Questions similar to the ones we can ask about Plato's rationalism, can be asked about Descartes' version: What are Descartes' clear and distinct ideas? Clear and distinct to whom? Him? His contemporaries? To me, they do not seem so clear and distinct that I can stake my thinking - and thus my sanity and survival - on them. Many people have not known what he was talking about. Not in any language. Yet they were, and are, fully human people. Descartes’s favourite clear and distinct ideas—the basic ideas of arithmetic and geometry—are unknown in some human cultures.

This evidence suggests strongly that Descartes’ categories are simply not that clear and distinct. If they were inherent in all human minds, all humans would develop these ideas as they matured, a point first noted by Locke. Looking at a broad spectrum of humans, especially those in other cultures, tells us that Descartes’s clear and distinct ideas are not built in. We acquire them by learning them. Arguing that they are somehow real, and that in the meantime sensory experience is illusory, is a way of thinking that can then be extended to arguing for the realness of the creations of fantasy writers. In The Hobbit, Tolkien describes Ents and Orcs, and I go along with the fantasy for as long as it amuses me, but there are no Ents, however much I may enjoy imagining them.

                                  

                                                            J.R.R. Tolkien (1916) (credit: Wikipedia)