Progress, unity, and three questions about incommensurability

This article examines the relationship between unity and progress in psycho logy. It contends that psychologists have traditionally sought unity in ord er to fulfill positivistic criteria of progress and success. In accordance with innovations in the philosophy of science, and in accordance with recen t trends toward methodological pluralism, such unity is neither required no r recommended. However, a problem that arises under the new philosophy of s cience - incommensurability - must also be addressed. It is argued that bef ore psychology can be a coherent (though pluralistic) discipline, three imp ortant questions pertaining to incommensurability must be answered.