 In natural philosophy and metaphysics Marsilius was an empiricist, meaning that he thought all scientific knowledge must be based on either sense data or self-evident propositions, i.e., propositions in which the meaning of the predicate is included in the subject. Everyone who knows the meaning of the terms of such propositions judges them to be evidently  true.[18]  This has far-reaching consequences for the relationship between philosophy and theology. Since the philosopher uses only sense data and self-evident propositions, his inquiry may come to different conclusion than that of the theologian, who has additional knowledge from Scripture. The philosopher makes judgments about the world from a limited human perspective, whereas the theologian is helped by divine  revelation.[19]  Yet Marsilius took the task of the philosopher seriously because he thought the human mind has a natural tendency to search for truth, which is satisfied (although not ultimately satisfied) in natural philosophy and  metaphysics.[20]