Critical Thinking: The Forgotten Discipline

A stack of 3-by-5 index cards sits on my desk next to my computer keyboard. Thirty-six of them, give or take a few. On the front of each index card is written the name of a particular type of logical fallacy; on the back is written its definition. All of the names and definitions are from this site. It's not an exhaustive list, but it's large enough to capture the flavor of the most commonly encountered types of logical fallacies. Here are the three main categories under which my index cards are organized:

1. Fallacies of Ambiguity: Appear to support their conclusion only due to their imprecise use of language (Examples: Accent fallacy, equivocation)
2. Fallacies of Presumption: Do not contain any logical reasoning errors, but begin with a false (or at least unwarranted) assumption and so fail to establish their conclusion (Examples: False dilemma, complex question, circular reasoning)
   
3. Fallacies of Relevance: Attempt to support their conclusion by offering considerations that simply don't bear on its truth (Examples: Ad hominem, genetic fallacy, appeal to authority, appeal to popularity)
   

The index cards are always sitting here right where I can see them, because I need a constant reminder that I should always try to be in a critical state of mind whenever reading or writing. But I often forget. Critical thinking and logical argumentation are disciplines, and discipline is hard. It is dangerously easy to be persuaded by slick and artfully worded, but ultimately fallacious, arguments if one is not continuously on the lookout for cracks in their logic. And it is just as easy to write fallacies without realizing it. I do it quite often. But I'm trying to learn and improve as I go along, and these index cards on my desk help me to do that.

For an entertaining collection of real-world examples of various logical fallacies, complete with source citations, check out the Fallacy Files. Once you familiarize yourself with the most common fallacies, you will start to notice them everywhere -- maybe even occasionally in the works of some of the world's brightest thinkers.

What better way to defend one's liberty than to train oneself to recognize and refute fallacious arguments used to attack it?