  The same ambiguity with respect to the ontological status of categories that we find in Aristotle is found in many of his medieval commentators. Perhaps this can be taken as a sign that they believe categories to be realities, concepts, and linguistic terms, that is, that categories are ways in which the world is, ways in which we think about the world, and ways in which we speak about the world. However, there are some who argue for purely linguistic or conceptual ways of understanding categories. In modern philosophy, the emphasis shifts toward the language of thought, a prime example of which is Immanuel Kant (1724–1804; see Gracia 2000).