  Even in difficult cases of thoughts about things like centaurs or circles (EIP 4.3, 323–4), their intentional contents are so transparent in a moment's reflection that we can identify them without mistake. Reid presses this epistemological point into heavy service in the context of the conception of non-existent objects. As with Reid's appeal to the irreducible intentionality of conception, Reid's position regarding the conception of non-existent objects has proven challenging to explain and to defend, but starts have been made (David 1985–6; Nichols 2002). Though his commitment to the importance of self-knowledge and the transparency of thought is obvious, Reid jeopardizes his allegiance to common sense by asserting we think of non-existent objects directly and without thinking of a mental intermediary.