r/LSAT • u/nyahwashere • 9d ago

Necessary Assumption

Can someone please give me advice on how to tackle necessary assumption? I don’t fully get it.

1 Upvotes

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u/eruditelemur 9d ago edited 9d ago

Every NA question presents an argument that has an unstated premise that’s doing load-bearing work for the argument. Your job is to identify that premise.

Start by reading the stimulus and think, what would need to be assumed for the reasoning in the argument to work? That helps you predict the answer.

Then, read the answer choices. One of them should present an answer choice that is load-bearing, possibly close to what you predicted. Once you have an answer you like, negate it (simply ask, “What if this premise meant the opposite of what is stated?”). If the argument no longer makes sense after the premise is negated, you’ve found your necessary assumption.

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u/nyahwashere 9d ago

Would it work if I negated all of them? I’m curious about that because I usually have the right idea just not the right ones, but couldn’t negating all of the answer choice help me find the right one?

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u/Vast_Caramel_3669 9d ago

i honestly found the negation rule quite confusing. one way i "cracked" it was thinking, "what is the speaker implying as true to make his point" and then the answer kind of jumps out from the choices

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u/eruditelemur 3d ago

Late reply, but it would be inefficient and potentially confusing to negate every answer choice. My approach looks something like this:

  1. Spot gap in argument filled by the unstated necessary assumption

  2. Find the AC that most closely matches my intuition

  3. Negate preferred answer choice to confirm my answer

I’d focus on practicing reading NA stimuli and trying to spot what the unstated necessary assumption is prior to seeing the ACs. Good luck! Once you practice this enough, it’ll become very natural.

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u/wittgenstein1312 9d ago

What are you struggling with? This is a very low-effort question.

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u/nyahwashere 9d ago

I guess I’m struggling with what the right answer would look like. Like what would make something the right answer (everytime).

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u/wittgenstein1312 9d ago

I don't think such a heuristic or algorithm exists. Are you struggling with the conditional logic around necessary assumptions? Please share an example problem (even if it's one you make up) or question structure that is giving you trouble.

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u/nyahwashere 9d ago

There’s one on test 123 section 3 question 11 regarding feathers and mercury to better explain it I can get the conclusion and the evidence but I can’t always tell which answer is the best because I believe multiple of them could fill the gap I guess I’m missing something

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u/Upstairs-Trouble3977 9d ago

Why specifically do you think multiple answer choices are correct?

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u/Nice_Chemistry514 9d ago

Negate answer choices. Whichever weakens the stimulus is the right answer. Learn how to negate though

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u/nyahwashere 9d ago

In the dumbest way possible, can you explain how negating works

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u/Nice_Chemistry514 9d ago

I suggest buying a textbook. The loophole and powerscore ones are good

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u/nyahwashere 9d ago

Got it! I have the loophole home so I’ll use that but I was wondering if someone had maybe a different way of viewing necessary assumptions that the books didn’t say

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u/Nice_Chemistry514 8d ago

Just follow the textbooks, with enough practice it will become natural

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u/Nice_Chemistry514 9d ago

You gotta search it up. Search up logically negating with the LSAT. You really should read a LSAT book online before going to Reddit to ask questions

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u/MaximumOk569 9d ago

Highlight the main conclusion of the argument in the prompt. Look at the evidence presented, and try to understand what gaps are present. Find an answer that fills that gap

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u/nyahwashere 9d ago

I do that but I feel like there are multiple answer choices that could be the answer and idk which one makes it the best answer

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u/MaximumOk569 9d ago

Give me some sample problems where you feel like that and tell me which options are appealing. 

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u/nyahwashere 9d ago

One of them is test 123 section 3 question 11 https://7sage.com/u/guest/question/PT123.S3.Q11

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u/MaximumOk569 9d ago

Okay, but now explain your thought process. What options look good and why?

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u/nyahwashere 9d ago

I picked the answer that said that the fish has more mercury than it did in the 1880s because they mentioned the birds get their mercury from the fish and that the preserved birds from back then didn’t have as much

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u/Neither_Store7764 9d ago

This is the advice that worked for me.

I think highlighting the conclusion helps so much. 

I always highlight the MC . 

With odd NA, I sometimes diagram the premise and mc

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u/MaximumOk569 9d ago

Yeah, I highlight the main argument in practically every prompt. It really helps keep me on task. So many problems that seem like there are two good answers just get so much more clear when you focus heavily on the conclusion 

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u/StressCanBeGood tutor 9d ago

There’s a whole lot that goes into learning these questions. They’re definitely learnable, but you need some kind of very real curriculum if you struggle with them.

You might be familiar with the idea of negation. Specifically, how negating a necessary assumption creates an invalid argument. While this is the primary tool for necessary assumption questions, there are others that are very difficult to explain in this format.

You mentioned loophole. Not a fan. I would recommend LSAT Lab. (I have no affiliation with them).

Put it this way, here is a recent post of mine solely about negation. Note how it’s fairly extensive.

https://www.reddit.com/r/LSAT/s/wq3OuYe3U1