Harvard University Press, $35, 464 pp.
The task of the public intellectual is to ensure that important areas of common life (public policy, cultural activities, moral understandings, and so on) live up to the standards thoughtful reflection reveals. The United States has not proved the most fertile ground for this sort of person, but now and then contenders arise, and Martha Nussbaum is surely one of the more formidable candidates of our time, discharging the responsibilities of that role with a dizzying industriousness. She has testified in a high-profile Colorado court case involving homosexual rights, articulated an ideal of liberal education intended to guide our colleges, and worked with a range of organizations addressing the condition of women around the world, all the while maintaining her own furious pace of scholarly production. In Frontiers of Justice she brings her considerable talents and energy to a set of questions which, she persuasively argues, public discourse and philosophical reflection have too long ignored: namely, what are our obligations to the disabled in our midst, the poor around the globe, and nonhuman animals everywhere?
Since this question raises issues of justice and collective action, one...