By Richard A. Posner, Harvard University Press, Cambridge, Mass., 402 pages, $25.95

‘Hard times, come again no more,” implored Stephen Foster. The plea went unheeded. Relentlessly, the business cycle has continued to inflict its periodic cruelties on the deserving and the undeserving alike. In “The Crisis of Capitalist Democracy,” Judge Richard Posner of the U.S. Court of Appeals for the Seventh Circuit analyzes at length the hard times from which we hope we are now emerging. He treats the political as well as the economic aspects of his subject.