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I have a question on negation. On prep test 58 section 1 question 25. the line Handmade foundations are never found on wigs that do not use human hair. Is diagrammed as HF------>HH. Shouldn't it be ~HF ------> HH. It is group 4. So you pick an idea ~HH, you negate it ~HH --->HH AND MAKe it necessary. The other idea is the sufficient. So how do we end up with HF INSTEAD OF -HF?
Shouldn't it be
~HF ---> HH?
https://classic.7sage.com/lsat_explanations/lsat-58-section-1-question-25/
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7 comments
The problem it seems is the first clause, and the placement of "never" is confusing you.
You cannot just simply negate the clause and keep it in the same place.
Consider this: "no cats are dogs"
You would diagram this as "if Cat, then not dog". That is, you keep the first subject and negate the second. It would be incorrect to say "if not cat then dog" which is what you are doing. This creates a situation in which everything and everyone is either a cat or a dog, rather than the initial meaning of you can't be both a cat and a dog.
Applying this back to the question:
"Handmade foundations are never used on wigs that do not use human hair"
If you used "no" instead of "never" it may become clearer to you.
No handmade foundations are used on wigs that do not use human hair.
So, keep the first subject and negate the second.
If handmade foundation, then not not human hair.
Of course, the double negative here isn't grammatically correct, and so they essentially cancel each other out. This leaves: if handmade foundation, then human hair.
@jmac286 As @coreyjanson479.janson35 said, trying to understand the sentence intuitively will help make better sense of its meaning. I picture in my head a row of wigs which I now know did not use human hair. What can be said of these wigs? Well according to the sentence you will not find a handmade foundation in them. I conclude: wigs with /HH --> find /HF.
@coreyjanson479
Handmade foundations are never used on wigs that do not use human hair"
ok, so not HF, then not HH or flipped as HH---->HF. The lesson/ method is of no help either because of my previous post, it would still give a wrong answer.
Your a/c looks like a reversal to me, so I need to understand why it would go that way, to me it looks like you are reversing the order they come in the sentence, which is why I am confused. That and the lesson suggest it should be something different.
Another way to read the first sentence:
If a handmade foundation is found, it is never on a wig that does not use human hair.
"Never...not" may be confusing you. So let me ask you this: what does it mean if I said "it's never not raining in South Florida"? You would quickly and intuitively understand that it is always raining in SoFla, and you wouldn't have to apply any conscious rules to understand it. Use the same approach on the "never...not" above and change never-not to always:
If a handmade foundation is found, it's always on a wig that uses human hair.
How come you changed the word ordering like that. And more importantly how did you know to do that? And even then, it is still inconsistent with the negatation lessons. http://classic.7sage.com/lesson/4-translation-groups-cheatsheet/
See #4.
"Handmade foundations are never used on wigs that do not use human hair"
So what do we know about wigs that do not use human hair? Is there anything that must be true about these wigs? In fact, there is: on these wigs it must be true that handmade foundations are never used. So, if a wig does not use human hair, then it does not have a handmade foundation.
/HH--->/HF
Or, it's contrapositive:
HF-->HH, which is what you have above.
Sometimes is easiest to try to look at these kinds of sentences intuitively rather than trying to apply rules. Twist the sentence around in your mind a little bit, and make sure that what you are diagramming accurately represents what is said.
/HF-->HH is something we do not know from a close read of the initial sentence.
IF a wig does not use human hair, THEN no handmade foundations will be found.
/HH --> /HF.