient to make fieldwork imperative for all anthropologists, although they are quite sufficient to allow that it is imperative for anthropology as a whole that fieldwork in some form by some people continue. In place of the view of fieldwork as an essential preparation for doing anthropology, an alternative role for it is explored: namely as a testing procedure. The implications of this—that the study of problems and the articulation of theories can usefully proceed prior to or even independently of fieldwork—are drawn out, and a new institution of selective fieldwork is proposed.

The axiom of comparability has been a fundamental part of mathematical choice theory from its beginnings. This axiom was a natural first assumption for a theory of choice originally constructed to explain decision making where other assumptions such as continuous divisibility of choice spaces could legitimately also be made. Once the generality of application of formal choice theory becomes apparent, it also becomes apparent that both continuity assumptions and the axiom of comparability may be unduly restrictive and lead to the neglect of decision situations which are important and which can be handled on a modified axiom set. These considerations bear on the philosophical analysis of the concept of rational decision.

Philosophers who hold that the correct ontological analysis of things includes both properties and particulars have often been pressed to “show” the particular. If we are not acquainted with them, it is argued, then we should not suppose that they exist. I argue that, while we do have good and sufficient reasons for supposing there to be particulars, we are not acquainted with them. To suppose that we are acquainted with them is to treat particulars as if they were properties and to fail to realize how radically different particulars are from properties. The relevance of these matters to some considerations of “simplicity” and the principles of empiricism is explored.

Philosophers have long believed that if the Principle of the Identity of Indiscernibles were logically true, there would be no problem of individuation. I show (a) that if spatial relations are, as seems plausible, of such a nature that it makes no sense to say of one thing that it is related to itself, then the Principle is a logical truth, asserting that a certain kind of state of affairs is impossible because the kind of sentence purporting to express it is ill-formed and (b) that even if the Principle were such a truth the problem of individuation would remain. I then examine some of what Leibniz and Wittgenstein have said about the notions of individuation, difference and non-identity.

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).

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.