 The first division in Copi’s classification is between formal and informal fallacies. Formal fallacies are invalid inferences which “bear a superficial resemblance” to valid forms of inference, so these we may think of as deductive fallacies. They include affirming the consequent, denying the antecedent, the fallacy of four terms, undistributed middle, and illicit major. Informal fallacies are not characterized as resembling formally valid arguments; they gain their allure some other way. One division of informal fallacies is the fallacies of relevance which are “errors in reasoning into which we may fall because of carelessness and inattention to our subject matter” (1961, 53). This large class of fallacies includes accident, converse accident, false cause, petitio principii, complex question, ignoratio elenchi, ad baculum, ad hominem abusive, ad hominem circumstantial, ad ignorantiam, ad misericordiam, ad populum, and ad verecundiam. The other division of informal fallacies is called fallacies of ambiguity and it includes equivocation, amphiboly, accent, composition and division.