LOGIC AND LANGUAGE propositions such as these a judgement, aYrmative or negative, may be made or withheld; if made, it may be made truly or falsely, with or without hesitation, on the basis of argument, or on grounds of self-evidence Aquinas classes exercises of the intellectual powers on the basis of these diVerent possibilities: the withholding of judgement is doubt (dubitatio); tentative assent, allowing for the possibility of error, is opinion (opinio); unquestioning assent to a truth on the basis of self-evidence is understanding (intellectus); giving a truth unquestioning assent on the basis of reasons is knowledge (scientia); unquestioning assent where there are no compelling reasons is belief or faith (credere, Wdes) All of these are instances of compositio et divisio What of the other intellectual activity, the conception of non-complexes? Aquinas seems, in diVerent places, to give two diVerent accounts of this Sometimes he seems to equate it with the mastery of the use of a word In that case someone would have a concept of gold if she knew the meaning of the word ‘gold’ But in other places Aquinas equates a concept with the knowledge of the quiddity or essence of something: in this sense only a chemist, who could link the properties of gold with its atomic number and its place in the periodic table, would have a real concept of gold (ST 1a 3 and 1a 77 ad 3) He was well aware of the diVerence between the two types of concept: he points out, for instance, that we can know what the word ‘God’ means, but we not and cannot know God’s essence (e.g ST 1a 2 ad 2) How close, for Aquinas, is the link between language and thought: what is the relationship between these varied intellectual operations and the corresponding speech-acts? Aquinas believed that any judgement that can be made can be expressed by a sentence (DV 2.4) It does not follow from this, nor does Aquinas maintain, that every judgement that is made is put into words, either publicly or in the privacy of the imagination Again, even though every thought is expressible in language, only a small minority of thoughts are about language On the question of universals, Aquinas’ starting point is a rejection of Platonism, a doctrine that he described as follows: Plato, to save the fact that we can have certain intellectual knowledge of the truth, posited in addition to ordinary bodily things, another class of things free of matter and change, which he called species or Ideas It was by participation in these that all particular tangible objects get called ‘human’ or ‘horse’ or whatever Accordingly, 137