Here is how it begins:
This book, the first volume of a planned trilogy, is an attempt to locate human nature in the broader scheme of things. Its author describes his enterprise as an exercise in philosophical anthropology (that is, an investigation of the concepts and forms of explanation characteristic of the study of man), and hence as a venture in metaphysics, if by that we mean an investigation into the most general structural concepts that inform our thought about a given domain. The basic orientation of the book is thus shaped by very familiar, even canonical, modes or genres of philosophical writing; and there is something equally traditional about both the picture of human beings that its author paints and the representational technique he employs at the most general level in order to do so. For Hacker in effect aims to depict the nature of human beings by determining their genus and species, and so deploys a sophisticated version of a definitional strategy at work in Plato’s dialogues – locating the concept at issue by identifying the more general concepts under which it falls, and distinguishing it from other concepts on the same level of generality.
Accordingly, human beings are here characterized as animals with a distinctive range of abilities. Like all animals, human beings are not merely material entities (spatiotemporal continuants) and substances (persistent individual things that are classifiable into various substantial kinds) but distinctively animate substances. They ingest matter from their environment and metabolize it (as do plants); but they are also sentient and self-moving – the two complementary powers of animal agency, in so far as such a creature’s ability to learn how things are in its environment by means of its sense-faculties and its passive powers of sensation is exhibited in its differentially responsive behaviour. What distinguishes the human animal from other animal species is its abilities of intellect and will (themselves understood as dependent upon the fact that humans are language-users). The former category includes thought, imagination, memory, reasoning and self-consciousness; the latter includes the ability to act on the basis of reasons, and to reflect on the desires, emotions and attitudes which generate our goals and purposes in the light of our own conception of our good and of the good. As a result, we are also subject to a variety of emotions of self-assessment (guilt, shame, pride) which are foreclosed to animals lacking self-consciousness. It is these distinctive capacities and their exercise that give human beings the status of persons. For whilst ‘human being’ is a biological category, ‘person’ is a moral, legal and social one: it means being a subject of moral rights and duties, standing in reciprocal relations to other moral agents, and with a capacity to know and to do good and evil.
Stated with such summary generality, this account is bound to, and is intended to, seem utterly familiar, for it is essentially designed to be a perspicuous survey of the most basic concepts in terms of which (Hacker avers) we have long made sense of ourselves. The true value of the book lies elsewhere, in its ability to show how, at a level of much finer detail and intricacy, these familiar terms of self-understanding both hang together internally and cohere with our basic conception of the world as a whole, and in its willingness to engage in critical detail with the various ways in which philosophers past and present have misrepresented the terms of this self-understanding, or have mistakenly come to think (not always because of such mis-representations) that they can no longer be taken seriously.