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III — Logic & Argument

Validity, soundness, and the fallacy field guide

Deduction, induction, abduction, and the recurring shapes of broken reasoning.

Epistemic status · Well Established

Three engines of inference

Deduction guarantees the conclusion if the premises hold. Induction generalises from cases and can always be overturned. Abduction picks the best available explanation — and is only as good as the alternatives you bothered to consider.

Valid is not the same as true

An argument can be perfectly valid and entirely false, if a premise is false. Check structure and content separately.

Fallacies are attractors

Ad hominem, straw man, false dilemma, appeal to authority, appeal to nature, circular reasoning, moving goalposts, No True Scotsman. They persist because each one feels persuasive from the inside.

Practice

Steelman a position you reject until someone holding it would agree with your version.

TEST A BELIEF

Next

Your reasoning has a systematic tilt