Sufficient and Necessary Assumptions

[Kmikaeli]

After reading about both these ideas I want to make sure I have the right mindset when thinking about them.

Necessary Assumptions are those that must be true in order for the argument/conclusion to be held true. They are the exact unstated premise that is require in order to bridge the premise and conclusion together.

Sufficient Assumptions are those types of assumptions (Justify) that require you to determine an assumption that is sufficient enough to allow the conclusion to be at 100 percent. They can consist of a necessary assumption or include a lot of extra info or "enough" info and etc in order to prove the conclusion to be valid.


Both revolve around a mechanistic approach (Assumptions and Justify the Conclusion) but Assumption questions are necessary based while Justify are sufficient based.

[Jon Denning]

That's the exact right idea, yes! We don't categorize them with that language (sufficient vs necessary assumptions) typically, calling them instead Justify (sufficient) and Assumption (necessary), but the functionality is as you describe it.

I'd be a little bit wary of expecting all of them to be perfectly mechanistic though, where pieces are "missing" and it all fits together like a math equation, or jigsaw puzzle. That's certainly true for a lot of Assumption (particularly Supporter Assumptions) and Justify, but may not always be the case, especially when dealing with Defender Assumptions. Defenders simply refute a potential objection or point of harm to the argument, so they are often harder to predict and less purely mechanistic than other types.

In any case, you're thinking about these in the correct way, so well done!