PrezRand wrote:Both. Sometimes I can't tell the difference.
It can be weird because sometimes based on the argument, the assumption could be both. But the way to think about it is as follows:
Necessary assumption is required. Question stems are what is an assumption that it requires, what is a presumption necessary, the argument relies on what?
All mammals have brown fur
Dogs are on the island
All dogs on the island have brown fur
dogs are mammals (duh)
But say I swapped the word fish for dogs. You would have to assume that fish are mammals, even though that's not right scientifically, to get to the conclusion with the evidence I give you. If you don't and fish are not mammals then my conclusion doesn't work which breaks the argument via negation proving that you have to assume that fish are mammals
Sufficient is basically proves the conclusion.
From a larger perspective, consider the following two sentences:
1. Attending my lecture is sufficient for you to get an A in class. Literally by going to the lecture you get an A
2. Attending the lecture is required to get an A. In this second sentence, just going to the lecture doesn't give you an A so it's not sufficient to getting an A but you have to do it if you want that A.
That's how I think of sufficient assumptions. They have to be like #1
Henry took his clothes off
Henry was hot
A sufficient assumption would be if someone takes their clothes off they're hot or the contrapositive of if someone is not hot then they don't take their clothes off.
The wrong assumption would be if they're hot they take off their clothes because it's on the wrong side of the arrow for conditional reasoning.