Philosophical ethics generally takes the form of deriving moral principles from arguments based on reason alone. The only bow to empirical reality is, in Kant's phrase, "ought implies can"; i.e., a moral principle must be capable of being followed by normal mortals. This position is virtually forced upon philsophers who accept Hume's critique of the "naturalistic fallacy," according to which it is impossible to derive normative principles from empirical facts alone ("is" cannot imply "ought"), or Moore's argument that "the Good" cannot be reduced to a set of descriptions of the natural world.



Casebeer rejects both arguments, and attempts to develop a naturalistic ethical theory from human nature (evolution) and the structure of the human brain (connectionism), arriving at an Aristotelian "virtue theory" in which the virtuous person strikes the appropriate mean between possible extremes of social behavior. Casebeer's argument is an extended and rigorous defense of Paul Churchland's treatment of moral cognition as a "skill" that is learned by example. "Moral knowledge becomes" Casebeer concludes (p. 105) "...knowledge of the structure of our social environment and how to navigate effectively within it."



Casebeer is an intelligent and engaging writer, and there are many very interesting insights and arguments in this book, which I therefore recommend to others interested in ethics. However, I do not believe Casebeer succeeds in defending his position, and indeed, I think it is quite indefensible.



Ethics, for Casebeer, Churchland, and perhaps even Aristotle, is the study of how people should behave if they are to "flourish" in the sense of maximizing their human potential, which is what is meant by "navigating successfully" in society. Ethical behavior is like good manners and appropriate dress, all of which are higher level social skills that allow one to better cultivate the self. It is thus virtually taken for granted that if one knows what is ethically correct, one will naturally follow its precepts (Casebeer follows Aristotle in analyzing "akrasia"---knowing the right thing to do but choosing not to do it---to "weakness of will" or other forms of irrationality).



This view of morality is of some personal and social importance, but does not cover moral choices that involve sacrificing one's personal well-being on behalf of the well-being of others (e.g., voting, participating in a collective action, saving a drowning child, fighting bravely for one's country), or when to behave in certain ways that are personally costly but have higher moral value (e.g., being honest or working hard). Nor does this view cover basic issues of political ethics, such as when is authority justified, what is the proper division of labor between the sexes, is it ethical to buy and sell bodily organs, and should abortion be legal? These fall completely outside the framework of this book.



The relationship between ethics (even of the limited sort entertained by Casebeer) and connectionism is also less obviously important than the author would have us believe. Connectionism as a psychological theory is itself not highly plausible, despite the voluminous writings of its few advocates, since neural nets reflect some but probably not all of brain structure. Moreover, the only implication of connectionism with ethics that I could ascertain from this book (and the writings of Paul Churchland and other connectionists) is that moral teaching is better accomplished by example than by the listing of basic principles. This may be true, but it does not require connectionism and it is hardly an earthshaking insight.



A final point: there is virtually nothing about evolution in this book.