Pp. xii, 212 , Cambridge , Polity Press , 2006 , $70.00.

We have here a well-informed, unpretentious, lucid and eminently readable approach to the central subject of philosophy.

Part I introduces the topic, and puts the preliminary question - the answer to which is surprisingly elusive, like so many in philosophy - what is knowledge? What, to move a little farther on, are the sources of knowledge? As a first approximation, perception and testimony seem obvious candidates, while a priori knowledge presents special problems of its own. (For example, as Kant wondered, why are we so sure that every event is caused, since, to say the least, we haven't observed every event, let alone every event being caused? And yet this prejudice, which we seem to bring to our knowing rather than deriving it from it, is one on which the whole of our science, as well as a great deal of our common sense, seems to depend.) The topic of justification is broached in the third part, by way of foundationalism, coherentism, internalism and externalism. The bogey of scepticism which inevitably haunts the theory of knowledge is next under consideration, along with the problem of induction which is so closely bound up with it. After a survey of ‘naturalized epistemology’, the book ends with a consideration of four problematic areas of knowledge, namely memory, other minds, morality (is there moral knowledge or not?), and God.

It is characteristic of sceptics, as we are told, to claim that we don't have as much knowledge as we are apt to think that we have. Some sorts of scepticism are localized – as when someone tells us that we don't have, and can't obtain, knowledge of the past; and some are comparatively general, applying to virtually all of our knowledge-claims. How, if at all, can scepticism, whether local or general, mild or radical, be contested? If our senses sometimes deceive us, as plainly they do, why shouldn't they always do so? As Descartes famously pointed out, dreams, while you are having them, are often indistinguishable from waking life. (It is told of an English peer that he dreamt he was making a speech in the House of Lords, woke up, and found that he was; and the same is alleged of an oboist performing in Handel's Messiah.) Can we wriggle out of it by saying that the experiences of ordinary life have a consistency, congruity and coherence about them which is lacking in dreams? (As G. K. Chesterton remarked, if someone reports a dream about an archangel unfolding a scroll, on which are inscribed the names of all the dead being summoned to judgment, one can be sure that he is lying; in a real dream, the scroll would undoubtedly contain the times of the week-end excursion trains to Brighton.)

It seems natural to say, that we would be in a position to refute scepticism if we had a clear notion of what the foundations of knowledge are. In connection with these alleged foundations, two debates are considered here, that between foundationalists and coherentists, and that between internalists and externalists. The internalist is preoccupied whether the evidence available to me is sufficient to justify the judgments that I make; while the externalist stresses that there are objective criteria for assessing one's epistemic practices, whether one attends to them or not. (I might be ever so confident that I could rely on information gained from the archangel's scroll in planning my week-end; but the degree of my confidence would have no bearing on the reliability of my information.) Perception may seem unproblematic as a foundation of knowledge; but just what is it that we perceive? To say that we directly perceive physical objects in space seems to go beyond what is warranted; our present perceptions could be just the same, but the objects apparently perceived could turn out not to be really there after all. But to say that what we directly perceive are ‘sense-data’ or ‘sense-contents’ appears to commit us to entities which are metaphysically problematic; since these seem to be mental rather than physical, we may find ourselves mired in all the difficulties which are notoriously entailed by a radical dualism.

‘Naturalized epistemology’ has become fashionable, sponsored as it was by the late and very influential W. V. O. Quine. The traditional epistemological approach represented by Descartes and Hume, which sought to provide a justification of our knowledge, has failed, in Quine's view, and cannot be revived. So why not simply give a scientific account of how we come to have the beliefs that we do? As Quine writes, ‘(t)he stimulation of his sensory receptors is all the evidence anybody has to go on, ultimately, in arriving at his picture of the world. Why not just see how this construction really proceeds? Why not settle for psychology?’ (p. 127). The answer is the obvious one, that psychology, so long as it sticks to its last, can only inform us of why we happen to hold the beliefs that we do; and cannot answer the question of which of these beliefs are apt to be true of the world, and why, which is the proper business of epistemology. For all Quine's prolific brilliance, he never gives a plausible justification of his view that this question can be properly brushed aside.

The questions posed for the pupil at the end of each chapter are excellent, and some have the authentic philosophical zaniness about them. ‘1. In order to know that there is a book in your hand, do you need to know that you are not a brain in a vat? 2. Could the demon or the evil scientist trick us into falsely thinking that 2+2=5 or that there may be a bachelor who is married?’ (p. 114).

One thing about this book, and many others on related subjects, does bewilder me. How is it that a very good book on epistemology, as this one undoubtedly is, can neither mention nor take account of the writer whom I, and not a few others, regard as the greatest epistemologist of the last century, Bernard Lonergan? Is this another consequence of the tribalism that has been so striking a feature of the philosophy of the last sixty years or so, and which one had hoped was at last letting up a little?