Syllogism. In traditional logic a syllogism is a form of reasoning by deductive inference; e.g., given two propositions such as "All Frenchmen understand French; this man is a Frenchman; therefore he must understand French." This is a valid argument. The conclusion is not necessarily true; its truth depends on the premises. What a syllogism shows is the validity or invalidity of the argument. The form just given is that of the categorical syllogism in which there are two premises and a conclusion, each with a subject and predicate. There are, however, other forms of deductive inference, e.g., the hypothetical syllogism. Common forms are as follows: (1) "If the car battery is dead, we cannot go to the party; the car battery is dead; therefore we cannot go to the party." (This type is called Affirming the Antecedent.) (2) "If I had had an aptitude for languages I could have passed this German test; I cannot pass this German test; therefore I have not a facility for languages." (This type is called Denying the Consequent.) Another very common syllogistic form is the disjunctive syllogism, of which there are two kinds: weak and strong. E.g., "Either the candidate is stupid or else he is wicked; he is not wicked; therefore he must be stupid." One could decline, however to accept the second disjunct; then one could go on to conclude that the candidate is both stupid and wicked, for possession of the one quality does not exclude possession of the other. This is called a weak disjunction. If, however, one proposed a disjunctive syllogism in the following form, one could not so proceed. This is called a strong disjunction: "Either the candidate was born in Boston or he was born in Los Angeles; he was not born in Boston; therefore he was born in Los Angeles." The candidate, as we have seen, could be both wicked and stupid, but he could not have been born both in Los Angeles and in Boston.

Deductive inference in analytical, i.e., it does not yield new knowledge. What it does is to exhibit the implicates of what is already known. The examples given here are of course extremely simple ones, but the principle is the same however simple or complex the argument may be.

Geddes MacGregor, Dictionary of Religion and Philosophy, New York: Paragon House, 1989

syllogism : (m.) tidhābhūta-takka.

A.P. Buddhadatta Mahathera, Concise Pali-English and English-Pali Dictionary [available as digital version from Metta Net, Sri Lanka]