As an attempt at a systematic theory logic has to start somewhere. Its "raw data" are our intuitions, our inferential practice, and our reflective judgments. Now, we have no guarantee that these cohere well: in fact there are tensions. At the very least, we may find it difficult to construct a systematic account that accommodates all, or even most, of the raw data. A systematic theory may therefore lead us to refine (i.e. revise) our intuitions and change our practice. Logic is a much less cut-and-dried affair than many text-books suggest.