Ethical idealization pivots on idealities in the sphere of human action. Cognitive idealization, by contrast, pivots on idealization in the sphere of our knowledge. Accordingly, the task of the present book is to consider the role of idealization in cognitive matters and to establish its utility in this realm. For the somewhat ironic fact of the matter is that our recourse to unrealizable idealities finds its explanation and justification in the substantial benefits that flow from such a proceeding. It is, ironically, in its utility that the rationale of ideality is to be sought.The book brings together lines of thought about the kinship between idealism and pragmatism that have occupied the author’s work for many years.