This is a review of _Whose Justice? Which Rationality?_ by Alasdair MacIntyre.
This is a very challenging book to read, but also one that will deepen your thinking about the world, whether you agree with it or not.
We largely take it for granted that (1) people disagree significantly about a wide range of issues related to ethics, and that (2) people do not agree about enough standards of rationality to resolve these ethical disagreements. MacIntyre puts this by saying that "logical incompatibility and incommensurability" both obtain (p. 351). What conclusion should we draw from these facts? One common response is relativism, which is roughly the view that the truth or falsity of a claim depends on the perspective from which it is evaluated. However, MacIntyre argues against relativism based on a brilliant reinterpretation of several major Western philosophical traditions.
The Western Englightenment (of which Descartes is paradigmatic), rejected appeals to tradition, canonical texts and authority, and attempted to put in their place the "appeal to principles undeniable by any rational person," and hence independent of culture, history, etc. "Yet both the thinkers of the Enlightenment and their successors proved unable to agree as to what precisely those principles were which could be found undeniable by all rational persons" (p. 6). Since the Enlightenment, most Western thinkers have either (1) continued to search for principles that are universally acceptable to all minimally rational humans (and continued to fail in this quest), or (2) given up on the quest for universal principles of reason, but -- paradoxically -- continued to assume the Enlightenment prejudice that any rational justification would have to be universal, ahistorical, and acultural.
MacIntyre suggests that neither approach has learned the lesson of the failure of the Enlightenment project, which is that any rational justification has to be parochial, historical and in a particular cultural context.
Since rational justification must be historical, the bearers of justification are not "theories" in the abstract, but embodied traditions. MacIntyre examines four sample traditions in this book (although he admits there are many more): the Aristotelian-Thomistic, the Augustinean, and those of the "Scottish Enlightenment" and modern liberalism.
Traditions like these can undergo "epistemological crises": situations in which a tradition, by its own standards, increasingly discloses "new inadequacies, hitherto unrecognized incoherences, and new problems for the solution of which there seem to be insufficient or no resources within the established fabric of belief" (p. 362). A tradition may find a way to survive such a crisis (as Thomas Aquinas helped Christianity to do by synthesizing Augustineanism and Aristotelianism), but it may also fail. And because the possibility of failure is there, relativism is false: a tradition can come to see that its claims are false even by its own standards.
Even if my tradition is not in an obvious crisis, I can realize that I have a rational justification for rejecting or modifying it. Suppose I am confronted with an alien intellectual tradition which is both incompatible and incommensurable with my own. Because the two are incompatible, I cannot simply agree with both traditions. But because of incommensurability, I cannot directly convince the adherents of the rival tradition that they are wrong (nor can they directly convince me). I can, however, learn to be "bilingual" in the two traditions. The Aristotelian can learn, for example, to "speak Confucian," as it were. Having done so, he occupies a special perspective, from which he may conclude that the Confucian worldview offers a superior interpretation of the strengths and weaknesses of his own tradition. Or he may conclude the opposite. Or he may conclude that some sort of synthesis is possible, which is superior to either one individually. For this reason also, relativism is not true, despite the fact that traditions are, when speaking one to the other, incommensurable: someone occupying one tradition *can* see that his views are fundamentally mistaken.
MacIntyre argues that, of the four traditions he considers in this book, three have entered inescapable epistemological crises, while one (the tradition of Thomas Aquinas) has answered all challenges so far. The bulk of the book is a history of the four traditions. If you want to get the outline of MacIntyre's view, I recommend chapters 1 (the intro), 7-8 (on Aristotle), 9 (on Augustine), 10-11 (on Aquinas's synthesis), 16 (on Hume), 17 (on liberalism), and 18-20 (MacIntyre's grand theory).
This is, of course, an easier book to read if you have read some previous philosophy (Thomas Kuhn's _The Structure of Scientific Revolutions_ is in the background of much of what MacIntyre says, even though he doesn't cite Kuhn very often), but a bright, motivated non-philosopher can read and greatly enjoy this book too.
