in logic, erroneous reasoning that has the appearance of soundness. Among numerous types of logical fallacies that have been noted, some of the better known are: post hoc ergo propter hoc (“after this, therefore, because of this”), in which something is assumed to be the cause of something else merely because it was antecedent in time; ad hominem (“against the man”), attacking an individual rather than establishing pertinent facts; and circulus in probando (“arguing in a circle”; also called petitio principii, “begging the question”), attempting to demonstrate a conclusion by means of premises that presuppose that conclusion.
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