...In this passage [above], Aquinas contrasts the relations involved in paradigmatic relational situations—namely, relations of the second type—with the relations involved in two sorts of non-paradigmatic relational situation. We are already familiar with relations of the third or ‘mixed’ type from our discussion of creation and intentional relations. Moreover, we can see that Aquinas follows the common medieval practice of connecting relations of this type with both Aristotle’s discussion in the
Metaphysics and the Boethius-inspired example of the column. We have yet, however, to encounter relations of the first type. These are relations comprised by pairs of properties or accidents both of whose members are beings of reason. As an example of this type of relation, Aquinas gives self-identity. When we conceive of a situation involving this sort of relation, he says, we conceive of it as if it involved two things (“a relation requires two
relata” and hence “reason apprehends the one thing twice”), and also as if the two things were ordered to each other by a pair of properties (or “[relative] dispositions”). Obviously, however, there are not distinct things in extramental reality serving as the
relata of the relation of self-identity, much less two properties by which such
relata are related. Like many other medievals, therefore, Aquinas concludes that in this case the relations (or relative dispositions) are not real, but mere beings of reason.[
39]
The claim that self-identity is a relation of reason might seem worrisome. For insofar as relations of reason depend for their existence on the activity of the mind, it would seem to follow that something’s being self-identical is mind dependent. But
that is absurd.
Aquinas is aware of this sort of worry. In fact, in one of his disputed questions, he imagines a similar worry leading someone to doubt the view that even God’s relation to his creatures can be considered a relation of reason:
After all, if there were no created intellect in existence, God would still be Lord and Creator. But if there were no created intellect in existence, there would not be any beings of reason. Hence ‘Creator’, ‘Lord’, and terms of this sort, do not express relations of reason. (De potentia, q. 7, a. 11, obj. 4.)
This sort of worry about relations of reason helps to explain what is perhaps their most significant effect on the medieval discussion of relations—namely, a gradual shift away from the traditional Aristotelian characterization of relations. On this characterization, as we saw earlier, relations are identified at least partly in terms of their metaphysical function—that is to say, they are identified as items that actually serve to relate things. But in order to maintain that things can be self-identical apart from the activity of any mind, while at the same time maintaining that self-identity is a relation of reason, medieval philosophers have little choice but to move away from the traditional characterization. And of course the same thing is true in the case of God’s relation to his creatures. Thus, as Aquinas says in reply to the abovementioned doubt:
A man is really (and not merely conceptually) identical to himself, even though his relation [of self-identity] is a being of reason. And the explanation for this is that the cause of his relation is real—namely, the unity of his substance, which our intellect considers under the aspect of a relation. In the same way, the power to compel subjects is really in God, and our intellect considers this power as ordered to the subjects because of the subjects’ order to God. It is for this reason that he is really said to be Lord, even though his relation is a mere being of reason. And for the same reason it is evident that he would be Lord [Creator, etc.] even if there were no created intellect in existence. (De potentia q. 7, a. 11, ad 3–5.)
In this passage, Aquinas makes it clear that in cases involving relations of reason—such as self-identity or God’s relation to the world—the
relata are related, not by their relations (since these are mere beings of reason and hence dependent on the activity of the mind), but by what he refers to here as the
cause of their relations.[
40] Now, in the case of a man’s being self-identical, Aquinas says the cause is just “the unity of his substance,” where by this he seems to mean that what makes a man identical to himself is just the man himself. Again, in the case of God’s being Lord he says that the cause is “the power to compel subjects”. In the case of God, however, Aquinas does not think the power to compel subjects is distinct from its subject, namely, the divine nature. Hence, he maintains that what makes it true that God is Lord is nothing but God, his creatures, and some property or attribute of the creatures.
In effect, therefore, reflection on relations of reason brings about a shift away from the conception of relations as items that relate, and thus forces medieval philosophers to fall back on what they might otherwise have thought of as an equivalent characterization, namely, the view that relations are items corresponding to or signified by our genuinely relational concepts. Thus, even if self-identity or God’s relation to the world is a mere being of reason, and hence does not actually relate its subject to anything, nonetheless it can still be regarded as a relation on the grounds that it is signified by a relational concept. Now obviously this shift away from the traditional Aristotelian conception has the awkward consequence that things can be related even if their relations do not exist. Thus, Socrates can be identical to himself even if there is no self-identity, God can be Lord of creation even if his relation of Lordship does not exist, and more generally, a predication of the form ‘
aRb’ can be true, even when no predication of form ‘
R-ness exists’ is true. Of course, there is nothing ultimately incoherent about this consequence, provided we keep in mind that the relations in such cases are mere beings of reason. Nonetheless, accepting this consequence does force medieval philosophers to deny what at least initially appears to be a truth of reason, and at any rate is part of common sense—namely, that things are related by their relations.