Logical Fallacies

Overview

A fallacy is an argument that looks like it works but doesn't. The test is not whether the conclusion is true — it's whether the inference from premises to conclusion is valid. This skill covers two layers: the classical taxonomy (Aristotle's 13, c. 350 BCE — verbal and structural errors) and the modern cognitive map (Tversky-Kahneman 1983 — errors competent reasoners commit automatically before any sophist arrives).

Composes with neighbors: critical-thinking audits evidence quality and framing; first-principles attacks premises; mece catches decomposition errors that masquerade as false-dichotomy or composition fallacies.

When to Use

• An argument feels persuasive but you cannot articulate why
• A claim is supported entirely by authority, popularity, emotion, or anecdote
• You're about to decide based on a single argument or analogy
• A debate is moving fast ("everyone knows Y") — speed is the sophist's friend
• You catch yourself reasoning emotionally ("this has to be true because…")
• You're weighing an AI hype or AI-adoption claim ("a lab CEO said it's near," "it passed the benchmark so it's intelligent," "doom vs. utopia")

When NOT to use: casual small talk with low stakes; conclusion is empirically verifiable (just check the data); you're tempted to name a fallacy to dismiss an opponent rather than find truth (that is itself the fallacy fallacy).