Overview

Fallacies are defects in an argument—other than false premises—that cause the argument to be invalid, unsound, or weak. Identifying fallacies is a crucial skill in critical thinking and debate.

Core Idea

The core idea is that bad arguments often look like good arguments. Fallacies are deceptive patterns of reasoning that can be persuasive psychologically even if they are logically flawed.

Formal Definition

A fallacy is a failure in reasoning that renders an argument invalid. They are often categorized into formal fallacies (structural errors in deductive logic) and informal fallacies (errors in content or context).

Intuition

A fallacy is a glitch in the matrix of reason. It’s a shortcut that leads to a wrong destination. Like a magician’s trick, it misdirects attention from the actual evidence to something irrelevant (emotion, authority, personal attacks).

Examples

  • Ad Hominem: Attacking the person instead of the argument. (“You’re wrong because you’re ugly.”)
  • Straw Man: Misrepresenting an opponent’s argument to make it easier to attack. (“My opponent hates freedom because he wants to regulate pollution.”)
  • Circular Reasoning (Begging the Question): Assuming the conclusion in the premise. (“The Bible is true because it says it is true.”)
  • Slippery Slope: Arguing that a small step will inevitably lead to a chain of terrible events.

Common Misconceptions

  • Misconception: If an argument contains a fallacy, the conclusion must be false.
    • Correction: This is the “Fallacy Fallacy.” A bad argument can still happen to have a true conclusion (by luck).
  • Misconception: Being rude is an Ad Hominem.
    • Correction: An insult is just an insult. It becomes a fallacy only if used as evidence to disprove a claim.
  • Cognitive Bias: Systematic patterns of deviation from norm or rationality in judgment (the psychological root of many fallacies).
  • Validity: The property of an argument where the conclusion logically follows from the premises.
  • Rhetoric: The art of persuasion, which often employs fallacies effectively.

Applications

  • Debate: Spotting flaws in opponents’ arguments.
  • Media Literacy: Recognizing manipulation in advertising and politics.
  • Science: Avoiding errors in data interpretation (e.g., correlation vs. causation).

Criticism and Limitations

  • Ambiguity: Some “fallacies” (like Appeal to Authority) can be reasonable heuristics in certain contexts (trusting a doctor on medical advice).

Further Reading

  • Attacking Faulty Reasoning by T. Edward Damer
  • Thinking, Fast and Slow by Daniel Kahneman