Why the ‘by and large’ above? The reason is that sometimes we do discover what we ourselves believe by making inferences from our own behaviour. A retired university dean, in the course of writing his autobiography, may notice a pattern in his appointment and promotion decisions that reveals to him that he is biased against women. He may be shocked and surprised by this discovery; he has always believed that he believes that women are the intellectual equals of men. Examples like these tell us that sometimes we discover what we ourselves believe by observing and making inferences from our behaviour, and also that our beliefs about what we ourselves believe can be mistaken. The same goes for our desires. Sometimes we make discoveries about what we desire by noticing what we do. Someone who affirms that she likes camping but somehow or other always finds an excuse not to go camping may come to acknowledge the fact that she doesn’t like camping.

All the same, examples like these should not blind us to the fact that mostly our beliefs about our own beliefs and desires don’t come from observing our own behaviour, and the same goes for our beliefs about a great many of our own mental states. My belief that I am not now in pain, and my belief that I am having a visual experience as of trees moving in the wind, were not arrived at by my looking at my body. Each of us has a way of finding out about a good number of our own mental states that does not rely on our observing our own behaviour, or indeed anyone else’s behaviour. We are able – as philosophers, psychologists, and cognitive scientists typically express it – to acquire beliefs about our own mental states by introspection. This fine collection of fifteen essays – edited by Daniel Stoljar (ANU) and Declan Smithies (Ohio State University) – is about the nature of introspection (and how it connects with what makes us conscious; more on this anon).

The essays cover pretty much the whole range of the possible (out of the at all sensible) views about the nature of introspection. Here is a snapshot, to give a sense of the territory covered.

(i) Introspection is, as the name suggests, a kind of inner sense. It is like sight and sound, except that it is directed internally. Supporters of the view that mental states are brain states often articulate a position of this kind in terms of the brain carrying out a kind of self-monitoring or self-scanning process: a belief about some given mental state, M, is a brain state whose job it is to monitor another brain state, namely, the brain state that is M itself.

(ii) It is misleading to use a single term, ‘introspection’, for our access to our own mental states. Our mode of access differs from one kind of mental state to another, and varies depending on circumstances. It isn’t the product of a single faculty.

(iii) Mental states, or at least a good number of them, are special in the following sense: one’s being in them, in and of itself, provides justification for believing that one is in them. When I believe that the trees in front of me are moving in the wind, the fact that they are does not, in itself, provide a justification for my belief. I must, for example, see or hear the trees moving. But in the case of some mental states, one’s being in them can provide a justification for believing that one is in them, all by itself. Nothing extra is called for. Saying that these mental states are able to be accessed by introspection is simply a way of saying this.

(iv) Introspection isn’t directed at one’s mental states as such; it is instead directed at their contents. When one asks oneself what one believes, introspection reveals the content – what one believes – not the fact of belief as such. This is why asking oneself the question ‘Do I believe that the Coalition will win the next election?’ seems awfully like asking oneself the question ‘Will the Coalition win the next election?’ Of course, anyone who likes this approach has to give an account of how someone comes, say, to believe that she believes that the Coalition will win, as opposed to believing that she desires that the Coalition will win. Because the belief and the desire have the very same content, if it is true that introspection is directed to content alone, it won’t by itself tell a subject whether she believes or desires that the Coalition will win.

(v) Introspection cannot be understood independently of consciousness. The explanation of how it is possible to have special access to our own mental states lies in the fact that we are able to be conscious of them. When I introspect my current mental states, I become conscious of them, and that gives me a special way to form beliefs about them, a way I don’t have for the mental states of the man sitting on the other side of the room. This proposal can be combined with the inner-sense view we mentioned earlier. It is, it might be held, the operation of one’s inner sense that makes one’s mental states conscious: mental states become conscious by being introspected. A view of this kind needs, of course, to be supplemented by an account of consciousness that explains how it can be a source of justification.

Finally, any account of introspection has to respond to the fact that the phenomenon we are talking about – the first person–third person asymmetry – isn’t confined to beliefs about mental states (and, speaking for myself, I think this point deserves more attention than it usually receives). My belief about whether or not my legs are crossed typically has a very different source from my belief about whether or not the legs of the man sitting on the other side of the room are crossed. True, I can see that my legs are crossed, but normally I don’t need to in order to justifiably believe that they are. I do, however, need to see the legs of the man sitting on the other side of the room in order to arrive at a justified belief about whether or not his legs are crossed.

Anyone interested in these issues should read this volume. But be warned; although the writing is of a high standard and refreshingly free from unnecessary jargon, the book is demanding. The editors have, though, been kind to us. The introduction is outstanding.