# **1. Introduction**

This paper critically reviews a branch of literature that has recently developed in the intersection between normative economics and distributional analysis, and which concerns itself with the definition and measurement of inequality of opportunity. This literature was inspired by a debate that took place in political philosophy during the 1970s and 1980s. Beginning with John Rawls (1971), a number of authors renewed and reinvigorated the egalitarian project by progressively moving the “demand for equality” from the realm of individual achievements to the space of opportunities. This was achieved by proposing a version of egalitarianism that does not deny but, on the contrary, explicitly recognizes the role of individual responsibility. As Cohen (1989) writes, this literature "[...] has performed for egalitarianism the considerable service of incorporating within it the most powerful idea in the arsenal of the anti-egalitarian right: the idea of choice and responsibility" (Cohen 1989, p.993). For this very reason, it is argued, equality of opportunity is now the prevailing conception of social justice in contemporary western societies.

Economists soon followed where political philosophers had first treaded: Beginning in the 1990s, considerations of personal responsibility and opportunities began to feature in formal economic theories of the evaluation of social states. After influential contributions by John Roemer and Marc Fleurbaey, mainly devoted to the identification of opportunity-egalitarian policies and allocation rules, in the last fifteen years a substantial literature has emerged which seeks to assess the degree of inequality of opportunity in different countries, and to evaluate the opportunityequalizing effects of social and economic policies.

The literature is now sizable. A number of different measurement and evaluation methodologies have been proposed and an even broader array of empirical applications has been undertaken. Inequality of opportunity has been analyzed in different spheres of human life and for different domains of public policy, ranging from income distribution and income taxation; to health and health care; educational achievement; and anti-poverty policy. In light of this broad scope, this paper makes no attempt at being exhaustive. We aim only to provide a flavour of recent research in this field, and interested readers are also referred to two excellent recent surveys by Roemer and Trannoy (2013), and Ramos and Van de Gaer (2012).

The paper is structured as follows. The next section contains a very brief overview of the philosophical foundations of the theory of equality of opportunity (E.Op.). Section 3 then reviews the two main families of approaches to the economic analysis of E.Op.: the _direct approach_ , which seeks to characterize people’s opportunity sets directly; and the _indirect approaches_ , which define equality of opportunity in terms of a distinction between two categories of determinants of individual achievement: those within the realm of personal responsibility, and those beyond it. The family of indirect approaches is anchored on two fundamental principles of equality of opportunity: the compensation and reward principles, which are also discussed in Section 3.

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