Methods of Proof

Rules of Inference

  1. Modus ponens or law of detachment
  2. Simplification
  3. Modus tollens
  4. Hypothetical Syllogism
  5. Disjunctive Syllogism


  1. Fallacy of affirming the conclusion
  2. Fallacy of denying the hypothesis
  3. Begging the question or circular reasoning

Methods of Proof of an Implication

Types of Proof

  1. Trivial Proof
  2. Vacuous Proof
  3. Direct Proof