A fallacy is an adaptation that makes an argument seem true without necessarily being so.

Considering that reasoning can fail in countless ways, fallacies are classified as formal (an attempt at valid deductive reasoning, without being so) and informal (any other error).

Some formal fallacies

• Ad Hominem: An irrelevant attack on the arguer, such as pointing out a personal characteristic unrelated to the argument, suggesting that this attack weakens the argument itself.

• Appeal to Authority: Assuming that something is true or right just because an authority figure supports it.

• Bandwagon Appeal: Assuming that something is true or right simply because many people believe or do it.

• Circular Reasoning: When the conclusion of an argument is assumed within its premises.

• False Dilemma: When an argument presents only two options, ignoring other possibilities that might exist.

• Hasty Generalisation: Drawing a conclusion based on insufficient or unrepresentative evidence.

• Red Herring: Diverting attention from the main issue by introducing an irrelevant topic.

• Slippery Slope: Assuming, without evidence, that a specific action will inevitably lead to a chain of undesirable events.

• Straw Man: Misrepresenting an argument by exaggerating or distorting it.

• Post Hoc Ergo Propter Hoc (False Cause): Assuming that when one event occurs after another, the first must have caused the second.

Some informal fallacies

• Mind Projection: Assuming that the way one sees the world reflects the way the world actually is.

• Relative Privation: Assuming that if something is worse than the problem currently being discussed, then the problem currently being discussed is not that important.

• Typical Mind: Assuming that other people are more like us than they actually are.