Cogito ergo sum

Key articles

Logical fallacy Syllogism Argument

General logic

Point refuted a thousand times Slippery slope Suppressed correlative Whataboutism Argument from silence Conditional fallacy

Bad logic

Non sequitur Enthymeme Sanctioning the devil Ad hoc Conspiracy theory Post hoc, ergo propter hoc (português) v -t -e

Anargument from omniscience (alsoallness,absolute thinking) occurs when somebody thinks theyknowliterally everything or know everything about the subject at hand.^[1] The fallacy is commonly expressed with words like "all", "everyone", "no one", "everything", "always", or "never".

The problem with such an argument is twofold: first, that an arguer would need omniscience to know about everyone's beliefs or about everything in existence, and second, because the arguer doesnot have omniscience, they are often wrong and counterexamples to the generalization exist.

The argument is aninformal fallacy and is theoretically the opposite of anargument from ignorance; however, because it relies on things that the speaker cannot know, it functions as an argument from ignorance and fails for the same reasons.

This fallacious form of reasoning often comes in two fantastically fallacious flavours — Alleged Certainty^[2] and Amazing Familiarity.^[3] In the case ofAlleged Certainty, a claim is primed with language, such as "every", "everyone knows", and "we all know", that suggests that something is certainly the case, without providing a solid reason or evidence. This allows them to exploit the supposed obviousness of their point, as the audience, not wanting to feel like they've ignored the obvious, are convinced to agree. It is similar to theAppeal to popularity.

Amazing Familiarity occurs when a claim is made about someone or something, but the information necessary to support this claim is impossible to obtain or would require omniscience on the part of the speaker. This overlaps withwishful thinking, as the claim will often involveprojections on the part of the speaker.

Examples[edit]

An important example is that ofoverprecision.

• Everyone knows that.^[4]

• All people believe in something.^[4]

• All students love studying.^[5]

• The president is a good man and would have never cheated on his wife, and has never cheated in anything in the past.^[6]

In the first three examples, there may be people whodon't — and unless the arguer can prove that no such people exist, then their argument is flawed. In the fourth, the speaker would have to be extremely close to the President — and watched him for almost his whole life — to be able to defend this point.

See also[edit]

• No true Scotsman

References[edit]

• Logic
• Fallacies
• Arguments from ignorance
• Informal fallacies

• Pages using DynamicPageList parser function