LOGIC AND LANGUAGE Plato held that deWnitions, and scientiWc truths, and all other things pertaining to the operation of the intellect, are not about ordinary tangible bodies, but about those immaterial things in another world (ST 1a 84 1c) Plato was misled, Aquinas thought, by the doctrine that like can be known only by like, and so the form of what is known must be in the knower exactly as it is in the known It is true that the objects of thought in the intellect are universal and immaterial; but universals of this kind not exist anywhere outside an intellect Aquinas was prepared to agree with Plato that there are forms that make things what they are: there is, for instance, a form of humanity that makes Socrates human But he denied that there was any such form existing apart from matter There is not, outside the mind, any such thing as human nature as such, human nature in the absolute There is only the human nature of individual human beings like Peter and Paul There is no human nature that is not the nature of some individual, and there is not, in heaven or earth, such a thing as the Universal Man (ST 1a 79c) Human nature exists in the mind in abstraction from individuating characteristics, related uniformly to all the individual humans existing outside the mind There is no Idea of Human, only people’s ideas of humanity Plato’s Ideas are rejected in favour of Tom, Dick, and Harry’s concepts (DEE 102–7) The humanity of an individual, as Aquinas put it, was ‘thinkable’ (because a form) but not ‘actually thinkable’ (because existing in matter) To make it actually thinkable it had to be operated upon by a special intellectual power, the ‘agent intellect’ We will follow Aquinas’ account of this operation when we examine his philosophy of mind; at present we may ask what are the implications of Aquinas’ anti-Platonic account of universals for the semantics of names and predicates Aquinas spells out the consequences in respect of one kind of universal, namely, a species The species dog does not exist in reality, and it is no part of being a dog to be a species, even though dogs are a species But if being a species were part of what it was to be a dog, then Fido would be a species When we say that dogs are a species, we are not really, if Aquinas is right, saying anything about dogs: we are making a second-order statement about our concepts First, we are saying that the concept dog is universal: it is applicable to any number of dogs Secondly, we are saying that it is a 138