Pp. x, 154 , Princeton University Press , 2008 , $29.95.

Forster's aims in the first part of Kant and Scepticism are to clarify what kind of skepticism motivates and concerns Kant (in the Critique of Pure Reason) and outline how Kant deals with such skepticism. Forster argues that Kant is concerned with those varieties of skepticism that threaten metaphysics – Humean and Pyrrhonian skepticism. Hence Kant's two well known aims in the Critique – to address skepticism and develop a reformed metaphysics – belong together (p. 3). I'll remark mainly on Forster's discussion of Pyrrhonian skepticism.

In Chapter 4 Forster notes that for Kant Pyrrhonian skepticism has two essential features: first ‘a setting of [some] claim against a contrary claim and demonstration that equally strong arguments could be given on both sides’ (the equipollence method), or as Kant puts it, ‘different but equally persuasive metaphysical propositions [i.e. propositions regarding supersensuous reality] lead inescapably to contrary conclusions’ (pp. 17–18). Second, and a result of the first, a ‘suspension of judgement about the issues in question’ (ibid).

In Chapter 6 Forster discusses Kant's ‘reformed metaphysics’ and how it is designed to forestall skepticism. Such a metaphysics is at its core a metaphysics of nature that ‘bears a strong resemblance … to traditional general metaphysics …’ (p. 35). This metaphysics does not countenance the supersensuous realm that is susceptible to the Pyrrhonian attack.

The general concepts and principles the reformed metaphysics involve are those such as cause and every event has a cause, concepts and principles that the Humean skeptic will worry about. Kant's reformed metaphysics, however, involves an anti-skeptical strategy designed to forestall worries about the reference of such concepts, and the truth of such principles. Kant attempts to prove that such concepts/principles refer/are true. To establish the conclusions of such proofs Kant uses transcendental arguments which show that the reference or truth in question is a condition of the possibility of experience of a certain type. Hence, given that there is experience of the relevant type (something Kant takes to be unquestionable, even by the skeptic's lights) the anti-skeptical conclusion follows.

The above is a snippet of the kind of anti-skepticism Forster finds in Kant. In the second part of Kant and Skepticism Forster subjects Kant's position to severe criticism.

For Kant the Pyrrhonist's attack takes only (supersensuous) metaphysics within its scope and doesn't ‘challenge [the assumption] that one has experience of certain types …’ (p. 76), an assumption that is pivotal for Kant's reformed metaphysics. But Kant's interpretation of Pyrrhonism as a moderate skepticism is questionable; as Hegel argued, Pyrrhonism in fact attacks all beliefs.

Still, might Kant be entitled to discount the more radical Pyrrhonism? One can take Kant, Forster notes, to hold that no plausible skeptical attack is even possible. But why might Kant think that? Forster thinks it's because he holds a version of the Cartesian doctrine that ‘a person's current subjective experience necessitates his acknowledgement (or belief or knowledge) of it, so that he cannot question it’ (p. 80). Kant's version of the doctrine has significant modifications (pp. 81–82) one of which is that for Kant one must have, of necessity, only the ability to acknowledge one's current subjective experience.

However Forster argues, on various grounds – and to my mind convincingly – that this doctrine does not provide a decent argument for the impossibility of radical Pyrrhonian doubts (Chapter 12). A consequence of this, Forster suggests, is that ‘Kant's strategy of answering skepticism concerning metaphysics by means of transcendental arguments which presuppose that we have experience of certain types … [seems] objectionable’ (p. 82).

I don't think that Forster is entitled to draw the latter consequence. For Kant's project to be objectionable by Pyrrhonian lights, we need not only the possibility or actuality of the equipollence method being used against judgements of subjective experiences, but also the conclusion that the application of the method is well motivated. Forster hasn't given us that, nor, I take it, has he tried to. Showing that skepticism is possible or actual is one thing; showing that one is rationally required to reckon with it is another.

Not only does Forster argue that Kant's case for the impossibility of radical skeptical doubts is flawed, he seems to think that such doubts are possible, since against Kant he notes that there are philosophers who deny the reality of subjective experience – and ‘if serious denials are possible, it is surely hard to believe that serious doubt is not’ (p. 81). However, there can be such a thing as the illusion of doubt. One might be sincere in denying that p, yet fail to satisfy conditions for genuine doubt that p (cf. Wittgenstein's On Certainty).

The message of Forster's book is an anti-dogmatism that is presented in a Pyrrhonian and Hegelian spirit. One can view the rich discussion and criticism of Kant as a way of getting this message across. The message is persuasive and ingeniously conveyed in an enjoyable and refreshing book. I recommend Kant and Skepticism to Kant scholars, those interested in skepticism, and those interested in Hegel's criticisms of Kant.