Because for Aquinas the ground of all of our knowing, both of the concepts we form of things and the indemonstrable first principles or fundamental axioms of thinking which we immediately and intuitively know must be true (as we will see presently), is a fundamental encounter with the actuality of being, he regards these aspects of logic as ‘first intentions.’ These are the concepts and axioms we use to understand real things. The relations among and classifications of concepts (predicables) we use in logic to give our concepts of things (first intentions) precision and order, and so to understand real things well (genus, species, difference, etc.) are ‘second intentions;’ they are thoughts about thoughts, concepts to clarify concepts of real things.
For instance, when we say that dog is a universal, we are thinking of it as the object of an operation of reason, the operation of predicating. We mean that dog is something predicated of many individuals. Or if we say that dog is a species of animal, we mean that in the definition of dog, the genus-term is animal. We are seeing dog as an object of reason’s operation of defining. Thomas follows the usage of his day in calling such features—universal, species, genus, and other terms of logic applied to things—“logical intentions.” He even speaks of logic as the science of such intentions. And he says that such intentions are “extraneous to the natures of things.”[1]
Thus, logical relations form their own order, an order apart from the order in nature and our knowledge of that order. The logical order can thus seem purely abstract and formal, the result of our own rationalizing ability. This can then give rise to confusions about the real order. But for Thomas, the two are clearly distinct.
There is an order we construct in knowing natural things, one piggyback on our knowledge of them. Thus animal is called a genus and man a species. “Animal” and “man” signify things that are; genus signifies a relation that attaches to knowing them, that of being predicable of many specifically different things. Species attached to man means that “man” is predicated of many numerically different things. These second-order words are logical words, signifying logical not real relations.[2]
Because Thomas recognizes that predicables (genus, species, specific difference) signify logical relations, he can dismiss the theory that there must be in the human soul, which is a real principle in individual humans, a form of animal, and a form of rationality (as well as a form of living, and a form of body).
Thomas does find some thinkers taking merely logical features of things, or the relations among such features, for real features or real relations, and as a result, falling into no little confusion. … [T]he twelfth-century Jewish thinker Solomon Ibn Gabirol, or Avicebron to the Latins, [a]s Thomas reads him, … took each differentiating term in the definition of a substantial kind to stand for a distinct form in the substance; and he took what the most general term stands for, substance itself, to be the substrate and matter of all things except God. … This is “altogether repugnant to reason,” Thomas says, because matter is to form as potency to act, and potency is “less of a being” than act.[3]
As we will see when we treat of Thomistic psychology, each substance has just one substantial form, and the form of a human body, which is the human soul, is itself the one principle of life, of sentience (animality), and of reason.
[1] Stephen L. Brock, The Philosophy of Saint Thomas Aquinas: A Sketch (Cascade Books, an Imprint of Wipf and Stock Publishers 2015), Kindle Edition., pp. 98-99.
[2] Ralph McInerny, Aquinas (Polity 2004), p.41.
[3] Brock, op. cit., pp. 100-101.
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