In Reason, Truth, and History, Hilary Putnam addresses the notion that we might all be brains in a vat in a way that has been widely discussed.1 What follows is an attempt to get dear on Putnam's argument, more particularly, to determine how exactly that argument goes and what precisely it is supposed to establish. Putnam's presentation is not unambiguous on either count, nor is it always as dear as one might have wished.

In ‘Rationality and Revolution’ Nancy Holmstrom addresses an issue that has gained considerable currency among social and political theorists. She asks what insight, if any, Marxists might glean from rational choice accounts of radical working class collective action. The purpose of this comment is to argue that Holmstrom’s unfavorable estimation of rational choice accounts is ill-conceived.

Holmstrom raises two basic objections to rational choice explanations of working class collective action. First, she contends that such accounts are limited, inadequate or incomplete and indicates several manifestations of this purported deficiency. Second, Holmstrom alleges that rational choice accounts are ideologically suspect and, as such, fundamentally at odds with Marxist explanations of revolutionary action. Holmstrom appears to believe that this second line of criticism ‘follows’ (309, 318) in some sense upon the first. H so, it would be sufficient to establish the error of her initial line of argument. Because neither of her criticisms can withstand scrutiny, however, independent reasons will be advanced for rejecting each.

I consider the contrast between Leibniz's relational concept of spacetime and Einstein's special and general theories of relativity. I suggest that there are two interpretations of Leibniz's view, which I call L1 and L2. L1 amounts to saying that there is no real inertial structure to spacetime, whereas in general relativity the inertial structure is dynamical or real in Lande's sense (see Popper, 46); i.e., it can be ‘kicked’ and ‘kicks back,’ causing gravitational effects. If there is no real inertial structure to space-time then, as Weyl points out (Weyl, 105), the concept of the relative motive of several bodies has no more foundation than the concept of absolute motion for a single body. Thus, L1 seems to be untenable. L2 is a more sophisticated view which rejects the geometrical aspect of Newtonian space-time as a container for events, but accepts the existence of a real structure which determines the inertial properties of matter.

In a recent paper, Peter March proposes to sort out the traditional sorites paradox by distinguishing two senses of ‘resemble.’ The paradox is generated in this way: we have the inference

• (a) A is the same colour as B

• (b) B is the same colour as C

Hence,

• (c) A is the same colour as C

while also having

• (d) A is not the same colour as C

In a recent article in this journal, Roberts (1984) suggests a semantic method for distinguishing ambiguity and generality, a method which is intended to avoid the problems that others such as Zwicky and Sadock (1975), Hintikka (1973), and McCawley (1980) have found in making such a decision. Roberts claims that his test derives its validity from the observation that an ambiguous expression has a disjunction of meanings, whereas a general expression has but one meaning (which might be disjunctive).

In the Critique of Pure Reason, Kant refers often and with no apparent hesitation or sense of ambiguity to the mind (das Gemüt). He does so not only in his justly famous destruction of rationalist proofs of immaterialism, but throughout his own, positive, ‘transcendental’ account in the Transcendental Aesthetic and Transcendental Analytic. In the first edition of the Critique, he even proposed what he adventurously called a ‘transcendental psychology’ and, although this strange discipline seemed to disappear in the second edition, he left in that edition all his frequent references to forms ‘lying in the mind,’ and to the mind, or the self, or the subject of experience, or the ego, doing this or that. Curiously, though, despite an extensive secondary literature, there is in that literature relatively little discussion of what these expressions, in a proper, strictly Kantian sense, are supposed to refer to. There are two imaginative, extremely suggestive articles by Sellars, some hints at connections with eighteenth century psychology offered by Weldon, a tenebrous book by Heidemann, and some recent attention to the general issue of ‘Kant's theory of mind’ by Ameriks and Kitcher.

Arnold Zwicky and Jerrold Sadock (1987) object to my test for distinguishing ambiguity from generality (unspecifiedness) by offering a counterexample and general criticisms about the use of intuitions in the test. Though I disagree with their criticisms, their paper has helped me to become aware of the unclarity of my earlier paper in regard to generality.