The author argues that neither liberal nor conservative concepts about these issues withstand close scrutiny; he calls for less emphasis on political principles and more attention to what does and does not work in specific programs. The book describes how welfare policy was dominated in the early 1980's by conservatives who promoted concepts that justified cutting back sharply on the social programs of Lyndon Johnson's Great Society. They believed that a period of sustained economic growth, with low taxes and free markets, would do more to help poor people than coddling them with government assistance. Despite the economic expansion of the later Reagan years, however, the problems of persistent poverty grew even more serious. In presenting his arguments, the author analyzes major books on such subjects as affirmative action (Thomas Sowell), the "safety net" (Charles Murray), the effects of heredity on learning and propensity to commit crime (James Q. Wilson and Richard Herrnstein), and ghetto culture and the underclass (William J. Wilson). The author's intention throughout the book is to identify the empirical and moral assumptions that traditional ideologies link together, thus helping the reader to see the way various remedial plans actually succeed or fail; for example, he believes that until Aid for Families with Dependent Children is transformed to reinforce rather than subvert American ideals about work and marriage, efforts to build a humane welfare state will never succeed. Subject index and chapter notes