

Sample sentences AND operator IF/THEN operator NOT operator OR operator XOR operator Chain Rule Conjunctive Addition Contrapositive DeMorgan's Law Disjunctive Addition Disjunctive Inference Disjunctive Infer. (XOR) Double Negation Modus Ponens Modus Tollens Mutual Exclusion Simplification 2step 3step 4step 5step or more Bad Argument 
Modus Ponens Modus Ponens is a rule of inference pertaining to the IF/THEN operator. Modus Ponens states that if the antecedent of a conditional is true, then the consequent must also be true. Imagine we have the following conditional sentence: "If it is raining, then there are clouds in the sky." Formally, we would write: p > q: "If it is raining, then there are clouds in
the sky." In this expression, "If it is raining" is the antecedent and "There are clouds in the sky" is the consequent. Now if we know for a fact that it is raining, then we have to conclude that there are clouds in the sky. If the antecedent ("It is raining") is true, then the consequent ("There are clouds in the sky") must also be true, by Modus Ponens. Let's write our steps formally: p > q: "If it is raining, then there are clouds in
the sky." The conditional p > q and the given p are above the line of dashes, and the conclusion q obtained by applying Modus Ponens is below the line.
Other examples of Modus Ponens W > C: If Yankees win today's game, they will be champions.
W > B: If the weather is good, we can go to the beach.
Links to Relevant Problems These are links to validity proof problems whose solutions contain Modus Ponens. 2step problem (A)
