(Latin: "method of affirming" and "method of denying") In logic , two types of inference that can be drawn using a hypothetical proposition
i.
e., from a proposition of the form "If p, then q" (symbolically p 2283; q). Modus ponens refers to inferences of the form p 2283; q; p, therefore q. Modus tollens refers to inferences of the form p 2283; q; 00AC; q, therefore, 00AC; p. An example of modus tollens is the following: "If an angle is inscribed in a semicircle, then it is a right angle; this angle is not a right angle; therefore, this angle is not inscribed in a semicircle."