The paper claims that Hume ’s philosophy contains an ontology, i.e. an abstract exhaustive classification of what there is. It is argued that Hume believes in the existence of a mind-independent world, and that he has a classification of mind-related entities that contains four top genera: perception, faculty, principle and relation. His ontology is meant to be in conformity with his philosophy of language and epistemology, and vice versa. Therefore, crucial to Hume ’s ontology of mind-independent entities is his notion (...) of ‘supposing relative ideas ’. Entities that are referred to by means of ordinary ideas can be truly classified, whereas entities that are referred to by means of relative ideas can only be hinted at. When Hume ’s ontology is highlighted and systematised, his notion ‘the faculty of imagination’ becomes highly problematic. However, the exposition also makes it clear that Hume deserves the honorary title: the first cognitive scientist. (shrink)