Now coming to your "further-explanation"

Testluv wrote:if the opposite of a fact (ie, a denied answer choice) strengthens, then the fact itself (ie, original answer choice) is a weakener.

always?

Consider this argument:

A person who can write a computer program knows how to use a computer. Therefore, X knows how to use a computer.

and one of the answer choice said:

> X was seen writing a computer program this afternoon.

I agree that this option would definitely strengthen the argument. But, did you mean its negation : " X was not seen writing a computer program this afternoon" weakens the argument. How ?

OR :

I sit at home when it rains. Hence, on Friday at 8:00 AM it was raining.

one of the option said :

> I was watching a movie on Friday at 8:00 AM in my house.

a "strengthener" for the case in hand. But is the negation a weakener?


As far as I know, if P IMPLIES Q, NOT P does not necessarily IMPLY NOT Q. This comes from the principles of Discrete Maths.

Again, please correct me if I'm wrong somewhere in my reasoning.

Testluv wrote:As a matter of strategy, using denial test is often helpful in strengthen question's answer choices that use negative language such as "not"; in these cases, it is often easier to see what impact a denied fact will have on the argument (as opposed to the original fact.)

I know you said "often" above, but further conditions to apply negation technique should be metioned as well. The negation technique works when the strengthener/weakener is an assumption. Again, I will take help from Discrete Maths & Logic principles.


Consider an argument which has a premise P, an assumption Q and a conclusion R. Birds eye view of this argument :

P together with Q implies R.

or according to the author, R hold true when P and Q each hold true.


in Logic principles it is P AND Q => R.

when the conclusion holds true, R is 1. For this to be true, P and Q each has to be 1 . i.e 1 AND 1 = 1 or P and Q each should be true. ( in sync with our normal english)

(binary value 1 means occurrence and 0 means non-occurrence)


when we negate the assumption Q, we basically make the value of Q as 0. And when we multiply P (1) with Q (0), R becomes 0.

You normally call this " the conclusion falls apart". Hence, we conclude Q is a necessary assumption. Hence, when finding a necessary assumption or a strengthener/weakener, which is an assumption, negation technique works.

But, in the cases mentioned above, where the option just supports from outside and is not an assumption, negation technique won't help. That is what happened in the examples above.


Hope you agree with me!