Assumption Queations

[dlddls37]

Hello,

I have a question regarding Assumptions (Necessary Assumption).
From the Powerscore article, it defines the assumption as "unstated a premise that must be true in order for the argument to be true".
Compared to the Justify answer which completely proves or guarantees the conclusion, what would be the possible range for assumption answers? I see it does not guarantees the conclusion as Justify answer does (except when I have conditional argument - when the assumption answer inevitably proves the conclusion logically)but just like giving an argument a chance of being valid.

Further, when I see the stimulus for Assumption questions, arguments typically seem to have a reasoning flaw, which means it's an invalid argument. Justify answer completely fill this gap and make the argument 100% valid. In this sense, I don't exactly understand how the assumption answer be what must be true in order for the argument to be true/valid. Do I have to think assumption questions solely in the perspective of LSAT author who presents the argument assuming that his/her argument is valid/airtight even though we can still see the reasoning flaw in it? That said, we normally only care about the validity, not the truth of the premise nor conclusion but do I not have to worry about the validity when it comes to the assumption questions? I'm confused about "what must be true in order for the CONCLUSION to be TRUE" in a sense that we simply take the presented premise and conclusion as true since even the argument consists of false premises could be valid.

Any help would be greatly appreciated. Thanks!

[Adam Tyson]

Thanks for the question, dlddls37! I see your confusion here, and I think I can help.

In an Assumption question, you are right that we need to put ourselves in the mind of the author. We do not have to accept that his argument is valid - it's almost certainly NOT a good argument, because something has been left out. However, we have to approach it with the idea that the AUTHOR thinks he is right, and that means there are certain things that he has to believe are true, even though he didn't say them. Those are the assumptions, and those are what we are looking for.

In other words, if the author is correct, then certain unstated claims must also be correct. If the conclusion is valid, then the assumption must be valid.

That is why the Assumption Negation Technique works so well - it is the contrapositive of that relationship between the conclusion and the assumption! If the conclusion is valid, the assumption must be valid, so if the assumption is false, then the conclusion is no longer valid. Look for the answer which, when negated, invalidates the conclusion of the argument.

The short version: for an assumption answer, we are not looking for something that must actually be true, and we do not have to accept that the argument is good. Instead, we are looking for something that the AUTHOR must believe to be true, because he thinks his argument is good.

[dlddls37]

Thanks! You are my Tylenol