He begins with the curious case of color in dreams. When people today are asked whether they regularly dream in color, most say they do. But it was not always so. Back in the 1950s most said they dreamed in black and white. Presumably it can hardly be true that our grandparents had different brains that systematically left out the color we put in today. So this must be a matter of interpretation. Yet why such freedom about assigning color? Well, try this for an answer. Suppose that, not knowing quite what dreams are like, we tend to assume they must be like photographs or movies — pictures in the head. Then, when asked whether we dream in color we reach for the most readily available pictorial analogy. Understandably, 60 years ago this might have been black-and-white movies, while for most of us today it is the color version. But, here’s the thing: Neither analogy is necessarily the “right” one. Dreams don’t have to be pictures of any kind at all. They could be simply thoughts — and thoughts, even thoughts about color, are neither colored nor non-colored in themselves.

This explanation is of a piece with Schwitzgebel’s general line. We are fantasists about our own mental experiences because we have little other choice. When we are probed by questions beyond our introspective competence, we have to make the answers up as best we can. Schwitz­gebel’s message is very much in keeping with much writing in contemporary psychology that aims to knock us from our pedestals of Delphic self-assurance: to prove that we are, as Timothy Wilson says, “strangers to ourselves.”

This could all be true. We often do have trouble telling what’s going on inside our minds. But still I can’t say this is always because of feeble introspection. I suspect the real problem may be not that we know too little about our mental states but that we know too much. We are asked to say “what it’s like” — to dream, to imagine, to feel — as if there ought to be a simple answer: colored or not, single or double, in the head or in the heart. But, when it comes to it, the rich totality of our experience will not fit the Procrustean bed that philosophy, and everyday discourse also, tries to impose on it.

In the 1780s, Thomas Reid, a leading figure of the Scottish Enlightenment, chided his colleagues on just this score: for not appreciating the complex multilayered character of sensory experience. Reid argued that there are always two parallel threads to our experience: “The external senses have a double province; to make us feel, and to make us perceive.” Sensation is how we represent sensory stimuli at the surface of our bodies — the mental representation of “what’s happening to me”; perception, by contrast, is how we represent the outside world, “what’s happening out there.” And these two processes have dissimilar characteristics: sensation is raw and immediate, perception more categorical and slow.

Question, then (it’s one of Schwitzgebel’s examples): When the lights go up on a complex scene, do we immediately “see” the whole scene? The answer can only be yes, and no. At the level of visual sensation, yes, it’s all there, every part of the field, every stitch of the tapestry, seems to be filled in at once. But at the level of perception, no, our picture of what’s out there in the world gets built up over seconds. “What exactly is my experience?” If exactly means simply, this question is one to which there’s no good answer.