Formal Fallacies, Informal Fallacies
A logical fallacy is a mistake in reasoning. The premises of good arguments support the conclusion, so that in the case of deductive arguments, if the premises are true, the conclusion must also be true. In the case of inductive arguments, true premises make the conclusion more likely. Deductively valid argument forms can be defined as those in which true premises never lead to a false conclusion, no matter what content is presented in that form. In logic, arguments and argument forms are studied and a system of rules is created to systematically distinguish between valid and invalid arguments. Invalid argument types that appear frequently and that seem to be especially deceptive have been categorized and given names. The study of logic and the naming of logical fallacies began with Aristotle (384–322 B.C.E.), and standard Latin names of fallacies have been inherited from the Middle Ages, so "logical fallacy" is not a concept that has changed much with time. However, the teaching of logical fallacies has been revived with the popularity of courses entitled "critical thinking" rather than "logic'" in order to highlight their emphasis on natural language and informal fallacies, rather than on formal logical systems.