eristic the art of controversy, often involving fallacious but persuasive reasoning. The ancient Sophists brought this art to a high level to achieve their personal goal. They may have found their material in the ‘encounters’ in the law courts as well as in daily life. To enhance persuasion they endorsed the use of unsound principles such as hasty generalizations, faulty analogies, illegitimate appeal to authority, the post hoc ergo propter hoc (i.e., ‘after this, therefore because of this’) and other presumed principles. Aristotle exposed eristic argumentation in his Sophistical Refutations, which itself draws examples from Plato’s Euthydemus. From this latter work comes the famous example: ‘That dog is a father and that dog is his, therefore that dog is his father’. What is perhaps worse than its obvious invalidity is that the argument is superficially similar to a sound argument such as ‘This is a table and this is brown, therefore this is a brown table’. In the Sophistical Refutations Aristotle undertakes to find procedures for detection of bad arguments and to propose rules for constructing sound arguments. See also DIALEC- TIC , INFORMAL FALLACY , SYLLOGIS. I.Bo.