In his first lecture, Durlauf pursued a key ethical question raised by Professor Heckman: what is the optimal level of inequality? He asked if there is some society-level utility function that an optimal level of inequality could maximize, and to what extent we should focus on equality of opportunity versus equality of material possessions. Previous research presents a number of options that vary in their appeal. The use of a social welfare function (the utility function of a social planner who cares about some function of the welfare of each individual) rules out Pareto inferior policies; for example, we could maximize the average utility by splitting wealth equally. Another option is the Rawlsian solution, in which the planner's utility is defined by the utility of the least well-off person. However, the Rawlsian solution can be shown to be unappealing with simple counterexamples, and the assumption of a "thick veil of ignorance" is difficult since typical economic analysis assumes that individuals are aware of their endowments and resources to some extent. Durlauf explored multiple conceptualizations of the optimal levels of opportunity on the individual level; these include the distinctions between responsibility for one's actions but not one's endowments, and Sen and Nussbaum's approach of linking individual welfare to a "freedom set" of possible actions.