Cursus Philosophicus Thomisticus, Prima Pars Artis Logicae

Concerning relatives, note that we are speaking of the grammatical relative, such as “who,” “another,” and so forth, not the logical relative, which belongs to the category of relation. Such a relative is defined as “recollective of a thing mentioned earlier.”

It is divided into a relative of substance and a relative of accident. A relative of substance refers to its antecedent in the manner of a substance, as “who,” “that one,” and so forth. A relative of accident refers to its antecedent in the manner of a denominative, as “of what sort,” “such,” and so forth. Each of these is either a relative of identity, namely, one that refers to and is taken directly for the same thing as its antecedent, as in “Peter is learned, and he disputes” and “snow is white, and such is a swan”; or a relative of difference, namely, one taken for something other than its antecedent, though it refers to its antecedent obliquely, as in “Peter disputes, and another speaks,” that is, someone other than Peter, where “from Peter” is referred to obliquely; or “snow is white, and another is a crow,” where “another” refers to an accident different from its antecedent.

Finally, one relative is reciprocal, namely, one that signifies a kind of return to its antecedent, as in “A man loves himself” and “Peter is himself”; another is nonreciprocal, namely, one that does not signify such a return, as in “Peter is white, and he speaks” and “Peter, who speaks, is white.” The return consists in this: a reciprocal relative refers to its antecedent not only as subject but also as predicate, for it joins the same thing to itself. A nonreciprocal relative, however, refers to its antecedent as subject, to which it joins something else or from which it separates something else.

There are therefore four rules for relatives.

First rule, concerning the resolution or exposition of a relative: The relative “who,” when placed in a proposition, is resolved or explained by a conjunctive proposition expressed by the phrase “and he.” Thus, if you say “Peter, who is learned, disputes,” it is resolved as “Peter is learned, and he disputes”; “Man is an animal, which is rational” is resolved as “Man is an animal, and he is rational.”

But note two things when resolving a relative. First, sometimes the relative is part of an extreme and occurs with a copula of implication. For example, if you say “Peter, who is learned, disputes,” “who is learned” belongs on the side of the subject and forms one extreme with it; thus that copula is included with the extreme and is called a copula of implication. In that case, then, the relative is not always resolved immediately, but depends on the resolution of its complex. This happens whenever the conjunctive proposition into which it is to be resolved would have a false part if resolved immediately. For example, in “Every animal that is rational is capable of laughter,” “that” cannot be resolved immediately, for the resulting sense would be “Every animal is rational, and it is capable of laughter,” where the first part of the conjunction is false. One must first descend under that distribution, and then the relative can be resolved. Second, when an affirmative proposition containing a copula of implication with “who” is resolved immediately by a conjunction, its contradictory must be resolved by a disjunction. For example, “Some animal that is rational is capable of laughter” has as its contradictory “No animal that is rational is capable of laughter.” The latter cannot be resolved by a conjunction as its affirmative counterpart is, but by a disjunction, because one conjunctive proposition is not the contradictory opposite of another: owing to the word “and,” it has the same universality; the contradictory is instead disjunctive. To avoid these difficulties, it is therefore better not to resolve the relative “who” by a conjunction until after first descending and resolving the whole complex into singular propositions.

Second rule, for the restriction of relatives: When a relative is resolved by a conjunction, the relative in one proposition refers restrictively to its antecedent placed in the other. Thus, in “An animal is rational, and that is capable of laughter,” “that” refers restrictively to animal, namely, to the animal that is rational. To refer restrictively means nothing other than to refer to the antecedent for the supposit for which it is verified. It does not mean that the relative refers to all the terms found in the categorical proposition containing its antecedent. For example, in “Every man is an animal, and he is capable of laughter,” “he” does not mean every man, since nothing can be pointed out that is every man; rather, it means that man who is an animal and for whom “is an animal” is verified.

Third rule, for the supposition of a reciprocal relative: A reciprocal relative supposits with the supposition of its antecedent, so that descending or ascending under the antecedent entails descent under the reciprocal relative. Some call this “sealed supposition,” that is, enclosed under the supposition of another, because it needs no supposition other than that of its antecedent. Thus, in “A man loves himself,” “himself” supposits determinately just as “man” does. In “A mother loves her own son,” “her own,” which is a reciprocal of the derived kind, supposits like its antecedent with respect to the connotation it includes. For “her own” connotes the mother obliquely, that is, it means the mother’s son; and insofar as it is thus connoted obliquely, it supposits like the antecedent itself.

Fourth rule, for the supposition of a nonreciprocal relative: This relative does not supposit with the supposition of its antecedent, but according to the nature of the signs affecting it, like other terms. Thus, in “Every man disputes, and he speaks learnedly,” “he” does not stand distributively but determinately; in “Some animal is rational, and every man is it,” “it” stands confusedly only.