noun
presupposition
pree-sup-uh-ZISH-un/ˌpriːsʌpəˈzɪʃn/
An assumption taken for granted before reasoning or speaking.
Their route planning rests on the presupposition that the bridge connects both banks.

Etymology
The pieces suggest something placed underneath beforehand: an assumption serving as a basis. A presupposition is taken as already established before the reasoning or discussion begins.
In context
i don't think his conclusion was based off of that as a presupposition i think it's a conclusion based off the evidence
More examples
- Asking why he quit carries the presupposition that he quit.
- The budget reflects a presupposition that prices will remain stable.
- Before we debate solutions, let's examine our presuppositions.
Forms
presupposition · presuppositions
presuppose verb — To take something for granted in advance.
Similar words
- assumption
- Broader term for something accepted as true without proof.
- premise
- A starting point for an argument, often explicitly stated.