Both Rawls and Nussbaum are modern American philosophers with distinguished academic careers whose work has focused mainly on the fields of moral and political philosophy.
Rawls (1921—2002) is best known for his work on the problem of political institutions. His work can be described as updating Kant's ethical theories and considering their implications for political institutions. Rawls was also know for his critique of utilitarianism. His work is grounded in a thought experiment, the "Original Position", which imagines a group of people creating their own society ex nihilo, who are well-informed about people in general but have no notion of the particular circumstances of others within their own society (i.e. people who do not know who will be benefited by which laws). In such a situation, the two main ethic principles become equality and fairness.
Nussbaum (born 1947) also seeks an alternative to utilitarianism, but grounds her work in Aristotle rather than Kant. Her focus is on the nature of the good life or flourishing for individuals, and argues that emotions and the sympathetic imagination are essential to understanding it. She has been an active campaigner for women's rights and gay rights. Her current focus is on "capability theory", which looks at what people are actually able to do in different circumstances as the foundation of a theory of social justice.