Logic

The study of the methods and principles used to distinguish correct from incorrect reasoning.

A statement; what is typically asserted using a declarative sentence, and hence always either true or false -- although its truth or falsity may be unknown.

A proposition; what is typically asserted by a declarative sentence, but not the sentence itself. Every statement must be either true or false, although the truth or falsity of a given statement may be unknown.

A process by which one proposition is arrived at and affirmed on the basis of some other proposition or propositions.

Any group of propositions of which one is claimed to follow from the others, which are regarded as providing support or grounds for the truth of that one.

In any argument, the proposition to which the other propositions in the argument are claimed to give support, or for which they are given as reasons.

In an argument, the propositions upon which inference is based; the propositions that are claimed to provide grounds or reasons for the conclusion.

A word or phrase (such as "therefore" or "thus") appearing in an argument and usually indicating that what follows it is the conclusion of that argument.

In an argument,, a word or phrase (like "because" and "since") that normally signals that what follows it are statements serving as premises.

An utterance used to make a statement, but which, because it is in interrogative form and is therefore neither true nor false, does not literally assert anything.

An argument that is stated incompletely, the unstated part of it being taken for granted.

A characteristic of any deductive argument whose premises, if they were all true, would provide conclusive grounds for the truth of its conclusion. Such an argument is said to be valid. Validity is a formal characteristic; it applies only to arguments, as distinguished from truth, which applies to propositions.

One of the two major types of argument traditionally distinguished, the other being the inductive argument. A deductive argument claims to provide conclusive grounds for its conclusion. If it does provide such grounds, it is valid; if it does not, it is invalid.

One of the two major types of argument traditionally distinguished, the other being the deductive argument. An inductive argument claims that its premises give only some degree of probability, but not certainty, to its conclusion.