This paper aims to discuss some aspects of the Marty–Husserl debate about grammar. My suggestion is that the debate is first of all an epistemological debate, that is, a debate about what a priori knowledge is and how it is acquired. The key opposition is between Marty’s Brentanian notion of ‘analytic intuition’ and Husserl’s Bolzanian notion of ideation. As I will argue, the underlying issue is the possibility of a psychological a priori. On the one hand, analytic intuition provides the (...) psychologist with a priori knowledge about empirical facts. On the other hand, ideation provides the logician with entities that are disconnected from empirical facts—entities which are ‘purely logical’. I conclude with some brief remarks on the Brentanian background of both conceptions. (shrink)