The four main essays in this volume investigate new sectors of the theory of decision, preference, act-characteristics, and action analysis. Herbert A. Simon applies tools developed in the theory of decision-making to the logic of action, and thereby develops a novel concept of heuristic power. Adapting ideas from utility and decision theory, Nicholas Rescher proposes a logic of preference by which conflicting theories proposed by G. H. von Wright, R. M. Chisholm, and others can be systematized. Donald Davidson discusses difficulties in specifying the structure of action sentences to elucidate how their meaning depends on that structure. G. H. von Wright devises a method for describing each \u201cstate of the world\u201d that results from an action, in a revision of his own earlier work. Additionally, a study of the logic of norms by Alan Ross Anderson is presented as an appendix, along with an appendix by Rescher outlining the aspects of action.