Negating Assumptions on the LSAT
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Learning to negate answer choices on the LSAT is a key skill if you are really looking to push up your score, for lots of reasons. I tend to think there are two especially important ones. First, assumption questions (and one of the most-related question type, flaw questions) are quite common, and many students find it’s difficult to get all of the most challenging assumption questions correct without using the negation test. Second, negation can be useful for thinking out counterfactuals on inference and strengthen/weaken questions – more on this another time. Today, I’ll be writing about how to negate in general terms. In another blog post, I’ll get into specifics.
An important thing to keep in mind before jumping into this is that negation is not something you should plan to use all the time, even on assumption questions. Use negation to choose between two answer choices if they both seem like close contenders. Your first line of offense for assumption questions should continue to be based on issues of scope and spotting the logical gaps in an argument.
The Basics
You might be wondering what is so difficult about negation, and if you are, I would guess you have not gotten too far into your preparation yet. Often, working with students one-on-one or in a classroom I notice numerous mistakes when students try to negate, and often they don’t even realize they’ve made huge logical changes to the answer choice in the process of negating it. For this reason, I think it’s appropriate to start with a general example that shows in broad, simple terms the mistakes we sometimes make when we negate. Consider,
(1) The cat jumped over the mat.
That would probably be straightforward to negate, right? We could just negate the verb:
The cat did not jump over the mat.
That’s all well and good, but what about this sentence?
(2) A cat jumped over the mat.
Does that get negated the same way? Of course it doesn’t. I’ll talk about why in a second, but more interestingly, I wanted to point out that there are two ways to negate statement (2).
A cat did not jump over the mat
or
No cat jumped over the mat.
Though these two are phrased differently, they actually mean the same thing. Effectively both say that the mat has never seen a cat jumping over it (or should I say that the mat has never been jumped by a cat 🙂 ?)
Let’s consider one of these negations:
No cat jumped over the mat
Why can’t I use it to negate statement (1)?
Changing “the” to “no” misreads the meaning of the original in a way that does not simply negate the sentence. Since I used “the” in the original case (1), I was really only writing about a specific cat. I should have only cared about whether that cat had jumped over the mat. If all I wanted to say was that the specific cat did not jump over the mat, I did not need to prove the broad statement above, that no cat, ever, has jumped over that mat. Essentially, trying to negate in the second version I over-negated, a potentially fatal mistake in LSAT practice and law alike. I never want to do more heavy lifting (read negating) than I absolutely must.
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Philosophy
The most important question you should ask yourself when confused about how to negate a particular answer choice is, “What is the minimum I would need to show that disprove the statement above?” This minimum part is very important because often, in difficult cases, students over-negate because they are not paring down to the very minimum.
To see an example of these, consider the following. Imagine your classmate says to you, “I don’t have any friends in this class.” You’d probably respond to this by saying “That’s not true – everyone (or almost everyone here) is your friend.” But that’s a lot more than you’d have to say, and maybe a lot more than you’d want to say, if this classmate was going to ask you to prove your statement. A better idea would be to say more simply, “That’s not true – I’m your friend.” This might sound less promising, but it’s easier to prove, and, importantly, it’s enough to disprove your friend’s statement.
Let’s formalize this a little bit.
(3) No one in this class is my friend.
What do we need to negate here? Well, if we go back to our anecdotal version above, we see that all we need to show to disprove this (and consequently the negation of case (3)) is that
At least one person in this class is my friend.
That is the negation because it would make statement (3) untrue, though it might not comfort the speaker much to have one friend rather than none, but we are concerned with the logical statements above. Now, to give a few versions I might have anticipated a student giving mistakenly, consider each of these:
Everyone in this class is my friend.
No one in this class is not my friend.
I have a lot of friends.
Everyone is my friend.
All of these “overshoot.” Overshooting is bad. Bad on the LSAT because it shows an inability to determine the precise logical negation of a statement, and bad as a lawyer because you make your case more difficult for yourself than you really have to. From here onwards, make parsimony a central feature of your negation process. Also,make sure you can articulate how each one overshoots before you continue reading.
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Complicated Sentences with Multiple Things you Kind of Want to Negate
Now let’s consider the real thing. Consider this answer choice from an assumption question.
(4) Most people who suffer from ordinary mountain sickness recover without any special treatment.
The tricky part about negating this answer choice is that there are many parts of the sentence we could negate. To make it more obvious, I’ve broken it down by idea:
Most people who | suffer from ordinary mountain sickness | recover |without any special treatment.
Let’s break this down by negating each of these in turn and thinking about whether it produces the minimum that, if true, would disprove the original statement (4).
First, let’s negate the first chunk of the sentence, “Most people who.” This is a claim that at least 50% of a group of people do a specific thing. To negate this part, I’d say “less than half of those people”, or “not most.” This sounds a bit awkward, but it conveys the meaning:
#1 Less than half the people who suffer from ordinary mountain sickness recover without any special treatment.
Would this disprove statement (4) if true? It seems it would because it would show that not more than 50% of the group actually gets better without special treatment. This also seems pretty minimal. For example, so long as I could show that fewer than 49% of people got better this way, I would be set.
Let’s look at negating the second part.
#2 Most people who do not suffer from ordinary mountain sickness recover without any special treatment.
If true, would this disprove the original statement (4)? No, absolutely not. If you’ve been studying for the LSAT for some time, you’ll certainly recognize that this has a scope problem. We don’t actually care about people who don’t have ordinary mountain sickness – we care about people who do have the illness. This is definitely not the proper way to negate the statement.
If we negate the third part of the sentence, we have
#3 Most people who suffer from ordinary mountain sickness do not recover without any special treatment.
Like the first version of a negation, this seems as though it would disprove the statement. Here it would do so by talking about the same group of people (most of those who get this illness), but saying that they do not do what the speaker claims they do. Is this minimal? It seems like it, but let’s push on.
Negating the fourth portion of the sentence yields,
#4 Most people who suffer from ordinary mountain sickness recover with special treatment
This one sounds kind of funny, doesn’t it? We know what it means though, so maybe we can rephrase it a bit better as
Most people who suffer from ordinary mountain sickness recover after receiving special treatment
Oh! Now this actually looks a lot like # 3, which in turn looks a lot like #1. Indeed, if we really think about what they mean, they all mean the same thing, which is saying that more than half of people received some kind of special treatment before they get better, which is the opposite of what the answer choice says.
Moreover, it answers our requirement of parsimony too. We don’t need to show that no one can get better without special treatment – all we need to show is that such is not the case.
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Non Exhausted List of Terms and Their Negations
Now that we’ve talked about how to negate an answer choice, it’s also worth thinking about some standard negations that are likely to surface many times on your LSAT. Try to complete as many of these as possible. Feel free to answer in a comment. Answers will be posted in a week or so.
If you see… Negate with…I
All
Some
Most
Not all
None
Probably
Unlikely
Never
Always
Sometimes
Without
With
To be continued…