If you have discussions with any type of science denier, you will begin to notice that they will shift the argument away from evidence to using a logical fallacy. It’s frustrating because you want to discuss the evidence, but the denier tries to do anything but discuss that evidence.

That’s why I created this list of the top logical fallacies that I see used frequently in discussions with any science denier, from anti-vaxxers to creationists. I will add additional logical fallacies as I notice them in future discussions.

What is a logical fallacy?

A logical fallacy is essentially an error of reasoning in making an argument. When logically fallacious arguments are used, usually based on bad reasoning to support a position (or to try to convince someone to adopt the same position), it is considered a fallacy.

This means that an argument that uses a logical fallacy shouldn’t hold up to those using logic and reason as the source of decision-making. Of course, it generally doesn’t stop people, specifically those pushing pseudoscience or an anti-science point of view, from using them or being swayed by them.

There are two forms of logical fallacy:

• Formal–These logical fallacies are those fallacies that violate a particular rule of logic. They almost always include non-sequitur logic, that is, the conclusion is not connected to the argument.
• Informal– arguments that, while not violating logic rules, are invalid because of the content of their argument. Informal fallacies are often characterized by the fact that there is a disconnect of some kind between their premises and conclusions.

Deciding between formal and informal logical fallacies is interesting for logic geeks, but I didn’t want to spend time separating between the two. The net effect of either type of logical fallacy is the same – the arguments can be dismissed because of lack of evidence.

List of logical fallacies

Below is a list of the most common fallacies that are used by those who push pseudoscience or deny science – it’s not all-inclusive, so I’m missing a bunch, although I’ll add them if I notice that it is becoming popular with the science-denying crowd:

• Appeal to Antiquity or Tradition 
• Appeal to Popular Belief 
• Appeal to Consequences 
• Appeal to Nature 
• Appeal to Novelty 
• Argument from Fallacy 
• Argument from False or Misleading Authority 
• Argument from Ignorance
• Argumentum Ad Hominem 
• Bandwagon Fallacy 
• Cherry Picking or Quote Mining 
• Confirmation Bias 
• Fallacy of Composition 
• Fallacy of Division 
• False Dichotomy 
• False Equivalence 
• Fundamental Attribution Error (or Correspondence Bias) 
• Galileo Gambit 
• Gambler’s Fallacy 
• Genetic Fallacy 
• Gish Gallop 
• Godwin’s Law
• Naturalistic Fallacy 
• Nirvana Fallacy 
• Non Sequitur 
• Poisoning the Well 
• Post hoc ergo propter hoc 
• Precautionary principle
• Red herring
• Shill Gambit 
• Slippery Slope Fallacy 
• Special Pleading 
• Strawman Argument

Not all of this list are technically logical fallacies. For example, confirmation bias is really a cognitive bias, not a logical fallacy. However, for reference purposes, I include it because it forms the basis of logical fallacies like “cherry-picking.”

For example, confirmation bias, the gambler’s fallacy, and bandwagon fallacies are fallacious not because they violate logic, but because they represent ways in which our natural view of the world may lead us to fallacious conclusions.

Summary

I think that there’s one basic point about a logical fallacy — they are always employed to shift the discussion away from the lack of evidence supporting their claim. Once I notice a logical fallacy, I know the science denier doesn’t have one femtogram (that’s 0.000000000000001 grams) of evidence.

Oh, one more thing. I’ve noticed that the science-denying crowd, especially our favorite anti-vaccine activists, love to try to accuse us of using a logical fallacy, which is always amusing. I think that’s a fallacy in itself.

If you think I need to add another fallacy to this list, please do not hesitate to drop a comment. I don’t mind writing another page or two on logical fallacies.