Modern Theories of Justice.

By Serge-Christophe Kolm

Cambridge, MA: The MIT 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 cor responding 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.

As is always the case when one attempts to build a general theory, however, the forest looks more beautiful than some of its trees, and parts of the book do not escape from that rule. Professor Kolm, indeed, sometimes seems to draw conclusions before having explored all the possible counterarguments. For instance, the equal duration income equalization is presented as a solution to the inefficiency associated with multidimensional equality. Even though it solves the problem in some cases, it is far from obvious that it eliminates inefficiency in all cases, in particular if we think that production capacities are not only given by nature but are also derived from schooling choices, which in turn depend on the reward schemes.

On the other hand, the quality of the exposition is not always commensurate with the quality of the contents. In particular, the author does not always avoid repetition, and some chapters would have been easier to read if the author had chosen a more formal presentation (e.g., the chapter on inequality measures).

It should be clear, however, that these shortcomings do not prevent the book from being a major contribution to normative economics. Actually, this contribution goes deeper than the presentation of a general theory of justice. It is also methodological. It is indeed a clear lesson to draw from this book (as well as from any book by Professor Kolm) that any normative inquiry should begin with an interpretative step (the hermeneutics of the problem) where the nature of the problem is scrutinized so as to deduce the domain of its solution and definitions of what should be equalized, and what is to be measured. From this exercise follows the list of justice criteria, properties, and axioms that can be considered as relevant, and consequently the list of solutions that should be a priori excluded. This interpretative step is particularly necessary when a solution is required to satisfy robustness properties across different problems, such as Arrow's Independence of Irrelevant Alternatives property in social choic e theory. Prior to the definition of such properties, the list of possible values for the parameters should be clearly identified and the reasons why parameter values may vary should also be made explicit. This step is necessary to justify why the problem is not modeled as, for instance, a problem of uncertainty, sequential decision making, or a fixed agenda. The interpretative step has also proved extremely useful in the construction of inequality measures, in particular for the distinction between properties imposed to relative, absolute, or other measures.

This methodology is not new, but Professor Kolm has certainly developed and used it the most convincingly and fruitfully. Whoever follows Professor Kolm's method, even to analyze specific, microjustice questions, is protected against the criticism of having developed a purely abstract or mathematical work.

In spite of its few shortcomings, Modern Theories of Justice should be recommended to all the readership interested in normative economics. The book is a major illustration of how justice issues should be dealt with by economists. It should be used as an introduction to Professor Kolm's works, which could then receive the attention they should have already received for decades.