Radical Conceptual Change

Michael Strevens (New York University)

When you undergo radical conceptual change, you gain a new concept that enables you to think thoughts that you could not have thought before. Examples include (perhaps) the appearance of the concept of Newtonian force; the separation of the concepts of heat and temperature; young children’s acquisition of the concept of belief. But how is such change possible? It seems that it cannot be the product of ordinary thinking of various sorts, such as inference or stipulation, since these require the concept or something effectively equivalent to exist already. So what psychological process, if any, can introduce a radically new concept? This paper sketches the outlines of such a process, called introjection, and argues that concepts so acquired give the acquirer, as the definition of radical conceptual change requires, the ability to think thoughts that were previously beyond their reach.