Abstract

The question of incommensurability is an overlooked issue that has profound consequences for our ability to understand relationships and utilize common standards for comparison, contrast, and evaluation in psychology. Are the differences among discourse communities so deep that there is no common "commensurate" &emdash; no common measuring stick for making comparisons among communities? If so, then the community of communities, the discipline of psychology, has no way to compare competing knowledge claims, and no way to effect disciplinary unity and coherence. Kuhn's distinction between incommensurability and incompatibility is described, along with its challenge to Enlightenment rationality and scientific method for brokering the relativity among discourse communities. Popper's misconception that this challenge implies an "anything goes" nihilism is also discussed, specifically his misconception that incompatibility and incommensurability mean incomparability. On the contrary, the article shows how recognizing the incommensurable is often the key to comparison, and thus disciplinary coherence and unity