Conceptual Comparison and Conceptual Innovation

The guiding idea of this paper is that discussions of comparisons of concepts across theories (individuals, historical periods, cultures) and the introduction of new concepts must be based on an account of how the content of concepts is determined. I will sketch a theory of concepts based on the work of Wilfrid Sellars, although with several modifications.1 Then I will illustrate the application of this theory in two cases. First, I will compare the concepts of earth, water, and air as they appear in Aristotelian physics and in Galileo. Second, I will consider the concept of an isotope, an example of a new concept whose introduction is fairly well localized in the history of chemistry. There are two general conclusions that I want to draw from this discussion. First, a Sellarsian approach provides a specific set of tools for comparing concepts and introducing new concepts. Second, major conceptual change can take place while maintaining a great deal of continuity with existing conceptual resources.