gti24 wrote:Thanks for doing this! I had a few questions about LR that I still can't seem to figure out.
For necessary assumptions, what is your thought process when approaching these questions? Am I suppose to be looking for an answer that addresses the gap between the conclusion and the premises or just something that the conclusion can't be true without.
I'm looking for a flaw, not necessarily a gap. Gap is a way of describing a type of flaw. If there's a gap, I see it (usually) and if the flaw can be described in some other way, I see that (usually). The question I ask myself is:
1. What's the conclusion
2. What's the evidence
3. Why is this wrong? (Or: How could this be wrong?)
Note that sometimes, before step 3, you need to ask yourself "how could this be right?" or "what are they trying to say?" This is really another way of framing the identification of conclusion/reasoning. But I've noticed some students will say they've found the conclusion/reasoning, yet they don't know what the argument is trying to prove.
I'd like to talk a moment about this process of recognition of gaps. I wasn't born able to recognize a "gap" in an argument and name it a "gap". I learned. You should review NA assumption questions, and study the various forms the flaws take. After you get a solid grasp of 50+ questions with gaps, you should start to have an intuition for what a gap is and recognize it. (Note: I just made up the 50+ number. I have no idea what the actual number is)
Ways to accelerate this process are: talking about questions with a study partner, and repeating hard questions to develop mastery the second and third time through.
All that said, gaps are common. The conclusion will mention a term not in the evidence, and the assumption is that they're linked. E.g. "Good LSAT scores help students get into law school. This shows that schools value analytical reasoning." The assumption is: LSAT scores show analytical reasoning power.
gti24 wrote:When using the negation test, if one of the answers casts doubts on one of the premises, doesn't that invalidate the whole stimulus?
I don't think in these terms. In general, the LSAT does not "cast doubt on" or disprove premises. An answer choice might add context that shows a premise is not as strong as it seemed, but the premise will still be true.
With negations, you're looking for something which destroys the conclusion.
Protip: some negations are useless. You have to take the very slightest negation. For instance, negating "most" is worthless unless the conclusion was in terms of most. Negating most to not most means moving from 51% to 50%. Even in a parliamentary vote, this never has an effect on anything. Who cares if 51% of people vs. 50% of people like you? You wouldn't even notice the difference.
Likewise, negating many to not many is not significant. You have to take the low bound of many, and the high bound of not many. Maybe it's 20% to 19%. I never use actual numbers, just illustrating the magnitude of negation you're supposed to be using.
Whereas, negating some to none is significant. There is a big different between some and none. But it depends on context. For instance, all to not all can be significant, or it can not be. You wouldn't care if "not all" of the people you met liked you, because not all should be 99% when you're negating. But if we're talking about whether the safety of a nuclear power plant is guaranteed, then not always safe (99% safe) is suddenly significant.
I advise you to think in specifics. Suppose I say "all americans are nice". Here's how I want you to think about the negation: All Americans are nice except one guy in Arkansas named Bob. Literally everyone else is nice.
You could say "not all americans are nice" or "some americans are not nice". But the specific phrasing above captures the uselessness of this negation (in this context). You're trying to prove an idea wrong, in the slightest way possible.
The correct answers often have no wiggle room when negated. No matter how you do it, they wreck the argument.
gti24 wrote:What's the best way to approach logically complete questions?
Sufficient assumption questions? They've gotten more formulaic on recent tests, say 52+. Not every questions follows this form, but many do.
1. Identify the conclusion, e.g. A --> D
2. Split it apart: A _____________________ D (I am only underlining so that TLS will display the letters apart. Spaces don't work)
3. Fill in the evidence: A --> B --> C ______ D
4. What's left is the gap, and will be the right answer: C --> D (or ~D --> ~C)
Maybe 60% of SA questions follow this format, and once it clicks they're really, really, really easy.
gti24 wrote:When I'm reading a stimulus for an assumption family question (sufficient, necessary, strengthen, weaken), is there always going to be a faulty gap between the support and the conclusion?
No. As with NA questions, I don't think in these terms. I instead ask "how could this be wrong?". For strengthen/weaken questions, sometimes I spot no obvious error. The right answer will come a bit out of left field, but will strengthen/weaken the argument nonetheless.
For instance, consider this argument:
"Bob wants to buy a sandwich. He has his wallet, and he's going to the store with the intent to buy a sandwich. The store is open, and they sell sandwiches. Therefore, Bob will succeed in buying a sandwich."
This is already a pretty solid argument. Of course, the LSAT wouldn't give an argument this good, but I've seen some similar. Let's look at how we could strengthen, weaken it.
Strengthen: The store takes visa, and bob has a visa card with credit on it. Bob's wallet has enough cash to pay for a sandwich.
Weaken: Bob's wallet is empty. The store is in the middle of being robbed, and can't sell sandwiches. A fire has started in the back of the store, and it will be evacuated by the time bob gets there.
I certainly wouldn't prephrase any of those. But because I know the conclusion/reasoning, I'm prepared to say "ah yes, those strengthen/weaken" the argument.
What I'm saying is this: If I spot a "gap", then I will expect that is going to be the answer, and I'll form a prephrase. But there may be other flaws. And there may not be an obvious flaw. In all cases, I mostly focus on conclusion/reasoning.
Then I try to take a broad view of the situation. If possible, I'll put myself in Bob's shoes, and imagine what might prevent me from getting a sandwich.
Hope that makes sense. Figuring out flaws is a subtle art, and contrary to received opinion, it is very helpful to personalize a situation and apply real world reasoning (as long as you don't make up assumptions).
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