The Meuse near Charny, Meuse, France
A single water molecule doesn’t stream but a river does. Nevertheless a river consists of a countless number of water molecules. Also the countless number of water molecules as such don’t stream. So if we want to study fluvial processes like erosion, the velocity of the flow, the friction between the current and the riverbed and so on, we do not study the movements of the water molecules but we study the river. We don’t say that the molecules erode the landscape but that the river does. Or, a different example, we do not say that the water molecules reflect the sky but that the river does. Confusing river and water molecule is what Gilbert Ryle called a category mistake. In the same way it is a category mistake to confuse mind and brain. Just as a river cannot exist apart from the the water molecules that produce it, so also the mind cannot exist apart from the neurons and what else makes up the brain. In this sense the mind is the brain. Nevertheless it is a category mistake to reduce a typical phenomenon of the mind like thinking to a phenomenon of the brain and its neurons. It is not our brain that thinks but our mind does, i.e. “we” do. Seeing it in a different way is making a category mistake.