Are discourse communities incommensurable in a fragmented psychology? The possibility of disciplinary coherence

The question of incommensurability is an overlooked issue that has profound consequences for our ability to understand relationships and utilize commo n standards for comparison, contrast, and evaluation in psychology. Are the differences among dis course communities so deep that there is no common " commensurate" - no common measuring stick for making comparisons among comm unities? If so, then the community of communities, the discipline of psycho logy, has no way to compare competing knowledge claims, and no way to effec t disciplinary unity and coherence. Kuhn's distinction between incommensura bility and incompatibility is described, along with its challenge to Enligh tenment rationality and scientific method for brokering the relativity amon g discourse communities. Popper's misconception that this challenge implies an "anything goes" nihilism is also discussed, specifically his misconcept ion that incompatibility and incommensurability mean incomparability. On th e contrary, the article shows how recognizing the incommensurable is often the key to comparison, and thus disciplinary coherence and unity.