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Modus ponens
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<p>In <a href="/facts/Propositional_calculus/MNt5v31V">propositional logic</a>, <i>modus ponens</i> , also known as <i>modus ponendo ponens</i> (from <a href="/facts/Latin_language/pM3Kge85">Latin</a> 'mode that by affirming affirms'), implication elimination, or affirming the antecedent, is a <a href="/facts/Deductive_reasoning/HadA1zWS">deductive</a> <a href="/facts/Argument_form/foVBtMX4">argument form</a> and <a href="/facts/Rule_of_inference/QV5NklQ9">rule of inference</a>. It can be summarized as "<i>P</i> <a href="/facts/Material_conditional/hYf4b7AE">implies</a> <i>Q.</i> <i>P</i> is true. Therefore, <i>Q</i> must also be true." </p><p><i>Modus ponens</i> is a mixed <a href="/facts/Hypothetical_syllogism/XMNClcnc">hypothetical syllogism</a> and is closely related to another <a href="/facts/Validity_(logic)/oMGkywGC">valid</a> form of argument, <i><a href="/facts/Modus_tollens/sqf3PTlf">modus tollens</a></i>. Both have apparently similar but invalid forms: <a href="/facts/Affirming_the_consequent/dK0zDWFB">affirming the consequent</a> and <a href="/facts/Denying_the_antecedent/8IPMqqA3">denying the antecedent</a>. <a href="/facts/Constructive_dilemma/86Beulx6">Constructive dilemma</a> is the <a href="/facts/Logical_disjunction/jbI2EGlM">disjunctive</a> version of <i>modus ponens</i>. </p><p>The history of <i>modus ponens</i> goes back to <a href="/facts/Classical_antiquity/JBq8vEX9">antiquity</a>. The first to explicitly describe the argument form <i>modus ponens</i> was <a href="/facts/Theophrastus/YEeQeInW">Theophrastus</a>. It, along with <i><a href="/facts/Modus_tollens/sqf3PTlf">modus tollens</a></i>, is one of the standard patterns of inference that can be applied to derive chains of conclusions that lead to the desired goal. </p>