My work on human capital began with an effort to calculate both private and social rates of return to men, women, blacks, and other groups from investments in different levels of education.

Human capital analysis starts with the assumption that individuals decide on their education, training, medical care, and other additions to knowledge and health by weighing the benefits and costs. Benefits include cultural and other non-monetary gains along with improvement in earnings and occupations, while costs usually depend mainly on the foregone value of the time spent on these investments.

Fines are preferable to imprisonment and other types of punishment because they are more efficient. With a fine, the punishment to offenders is also revenue to the State.

Still, intuitive assumptions about behavior is only the starting point of systematic analysis, for alone they do not yield many interesting implications.

Different constraints are decisive for different situations, but the most fundamental constraint is limited time.

The most fundamental constraint is limited time

Along with others, I have tried to pry economists away from narrow assumptions about self interest. Behavior is driven by a much richer set of values and preferences.