Here are a bunch of logical fallacies, or common errors in thinking and argumentation. Some of them I made up, and some of them have been known for a long time.
- Affirming the consequent – This is a way of distorting if and then statements. For example, the statement “If it rains, I won’t go out,” means that I’ll go out only if it doesn’t rain. It does not mean, “If it doesn’t rain, I will go out.” It’s possible that it doesn’t rain, but I still don’t go out.
- Cum hoc ergo propter hoc – Two things that correlate are not necessarily causally related. For example, suppose that kids who play video games are more likely to be violent. But this does not mean that video games cause violence. Perhaps violent people are more likely than non-violent people to like video games. Or maybe there is a factor that causes both violence and love of video games.
- Fiction equals fact – This is when someone simply makes up facts and provides absolutely no evidence to support them. This shouldn’t even be listed as a fallacy, but I have seen many people do it. Stating random, false propositions as if they are fact is a terrible argumentative tactic but, if you sound sure enough of yourself, fools many people.
- Hypocrisy – This occurs when person A criticizes person B for doing something that person A does himself or herself, or even worse, that person A does but on an even more severe level. For example, person A criticizes person B for eating candy, even though person A eats Twinkies all the time.
- Naturalistic fallacy – This is one of the most common fallacies I have seen people make. It involves inferring normative statements (statements about what should be) from descriptive statements (statements about what is). It often takes the form of assuming that because something is common or popular, it is good. For example, everyone at school, including honors students, wears short skirts. Therefore it is okay to wear a short skirt. Or, most people in Europe disrespect America. Therefore, America is bad. These inferences are completely false because their conclusions contain normative claims, while their premises contain only descriptive claims. These are two completely different realms of claims, and it is impossible to get from one to the other.
- Relative equals absolute – This fallacy occurs when someone equates a thing having more of a property with that thing having the property in the absolute sense. For example, coat A is warmer than coat B. Therefore, coat A is warm and coat B is not warm. This is completely false; perhaps neither coat is warm, but A is closer to being warm than B, or perhaps both coats are warm, and A is just warmer than B.
- Straw man – The straw man fallacy occurs when somebody exaggerates their opponent’s position, refutes the exaggerated position, and says that they’ve refuted their opponent. For example, person A is in favor of increasing the rigor of background checks that people have to undergo in order to purchase a gun. Person B is not. Person A argues that it would be terrible if criminals and lunatics were allowed to have guns, and claims to have refuted person B’s position.