2. Relation
It is evident that created things, each and all of them, are variously related to one another, by equality, by similarity, by causality, etc. There is a type of relation, however, which is more difficult to grasp, though it is quite real, the transcendental relation. This is not our immediate concern, but should nevertheless be sufficiently noted to distinguish it from the relation of which we do have here to speak, the predicamenta1.20 Transcendental relation is an order according to which a thing is of its very nature referred to another; for example, the relation of the will to good, of the intellect to being, and more generally, of potency to act. This relation is not really distinct from the essence of the thing concerned, but
expresses the essence itself in its reference to another. In short, it enters into the very nature of a thing and thus forms part of its definition. By contrast, the predicamental relation has its own reality, distinct from the subject which is referred or related. Hence it does not enter into the definition of the subject but has a nature of its own. 21
a) Nature of predicamental relation. Predicamental relation is defined as an accident whose entire being consists in its reference to another:
accidens cujus totum esse est ad aliud se habere.
The whole essential, then, of this relation is a respect to something else, a "towardness" of some kind. But before the relation can arise certain things, it should be obvious, are required:
For instance, this man (subject) is similar, or is related by similarity to that other man (term) because of his, the subject's, white hair. Of course, the subject is in one sense a term, too, so that we may speak of the two terms or two extremes of the relation.
There are, however, difficulties attending upon the nature of predicamental relation, which have led some to deny its existence altogether. The predicamental relation is supposedly a real accident; yet all its being is comprised in the reference to another, in something which, as it were, hangs suspended outside the subject. How, then, can it still be in the subject, an accident of it, when its very essence consists in pointing to something outside, in the reference itself? Doubtless (we reply) the nature, the proper essential of the relation is reference or "towardness"; nevertheless, the relation cannot support itself, it must have a footing, a flooring, something that receives it. This is the subject, of which it is accordingly an accident, as (say) paternity is something real, but an accidental reality, for a man.
Another (and perhaps deeper) question is whether the relation is really distinct from its foundation. And more generally, if things are already related to each other transcendentally, why superimpose upon them a whole new order of relational entities, the predicamental relations? The answer (to the second question) is that these relations are demanded by the facts of experience; to be related to another constitutes a mode of being, hence a distinct predicament. A clear indication that these relations have an ontological status of their own is seen in the fact that a relation can appear or disappear without its term undergoing any modification in itself. As for the distinction between relation and its foundation, St. Thomas insists it is real; for, among other things, the distinction again meets the test of separability - indeed, the two questions (why relations at all, and what the distinction of relation and foundation?) come to one. Two white objects, for example, are related by similarity. If one object is destroyed, the relation ceases; yet the whiteness, its foundation, survives in the still existing object. But surely, what is really separable is really distinct.
b) Division of predicamental relation. A relation is either real or logical (relation of reason): real, if it exists independently of the mind, as the relation of father to son; logical, if it depends upon the consideration of the mind, as the relation between subject and predicate of a proposition. Predicamental relation is of course real; it meets the requisites of a real relation, which are:
Essentially, predicamental relation is divided according to its foundation. If this denotes that one thing depends in some way upon another for its existence, we have a relation of causality (not to be confused with the exercise of causality); otherwise, when no such dependence is involved, the relation is one of mere agreement or disagreement, the nature of which varies with the foundation. With substance as foundation the relation is one of identity or diversity; with quantity, one of equality or inequality; with quality, one of similarity or dissimilarity.
The accidental division is that of mutual and nonmutual. A mutual relation is bilateral, that is, bilaterally real: to the real relation of subject to term corresponds a real relation of term to subject, as father to son and inversely. The nonmutual relation is unilateral, real from one side, logical from the other. In knowledge, for example, there is a real relation of intellect to thing known, for the intellect depends upon the thing for its knowledge; but the relation of thing to the speculative intellect is only a relation of reason (or logical), because the thing is in no way affected simply by being known. Again, the relation is real from creature to Creator, but not real in reverse order, from Creator to creature.
All of which, in conspectus, reads thus:
<image on p181 here >