  Reid believes that we can conceive of non-existent objects. This does not appear to comport with his alleged common-sense philosophy, creating an interesting conundrum for Reid interpreters. The best approach to understanding why Reid says we can conceive of non-existent objects is to put this in the context of Reid's opposition to skepticism. In the face of ‘veil of conception’ skepticism, Reid is intent on defending the transparency and self-knowledge of our thoughts. This leads him to argue that we can conceive of non-existent, fictional objects: “I conceive a centaur. This conception is an operation of the mind, of which I am conscious, and to which I can attend. The sole object of it is a centaur, an animal which, I believe, never existed” (EIP 4.2, 321; see EIP 2.12, 160). Suppose when I think I am conceiving of a centaur, I am conceiving of something else, like an image of a centaur. If so, then I do not know the contents of my thoughts. This yields skepticism about the contents of my thoughts, which Reid believes is false. So, by reductio he concludes that we are able to conceive of objects that do not exist.