This book presents an excellent overview of its subject, accessible to beginners who are willing to work (as reading any serious philosophical book usually requires work) but deep enough to be interesting also to the reader who already knows something about the subject. The story begins with Descartes' reflections on knowledge, certainty, and "I think, therefore I exist"; it moves on through early modern theories of dualism and materialism to contemporary discussions regarding qualia (subjective experiences, such as those of smells and colors, pains and pleasures), consciousness, thought (reasoning), and intentionality (the characteristic feature of mental acts of referring to or being directed towards something, as, for example, my thought that Socrates is a man refers to Socrates). The last chapter, "Persons," presents the Aristotelian/Thomist theory of hylomorphic dualism, in which the soul is the form of the body, rather than (as in Cartesian dualism) a substance completely distinct from matter.
I decided to read this book as a refresher and updater; it is my first serious reading in philosophy of mind since about 35 years ago. After that, I abandoned my philosophical roots to work in artificial intelligence and computer science.
The discussion of contemporary theories reminds me of much that I used to know in the 1970s and brings me reasonably up to date, to about 2006.
My main impression from the book is that philosophy of mind is even stranger and weirder than I remembered it from those days. The treatment of dualism and materialism seems mostly balanced and fair. When it comes to computational theories of intelligence, I am not sure that Feser's exposition expresses an adequate understanding of rule-based computations, or the nature of computation in general; on the other hand, I got the impression that Searle's views might have more wisdom than they are generally credited for in the A.I. community.
I am interested in Thomism and, knowing Feser to be a Thomist, was hoping for a good, thorough exposition of the hylomorphic dualist theory which is the subject of the last chapter. Alas, I found that chapter all too short. I still do not understand how the soul (mind) can be the form of the body, largely because I do not understand the term "form."
Feser defines form as follows: "The form of a substance is its organizational structure; the matter is that which is given organizational structure by the form." (p. 220) He gives the example of a chair having a round seat, and says "the roundness is an aspect of the chair's form." This suggests that the form of a physical thing is its shape. But then he says the seat's roundness is not part of the chair's substantial form, because the chair might have a square seat, but it must have some kind of seat, and that is part of its form. In the Glossary, he states: "The form of a thing is its organizational structure; something irreducible to the sum of its parts." (p. 245) The thing having a form is not the sum of its parts, so is the form how the parts are put together -- an assembled chair, for example, as opposed to a collection of chair parts ready to be assembled? That works very well for physical things, given a low-grade sense of "sum of parts" (so that the same "sum of parts" would exist no matter how the parts were configured or arranged) -- but how does it get us out of mechanism and materialism? And how does it apply if the form is subsistent, i.e., having an immaterial operation, so that it is capable of existing without matter, And how, especially, does it apply to the angels, which never have any matter, so no parts needing to be assembled?
He goes on to describe the forms (souls) of living things. The forms of plants ("nutritive souls") are "the sort which informs the matter of which plants are composed, and imparts to them powers of nutrition, growth, and reproduction." (p. 221) The forms of animals ("sensory souls") give them powers of perception and appetite, as well as the powers of the nutritive soul. And finally the forms of human beings ("rational souls") give us the powers of intellect, will, and memory, in addition to the powers of the animal soul. But some would contend that even the rational soul's powers are completely accountable for by means of the composition of the material parts and the laws of physics and chemistry. This contention becomes more plausible if we press it down to the powers of the animal soul being so accountable, and even more plausible if we push it down to the nutritive soul of plants. So it remains very unclear to me how the soul (any of these three kinds) is a form that is clearly distinct from some composition or arrangement of pieces of matter.
Altogether, then, I am happy with most of the book, but disappointed with the last chapter. At least, though, that chapter, like the rest, has a good bibliography.
The next stop in my quest for understanding hylomorphic dualism will be David Oderberg's Real Essentialism. If anyone has any better suggestions, please let me know.