In a discussion of human institutions and modes of conduct, a basic analytical shift from absolutism to relativism is noted. From this frame of reference the conceptual changes in mathematics, the sciences, and esthetics are reviewed. The paper also discusses the implications of this change for the psychology of human thinking and for children's thinking in particular. Two processes are postulated: "the expression of possibilities" and "the analysis of implications." Each process, moreover, involves very different attitudes toward error. Children who are skilled in the analysis of implications but poor in expressing conceptual possibilities have an overly severe attitude toward their own errors and, therefore, may avoid risk-taking, potentially innovative, activities. The"hardware revolution" in education--instruction by teaching machines and computers--not only stultifies the process of expressing possibilities but will inevitably lead to increased stress on a curriculum that can be taught by machines. This may in fact lead education back to an overly rationalistic view of thinking processes. (NH)