<p>There is the difficult question in metaphysics about the possibility of modal knowledge, that is, the possibility of knowing that some facts are necessary or that some facts are contingent. The question is especially demanding when one agrees, as I will, that there are worldly modal facts, but that modality cannot be learnt by empirical means and it must be given a priori. Here I propose an answer that calls in rational intuition for help. In a line, the claim is that metaphysical modal knowledge can be acquired a priori, by intuition into the categorial structure of empirical facts. This form of rational intuition I call categorial intuition. I will also examine causal knowledge as an exemplary case of metaphysical modal knowledge by categorial intuition.</p>