Appendix:Glossary of logic

This is a glossary of logic.

A

 * antecedent : The conditional part of a hypothetical proposition

C

 * conclusion : In a syllogism, the proposition that follows as a necessary consequence of the premises.


 * consequent : The second half of a hypothetical proposition; Q, if the form of the proposition is "If P, then Q."


 * contraposition : The statement of the form "if not Q then not P", given the statement "if P then Q".

D

 * domain of discourse : In predicate logic, an indication of the relevant set of entities that are being dealt with by quantifiers.

F

 * formula : A syntactic expression of a proposition, built up from quantifiers, logical connectives, variables, relation and operation symbols, and, depending on the type of logic, possibly other operators such as modal, temporal, deontic or epistemic ones.

I

 * implication : The connective in propositional calculus that, when joining two predicates A and B in that order, has the meaning "if A is true, then B is true".


 * inference : The act or process of inferring; the production of a proposition based on given propositions.


 * inverse : A statement constructed from the negatives of the premise and conclusion of some other statement: ~p → ~q is the inverse of p → q.

M

 * material implication : An implication as defined in classical propositional logic, leading to the truth of paradoxes of implication such as Q &rarr; (P &rarr; P), to be read as "any proposition whatsoever is a sufficient condition for a true proposition".


 * modus ponens : A valid form of argument in which the antecedent of a conditional proposition is affirmed, thereby entailing the affirmation of the consequent.

P

 * premise : Either of the first two propositions of a syllogism, from which the conclusion is deduced.


 * proposition : The content of an assertion that may be taken as being true or false and is considered abstractly without reference to the linguistic sentence that constitutes the assertion.

R

 * reductio ad absurdum : The method of proving a statement by assuming the statement is false and, with that assumption, arriving at a blatant contradiction.

S

 * sentence : A formula with no free variables.


 * syllogism : An inference in which one proposition (the conclusion) follows necessarily from two other propositions, known as the premises.