Williamson on Knowledge, by Patrick Greenough and Duncan Pritchard (eds). Oxford and New York: Oxford University Press, 2009. Pp. ix+400. £60.00. According to Timothy Williamson's knowledge-first epistemology––mainly presented and articulated in Williamson's ground-breaking and controversial Knowledge and its Limits (OUP, 2000)––the notion of knowledge is primary and unanalysable, and other central epistemological notions––such as that of belief, evidence and epistemic justification––are to be analysed in terms of their relationships to the notion of knowledge. According to knowledge-first epistemology knowing is a non-luminous (i.e. non-necessarily transparent to the subject) purely mental state (i.e. not conjoint with any non-mental condition). On this view knowing can be characterised as the most general factive mental state. The volume Williamson on Knowledge aims at a critical assessment of knowledge-first epistemology. It includes fifteen contributions signed by some of the most interesting philosophers active today, some established and others up and coming. Each contribution is commented on––often quite thoroughly––by Timothy Williamson himself. The contributions are preceded by a short introduction by the editors. This volume is not an introduction to Williamson's epistemology. It rather has the structure and the aims of a comprehensive book symposium that adds to and completes earlier minor symposia dedicated to Knowledge and its Limits (see for instance Analytic Philosophy 2004, 45, 5 and Philosophy and Phenomenological Research 2005, 70, 2). The volume appears suitable for an audience of (mainly postgraduate) students and scholars of philosophy who are already familiar with Williamson's knowledge-first epistemology but look for clarifications, further explanations, or aim at a critical assessment of it in the light of more recent philosophical reflection. The book turns out to be a very valuable tool with respect to these aims: it gives us a clear picture of which aspects of knowledge-first epistemology appear more problematic, and why they appear so, in the context 2 of present-day epistemology and philosophy of mind. Williamson's responses to his critics–– whether persuasive or not––are effective in clearing up confusions and misinterpretations of his views. In his comments Williamson returns to some of the most controversial arguments and claims made in Knowledge and its Limits. He recasts them, adds further details and explanations, and clarifies connections and consequences left implicit before. The upshot is often illuminating. Those who have a special interest in Williamson's first-knowledge epistemology should definitely read this book. Williamson on Knowledge would have benefited from a longer and more articulated introduction. The editors do a nice job in summarising the interrelated theses and principles that constitute the core of knowledge-first epistemology, but they give no presentation of the contributions to their volume. These fifteen articles naturally gather into a few related clusters depending on which theses or principles of Williamson's epistemology they primarily target. A map of these clusters would have helped the reader find her own pathway through this bulky volume. Here is a basic map: the thesis that the notion of knowledge cannot be reduced to more basic concepts is mainly criticised in the contributions by Quassim Cassam and Ram Neta. The claim that knowing is a purely mental state is principally criticised in the contributions by Elisabeth Fricker, Frank Jackson and Ernst Sosa. The claim that mental states are not luminous is criticised by Ernst Sosa, and more specifically by Matthias Steup and Neil Tennant. The thesis that one's total evidence coincides with one's total knowledge is criticised by Tony Brueckner, Alvin Goldman, Jonathan Kvanvig and Ram Neta. The thesis that knowledge is the norm of assertion (assert p only if you know that p) is questioned by Stanford Goldberg and Jonathan Kvanvig. Furthermore Alvin Goldman, John Hawthorne and Maria Lasonen-Aarnio (the last two have a joined contribution) and Ernst Sosa criticise knowledge-first epistemology by focussing on the externalist features (mainly the satisfaction of a safety condition) that Williamson ascribes to knowledge. Mark Kaplan challenges Williamson's conception of evidential probability. Tony Brueckner, Alvin Goldman and, 3 more specifically, Stephen Schiffer question Williamson's asserted antisceptical consequences of knowledge-first epistemology. Finally Charles Travis challenges Williamson's defence of bivalence (which is not strictly speaking an essential component of knowledge-first epistemology though––as Williamson explains in his comment––it's relevant to it). Some of the contributors directly attack Williamson by arguing that key theses of his epistemology are flawed; others claim that some of his views are not sufficiently supported or contend that they don't fare any better than more or less established rivals. Some critics also suggest variants or even possible improvements of knowledge-first epistemology. As one would expect, there is no dramatic turn in Williamson's views: he doesn't take on any of the points made, though he concedes that some of the issues under discussion would need a more thorough investigation. The reader might feel frustrated when––occasionally––Williamson quickly dismisses long and sophisticated arguments by adducing the reason that they rest on misinterpretations of his views. It is hard to judge whether Williamson is always fair in these cases. Even so the reader would do better to take a look at Williamson's comments before immersing herself in the study of a contribution or a demanding part of it. Let us now put some meat on these bones by considering some of the criticisms made against knowledge-first epistemology and Williamson's responses. Cassam (pp. 22-25) voices an objection that appears important at the very least because it must have crossed the mind of several readers of Knowledge and its Limits. Though Williamson insists that the notion of knowledge cannot be reduced to more basic concepts, Williamson's practice in Knowledge and its Limits looks just like reductive conceptual analysis. For if on the one hand Williamson explains or characterises the verb 'know' as the most general factive mental state operator (FMSO) (where less general FMSOs are for example 'see' and 'remember'), on the other he explains the concept of an FMSO without using the concept of knowledge. Thus it seems that the notion of an FMSO is more explanatorily basic 4 than the notion of knowledge. Doesn't this show that Williamson's explanation of the concept of knowledge in terms of the concept of an FMSO is reductive after all? Williamson's defence (pp. 285-287) distinguishes between two senses of 'explanation'. A working explanation of a concept is one that says enough to enable someone to become linguistically competent for the first time with an expression for that concept––it comes in terms of examples or a rough verbal definition. A theorising explanation is, on the other hand, one that presents a definite theory about the underlying nature of a concept or its role in a wider setting. Williamson clarifies that his explanation of the concept of an FMSO that doesn't use the concept of knowledge is just a working explanation, and that it is also possible to give a working explanation of the notion of knowledge without using the notion of an FMSO. Thus in the working sense, neither the concept of an FMSO nor the concept of knowledge is explanatorily more basic than the other. Williamson also contends that in the theorising sense one cannot give a sufficiently good explanation of the notion of knowledge without using the notion of an FMSO, and vice versa. Thus also in the theorising sense, neither the concept is explanatorily more basic than the other. Perhaps Williamson should supply a few independent examples and further details, but this response will strike many readers as prima facie plausible and illuminating. Other objections would seem to give Williamson a more hard time. A thesis of knowledge-first epistemology that emerges as one of the most problematic in this volume––judged by the number of objections received––is that which states that one's total evidence coincides with one's total knowledge; concisely E = K. The critics of E = K contend that this view appears unjustified or even intuitively false in many cases. Let us dwell with two of these objections. Suppose p = 'this cup is red' and that I have the experience as if p so that I'm perceptually justified in believing that p. Also suppose that my experience is veridical. Rigorously speaking I'm justified in believing that p in virtue of my total evidence. Thus, given E = K, I'm justified in believing that p in virtue of my total knowledge. Since my experience as if p is veridical, I know 5 that p. Thus I'm justified in believing that p in virtue of my total knowledge and specifically because my total knowledge includes my knowledge that p. In conclusion, Williamson's explanation of why I'm perceptually justified in believing that this cup is red, when I actually know it, says that I'm so because I know that this cup is red (cf. p. 208). According to Brueckner (pp. 8-10) this explanation is flawed because we can meaningfully ask: what is the evidence that enables me to know that p by justifying me in believing that p? And it is clear that if E = K is accepted this question has no answer. So E = K must be false. In the imagined situation my best evidence for my knowledge that p is my evidence that p––i.e. my knowing that p. But it appears meaningless or very odd to say that the evidence that enables me to know that p is my very knowing that p. Brueckner's objection seems to be driven by the deep-rooted conviction that if I perceptually know that p and, thus, I am perceptually justified in believing that p, I must possess some sensory data that enable me to have that knowledge and justification. Williamson's reply is as expected: 'Brueckner fails to make sense of my view because his discussion is imbued throughout with the traditional assumptions that I am denying' (p. 282). Williamson insists that even if I know that p directly by perception, I have no evidence that enables me to know that p, for having evidence that p and knowing that p is one and the same thing. But Brueckner might score points here. Explaining how sensory data rationally affect our beliefs to produce knowledge and justification is admittedly one of the most tormented problems in philosophy. The fact that knowledge-first epistemology circumvents this problem must have appeared to be one of its strengths at first. Yet today––more than ten years after the publication of Knowledge and its Limits––we should perhaps question that initial impression, for there is a seemingly promising answer to the problem of perceptual evidence. The view that apparent perceptions have propositional or representational content looks increasingly believable and it is largely accepted in today's philosophy of mind and epistemology. If apparent perceptions have contents, they may be capable of supplying reasons for our beliefs––they may constitute those data 6 that enable us to have perceptual knowledge and justification. (On this topic see Susan Siegel and Nicholas Silins, 'The epistemology of perception' in Mohan Matthen, ed., The Oxford Handbook on the Philosophy of Perception, forthcoming, OUP). Note that it is very implausible that apparent perceiving is a case of knowing. For apparent perceiving is not factive: I can apparently perceive that p even if p is false. Thus this pervasive conception of perception entails that perceptual evidence is not knowledge, which is incompatible with E = K. Goldman (pp. 85-90) raises independent difficulties to E = K. He proposes an alternative construal according to which: (E = NPJ) P is an item of evidence for a subject S at time t =def P is non-inferentially, propositionally justified for S at t. Suppose for instance S has the visual experience as if there is an apple before her at t. Goldman suggests that the mere fact that S is in this visual state can make S (prima facie) justified in believing the proposition P = 'There is an apple before me' at t whether or not S believes P at t. Since P is non-inferentially, propositionally justified for S at t, P turns out to be an item of S's evidence at t on E = NPJ. Goldman argues through examples that E = NPJ is capable of explaining all that E = K explains and additional things. He concludes that E = NPJ is rationally preferable to E = K. Williamson's response (pp. 308-312) systematically questions Goldman's examples and arguments. As always Williamson's observations are subtle and interesting, but I doubt that many readers will be persuaded. There is an elementary reason why E = NPJ looks prima facie more plausible than E = K. E = NPJ can straightforwardly account for very basic platitudes such as the commonplace view that S can have misleading evidence (P can be evidence for S on E = NPJ even if P is false) or overlooked evidence (P can be evidence for S on E = NPJ even if S doesn't believe P). In contrast E = K cannot easily account for these basic platitudes. For since knowledge entails truth and belief, any piece of evidence that S possesses, on E = K, must be true and believed by S. 7 I have been able to survey only a very few of the numerous and stimulating criticisms of knowledge-first epistemology that the reader can find in Williamson on Knowledge. Williamson's ground-breaking epistemological position might appear prima facie plausible because of the discouraging list of failed attempts to provide a reductive analysis of knowledge. Yet its real strength depends on the number of coherent and mutually supporting theses that follow from Williamson's central assumption that knowledge is basic and unanalysable. The appropriate method of appraisal of knowledge-first epistemology can only consist in the assessment of many or most of these consequences at once. The essays in Williamson on Knowledge jointly attempt at such an overall evaluation. This is why this volume turns out to be so intriguing and valuable. Department of Philosophy LUCA MORETTI University of Aberdeen Old Brewery, High St Aberdeen, AB24 3UB Scotland, UK