The purpose of this paper is to clarify the concept of a reanalysis so as to make it more available for the explanation of historical changes of verb stems. I suggest first that the logical base of a reanalysis should not be an analogy but an abduction. A synchronic grammar including phonological rules, morphophonological rules, and any regularity such as a vowel harmony would be laws(of deduction); surface forms would be results"(of deduction). So from these laws and results the listener abduces a different underlying form (=case" of deduction) from the speaker's in the same synchronic grammar
