Cursus Philosophicus Thomisticus, Prima Pars Artis Logicae

Ampliation is defined as “an extension of a term from a lesser to a greater supposition,” as “A man can be just” is extended to possible men. Restriction is “a contraction from a greater to a lesser supposition,” as “A man who is just is wise” does not stand for every man, but only for one who is just.

To understand these definitions, note that a term can be amplified or restricted in two ways: first, with respect to more or fewer supposits to which it belongs; second, with respect to more or fewer times in which it is verified. In the first way, ampliation and restriction occur only in a common term, since only a common term has individuals to which it can belong. Therefore this kind of ampliation and restriction is found only in accidental personal supposition. Simple supposition does not pass to individuals, while natural supposition belongs absolutely to all; only accidental supposition can belong to more or fewer. For example, “Every man is colored” is said of more than “Some man runs,” and “A just man is wise” of more than “A man is wise.” In the second way, ampliation and restriction also belong to a singular term, since a singular can be verified across several differences of time. A term is then said to be amplified with respect to temporal differences when it can be verified at several times, or differences of time, disjunctively or separately. If it supposes with respect to several times conjunctively, it is instead restricted. If I want to verify that some man who is or was is white, it is easier to do so than if I want to verify this of a man who both is and was; therefore the first is amplified across more supposits, while the second is restricted. Although for physicists temporal differences are only three—present, past, and future—in logical ampliation five are considered: present, past, future, possible, and imaginable.

There are SOME RULES by which one can recognize when a term is amplified.

First: In propositions with a past-tense copula, a term preceding the verb is amplified to include what is or was, while a term following it is restricted to what was. Thus in “Peter was white,” Peter can stand for someone who exists now and existed before, or for someone who existed but no longer does; white stands only for past whiteness. Present whiteness is not verified by was, but by is, insofar as it is present, even if it was white at another time. Similarly, if the copula is future, the term preceding the verb is amplified to include what is or will be, while the following term is restricted to what will be, as in “Peter will be white,” “Antichrist will be a sinner.”

Understand, however, that the amplified term preceding the verb must always have existed if the proposition is past, and must be going to exist if it is future; otherwise the proposition would not be verified, because the extremes would not be rightly united. The amplification consists in this: the term stands for something past or future in such a way that, through the same copula, it can also be verified of a present subject, provided it also existed or is going to exist.

Second rule: A term signifying beginning amplifies all terms before and after it to include what is or will be; one signifying cessation amplifies them to include what is or was. For example, “Motion begins to be,” “Motion ceases to be.” The same applies to a term signifying the action of beginning or corrupting, or priority and posteriority. It amplifies the term over which the action of beginning falls to include the present and future, as in “Peter is building a basilica”; or, if it signifies corruption, to include the present and past, as in “Peter is destroying a house.” “House” and “basilica” are amplified to include what is or will be, or what is or was.

Third rule: The verb “can” and the term “possible,” when placed in a proposition, amplify all terms to include possibles, as “A man can be white” is verified also of a possible man and possible whiteness. The same applies to terms signifying aptitude, since aptitude is a kind of possibility. Subjects are amplified to include possibles if aptitude for existing is signified, but not if only aptitude for acting is signified. Thus “Peter is generable or corruptible” amplifies the subject; but “Peter is capable of laughter or understanding” does not, since aptitude for acting presupposes the subject’s existence, although, if it is a proper attribute, it belongs without presupposing existence.

Fourth rule: The term “imaginary” or the verb “is imagined” amplifies all terms preceding and following it to include imaginables, as in “A body is an imaginary chimera.” Likewise, a term signifying an interior act of the mind, such as “I will” or “I understand,” can amplify the term over which it falls as an object, extending it to imaginables. Thus in “Peter understands a chimera,” “chimera” is amplified to include an imaginable thing.

Restriction is a contraction from a greater to a lesser supposition. It can be restriction either with respect to time, as in “Peter, who existed, will not exist,” or with respect to gender, feminine or masculine, as when “Some man is white” is taken only of males or only of females; and finally with respect to supposits through an adjective or a possessive genitive attached to it, for example, “A white man runs,” “A man’s horse does not run.” A possessive genitive restricts just as an adjective does.

Restriction can occur either through an implicative copula, as in “Peter, who is just, is learned,” or through the simple addition of an adjective, as in “Peter the just is learned,” “Peter, who has passed away, will not exist,” “The past Peter will not exist.” Indeed, you will understand especially well how an implicative copula relates the supposits to which it restricts and the time to which it orders them by reducing it to a participle used as an adjective. Thus “Peter, who exists, will exist” is explained as “Existing Peter will exist”; “Antichrist, who does not exist, will exist” as “Nonexisting Antichrist will exist.”

The RULES OF INFERENCE for ampliation and restriction are the same, because what is amplified and unrestricted is the same thing, taken as something higher or more common, while what is not amplified or is restricted is taken as something lower. Six rules are usually given, but they reduce to two, since an inference proceeds in only two ways: from amplified to nonamplified, that is, from higher to lower, or conversely from nonamplified to amplified, that is, from lower to higher.

First rule: Proceeding from amplified to nonamplified, or from unrestricted to restricted (for these are the same), the inference is valid in affirmatives if one proceeds with distribution of the amplified term and posits the existence of the nonamplified term; it is also valid in negatives without positing that existence. But if one proceeds without distributing the amplified or unrestricted term, the inference is never valid, either negatively or affirmatively.¹ We call positing existence the affirmation that some subject exists. Thus if I say, “Every man is white,” I cannot infer “Therefore Peter is white” unless I add “and Peter exists,” which establishes that this individual is given. But if I say, “No man is white,” even without positing existence one may infer “Therefore Peter is not white,” because supposition and existence of the extremes are not required for a negative proposition.

Second rule: From nonamplified to amplified, or from restricted to unrestricted, the inference is valid in the opposite way: in affirmatives, if one proceeds to the amplified term without distributing it, even without positing existence of the nonamplified term; in negatives, if one argues without distributing the amplified term and with positing existence. Thus “Peter disputes; therefore a man disputes” is valid, as is “Peter does not dispute, and Peter exists; therefore some man does not dispute.” Without positing existence, the consequent could be false in the case where only Paul existed in the world and disputed. Then every man would dispute, and the antecedent, “Peter does not dispute,” would be true because Peter does not exist. But if one argues with distribution of the amplified term, the inference is never valid, either affirmatively or negatively, as in “A man disputes; therefore every man disputes,” and “Some man does not dispute; therefore no one disputes.”

Alienation, which others usually call removal, is “the diversion of a term from its proper to an improper signification,” as in “A man is painted,” “Peter is a lion,” that is, in cruelty. Alienation therefore belongs to improper supposition, and the alienating term is placed on the predicate side, since subjects are such as their predicates allow them to be. But when it is placed as an adjective on the subject side, it restricts the subject as something attached to it; it does not alienate it. Thus if you say, “A painted man is an image,” painted does not alienate but restricts the term man and draws it to a less principal meaning.