Logical Fallacies

Syllogism (not a fallacy)

A logical argument presented in terms of two statements and a conclusion which must be true if the two statements are true.

EX: A-Mammals are warm blooded. B-Dogs are mammals. C-Therefore, dogs are warm blooded.

Syllogisms continued

Major Premise: A-Mammals are warm blooded.

Minor Premise: B-Dogs are mammals. Conclusion: C-Therefore, dogs are warm

blooded.

Logical Fallacies

Fallacies are statements that resemble a logical argument but are actually flawed.

They are often persuasive, but they (unfairly) manipulate the audience in order to win agreement.

An error of reasoning based on faulty use of evidence or incorrect inference.

“Begging the Question”

Making a statement that assumes that the issue being argued has already been decided.

Ad Hominem (“Against the Man”) Attacks

Simply put, these are personal attacks. Attacking the arguer rather than the

argument.

Hasty or Sweeping Generalization

Drawing conclusion from insufficient evidence, or applying a conclusion too broadly.

False Dilemmas

Also known as the Either/Or Fallacy. Simplifying a complex problem into an

either/or dichotomy.

Red Herring

When an irrelevant topic is presented in order to divert attention from the main topic being argued.

“Changing the subject”

“You Also” (Tu Quoque)

A logical fallacy that tries to discredit an argument by asserting that since the arguer does not abide by their argument, the argument is invalidated.

A presents argument x A does not abide by argument x. Therefore, x is not true. A type of ad hominem.

Post Hoc Reasoning

A logical fallacy that involves looking back at two events that occurred in chronological order and wrongly assuming that the first event caused the second.

Non Sequiturs

“It does not follow” Using irrelevant premises to buttress a

conclusion. The conclusion does not logically follow from

the premises.

Distorting Statistics

It is what it sounds like.

Faulty Use of Authority

Failing to acknowledge disagreement among experts or otherwise misrepresenting the trustworthiness of sources.

Straw Man Argument

Disputing a view similar to, but not the same as, the view of one’s opponent.

Misrepresenting the other argument, attacking that misrepresented argument, and thinking you have attacked the real argument.

Attacking a weak defender of an argument and acting as if the entire argument has been defeated.