Premise

A premise or premiss is a <a href="/facts/Proposition/0877MFMD">proposition</a>—a true or false declarative statement—used in an <a href="/facts/Argument/1K1e3Xg4">argument</a> to prove the truth of another proposition called the <a href="/facts/Logical_consequence/AyDXp4dn">conclusion</a>. Arguments consist of a <a href="/facts/Set_(mathematics)/BfucfHMq">set</a> of premises and a conclusion.
An argument is meaningful for its conclusion only when all of its premises are <a href="/facts/Truth/NyQmBtUC">true</a>. If one or more premises are false, the argument says nothing about whether the conclusion is true or false. For instance, a false premise on its own does not justify rejecting an argument's conclusion; to assume otherwise is a <a href="/facts/Logical_fallacy/1c3P1BEH">logical fallacy</a> called <a href="/facts/Denying_the_antecedent/8IPMqqA3">denying the antecedent</a>. One way to prove that a proposition is false is to formulate a <a href="/facts/Soundness/ndpamd2A">sound</a> argument with a conclusion that <a href="/facts/Negation/q5AQBvBj">negates</a> that proposition.
An argument is <a href="/facts/Soundness/ndpamd2A">sound</a> and its conclusion logically follows (it is true) <a href="/facts/If_and_only_if/bYSxGJ66">if and only if</a> the argument is <a href="/facts/Validity_(logic)/oMGkywGC">valid</a> and its premises are true.
An argument is <a href="/facts/Validity_(logic)/oMGkywGC">valid</a> if and only if it is the case that whenever the premises are all true, the conclusion must also be true. If there <a href="/facts/Existential_quantification/hHveaBYo">exists</a> a <a href="/facts/Interpretation_(logic)/goPmjjQG">logical interpretation</a> where the premises are all true but the conclusion is false, the argument is invalid.
Key to evaluating the quality of an argument is determining if it is valid and sound. That is, whether its premises are true and whether their truth <a href="/facts/Logical_truth/N0bUYhUW">necessarily</a> results in a true conclusion.

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Premise