Logical fallacies are common errors of reasoning. If an argument commits a logical fallacy, then the reasons that it offers don’t prove the argument’s conclusion. (Of course, that doesn’t necessarily mean that the conclusion is false, just that these particular reasons don’t show that it’s true.)

There are literally dozens of logical fallacies (and dozens of fallacy web-sites out there that explain them). For OCR’s Critical Thinking course, the fourteen fallacies below are those that it’s most important to know about (these are the fallacies listed in the course specification).

• Ad Hominem
• Appeal to Authority
• Appeal to History
• Appeal to Popularity
• Circularity
• Confusing Necessary and Sufficient Conditions
• Correlation not Causation
• Inconsistency
• Generalisation
• Restricting the Options
• Slippery Slope
• Straw Man
• Tu Quoque
• Weak Analogy

You need to be able to recognise each of these fallacies, and also to explain what is wrong with arguments that commit them. Once you’ve learned what the fallacies are, pay attention and see if you can spot any of them being committed on TV, the radio, or in the press.

Links

• Brain Yoder’s Fallacy Zoo
• Bruce Thompson’s Fallacy Page
• Charles Ess, Informal Fallacies
• Fallacies: The Dark Side of Debate
• The Fallacy Files
• The Galilean Library Guide to Fallacies
• The Internet Encyclopedia of Philosophy, Fallacy entry
• Logical Fallacies .Info
• Michael LaBossiere’s Fallacies Introduction
• Philosophy.Lander.Edu, Introduction to Logic, Informal Fallacies
• Stephen’s Guide to the Logical Fallacies
• Wheeler’s Logical Fallacies Handlist

Finally, James W. Benham and Thomas J. Marlowe have put together a list showing that being able to explain the fallacies and being able to avoid committing them are two different things.