The study of the principles of reasoning. One of the arts in the medieval trivium.
- Informal Logic
- Logical Proof
- Renaissance Rhetoric
Etymology:From the Greek, "reason"
- "But of all the arts the first and most general is logic, next grammar, and finally rhetoric, since there can be much use of reason without speech, but no use of speech without reason. We gave the second place to grammar because correct speech can be unadorned; but it can hardly be adorned before it is correct."
(John Milton, The Art of Logic, 1672)
- "Logic is the armory of reason, furnished with all defensive and offensive weapons. There are syllogisms, long swords; enthymemes, short daggers; dilemmas, two-edged swords that cut on both sides; sorites, chain-shot."
(Thomas Fuller, "The General Artist," 1661)
- "Some logicians study only formal logic; that is, they work only with abstract models that have purely logical substance and content. . . .
"Relating the abstract systems of formal logic to 'real' statements and arguments is not part of formal logic itself; it requires the consideration of many issues and factors beyond the basic logical forms of the statements and arguments. The study of the factors other than logical form relevant to the analysis and evaluation of statements and arguments of the kind that occur in everyday situations is known as informal logic. This study includes considerations of such things as: identification and clarification of vague or ambiguous statements; identification of unstated assumptions, presuppositions or biases and making them explicit; recognition of frequently used but highly questionable premises; and assessment of the strength of analogies between more or less similar cases."
(Robert Baum, Logic, 4th edition, Harcourt Brace, 1996)