What is a premise?

Premise is each of the statements that support the conclusion of an argument. It's the foundation: if the premise falls, what was built on it falls with it, no matter how good the construction.

The classic example

In the two thousand year old syllogism, all men are mortal; Socrates is a man; therefore, Socrates is mortal, the first two sentences are the premises, and the third is the conclusion they support. Note that the conclusion is only guaranteed because the premises, together, already contained the necessary information to reach it.

Why the premise decides the argument

A false premise contaminates all subsequent reasoning, even when the logical structure is impeccable. It is the case that all fish fly; salmon is fish; therefore, the salmon flies: the form of the argument is valid, but the first premise is false, and therefore the conclusion is absurd.

Therefore, before accepting any conclusion, the first question to ask is not "does this sound logical?", it is "are the premises really true?". That's where most twisted reasoning hides the problem: not in the structure, in the base.

Premise is not opinion

It is worth noting the difference between premise and loose opinion. A premise enters an argument to be examined, questioned and, if necessary, overturned with reasons. When someone presents a claim as if it were too obvious to check, this is precisely the time to ask whether it really is a solid premise or a false assumption. fallacy disguised as data.

To see the premise in action within the full structure of the argument, see how it articulates with the conclusion in premises, conclusion and validity.

Readings from Nous

Read the classics in depth

Our list of more than 130 recommended books, commented and organized by theme, so you don't read in the dark.