the 14 core formal fallacies definitions

affirming the consequent

assumes that because a specific result happened , the specific result must have caused it. Ignoring the fact that other causes could lead to the same result.

denying the consequent

thinking that if a certain condition didn’t happen, then the result cant happen - even though the result might still happen for other reasons. Basically treating one condition as the only cause

undistributed middle

assumes that two things are related because they both share something in common even though that shared thing doesnt prove any direct connection

illicit major term

this is when the conclusion says something about an entire group, even though that group wasnt talked about in the premises.

illicit minor term

this happens when the conclusion says something general about a specific group that wasnt fully covered or clearly defined in the earlier statements

fallacy of four terms

when a syllogism has four terms instead of three. This happens usually when a word is used with two different meanings breaking logical structure

exclusive disjunction fallacy

assumes that if one option is true then the other must be false even though both can be true at the same time

Quantifier shifter

Wrongly switching the meaning of everyone, someone, something, or everything in a sentence making the argument sound right even though the conclusion is false.

Existential fallacy

Assuming that something exist simply because a rule is stated about it. This is without providing evidence that the thing actually exists

Non sequitur

When a conclusion doesn't logically follow from the information given. Even if the statements sound related

False conversion

Assumes A statement can be flipped around and still be true, even though the original directions matter and the reverse might not be valid

Negative premises fallacy

When the argument is based entirely on negative claims, which leaves no link between the ideas. This results in no basis for a valid conclusion

Negative conclusion from affirmative premises

When someone makes a negative conclusion from only positive statements

Affirmative conclusion from negative premises

When someone draws a positive conclusion from a negative claim. Resulting in a contradiction in the logic