Logic and Logical Fallacies

Are you guilty of using any of these logical fallacies? Learn more with Professor Steven Novella in Your Deceptive Mind: A Scientific Guide to Critical Thinking Skills.

Two silhouettes of heads with  blocks representing good and bad logic

ad hominem: A logical fallacy in which an assertion is said to be false or unreliable because of an alleged negative attribute of the person making the assertion; arguing against the person rather than the claim itself.
anomaly: A phenomenon that is incompatible with or cannot be explained by current scientific theories.
false continuum: A logical fallacy in which the fact that a characteristic varies along a continuum is used to argue that the extreme ends of the continuum do not exist or cannot be meaningfully identified.
false dichotomy: A logical fallacy in which multiple choices are reduced artificially to only a binary choice, or where a continuum is reduced to its two extremes.
intelligent design: The term used to self-describe a new school of creationism that holds that life is too complex to have arisen from natural processes alone.
paranormal: Any belief or phenomenon that allegedly is outside the naturalistic laws of science.
petitio principii: A Latin term for begging the question, or assuming one’s conclusion in the premise of an argument.
reductio ad absurdum: A Latin term that refers to a legitimate logical argument in which a premise is taken to its logical, although absurd, conclusion. This can be a fallacious argument if the absurd conclusion is forced and does not follow inevitably from the premise.
tautology: In logical terms, this is an argument in which the conclusion
simply repeats the premise and is, therefore, not a true argument.