Modern Theories of Justice By Serge-Christophe Kolm. Cambridge, MA: The M1T Press, 1998. Pp. ix, 525. $42.00. Professor Kolm's books and articles form one of the most important contributions to contemporary social ethics. Even though the main parts of his works were originally published in or have been translated into English, they have not received the attention they deserve. This is sufficient reason to highly recommend his Modern Theories of Justice, which contains a detailed introduction to his other books. Since the late fifties, Professor Kolm has developed a general theory of justice. He has also extensively contributed to the critical evaluation of the various theories, principles, or criteria of justice that influence economists. Professor Kolm presents his theory of justice as resulting from an application of rationality (in the sense of rational justification) to the question of global justice (what should be done in society?), that is, to the definition of the social optimum and of what is right or good in society. Briefly, this social optimum basically consists of first satisfying basic needs and guaranteeing basic rights and second allocating society's resources (including human resources) in an equitable way. The latter principle requires mixing the (somehow competing) moral criteria of equal process freedom (freedom to benefit from the results of one's acts), equal consumption, and equal satisfaction. Process freedom alone justifies free markets and no resource redistribution. Equal consumption, when combined with efficiency, requires superequity (that is, no agent would strictly prefer any convex combination of the allocations received by others to his own allocation). Equal satisfaction requires to leximin welfare levels corresponding to fundamental preferences, a (difficult) concept that allows the social observer, in particularly unjust or unequal situations, to unambiguously identify the worst-off agents, that is, the agents who should be allocated more resources. Among the different ways of mixing process freedom and equal consumption, Professor Kolm elaborated a particularly interesting intermediary case in recent contributions (recall that the whole structure of his theory, including the ideas of the maximin in fundamental preferences, income justice and superequity, unjust inequality measurement, etc., was first developed and presented in the late sixties). The purpose of this intermediary case is to equally share the benefits of possibly unequal productive capacities while letting agents individually benefit from their own consumptive capacities. The solution consists of a fixed-duration income equalization. This criterion is met when all agents in a society face a budget set having the property that by choosing a prespecified labor time (the so-called fixed duration) any agent would earn the same labor income. Professor Kolm's theory of justice also considers several reasons why the first-best social optimum could not be reached (for example, market failures) and proposes solutions to these problems (for example, social contracts, which give foundations to a theory of the state). Finally, a large part of the book is devoted to a critical appraisal of the main ethical theories influencing the development of normative economics (what justifies the title of the book), with a long discussion on utilitarianism and social choice theory. The general picture is quite impressive. Professor Kolm is not only able to discuss a long and diversified series of topics, such as the economics of poverty, the no self in Buddhism or the ideology of the French Revolution, but he also succeeds in building links among all these topics and integrating them into a unified theory. …