Within linguistics there are several theories which deal with syntax. A general division can be made between Chomskyan generative syntactic theories and various functional syntactic theories. This paper addresses the question (i) to what extent these theories and their explanations deal with the same type of phenomena, (ii) to what extent they use the same concept of a successful explanation and (iii) to what extent they are incommensurable in the sense of Kuhn (1962). This topic is addressed by a discussion of a number of generative analyses (case studies), which are analyzed and evaluated from a functional perspective. This analysis shows how a number of phenomena that are analyzed and explained within the generative paradigm can be explained differently from a functional theoretical perspective and framework. The paper concludes that generative and functional approaches to syntax are incommensurable in the sense of Kuhn, even though there are ways to engage in a common discussion about syntax.