Negation Q about SA

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• 2 Likes

  Logician Alum Member Sage ⭐

  January 2021 edited January 2021 2464 karma

  Hey there, to answer your question- no you cannot. The reason the negation test works with necessary assumptions is because the correct answer is just that- it’s necessary for the argument and therefore must be true. So when you deny it, the argument no longer works.

  Sufficient conditions on the other hand are not necessary for the argument (they need not be true) they’re simply sufficient for reaching the conclusion. So if you were to negate an SA answer choice it would not destroy the argument, therefore the negation test would not be applicable.

  Hope this helps!
• 1 Like

  masi Alum Member

  January 2021 170 karma

  @EbethStudent16

  I will put it this way.

  You want to write the LSAT. The cost is $US200.

  Therefore, I can write the test.

  The sufficient assumption would be anything above 200 dollars.

  Say you negated this such that (you do not have $US500). Will this mean you don't have enough money to writ the test.

  Clearly not. You could have 499 or 380 or 280 and so on. This is why negating sufficient will not work.

  Now for the necessary.

  Say you negate that you don't have at least 200. This will destroy the argument.

  So one answer choice that the LSAT writers will put is this. "You have at least $US200". If you negate this ( I don't have 200) this will mean you cannot write the test.

  This would destroy the above argument.

  The rare case:

  It is both sufficient and necessary to have 200 dollars to write the test.

  But don't worry about this. You will hardly come up on a question that would test for both necessary and sufficient assumptions.

  Hope this helps.

  Good luck
• EbethStudent16 Alum Member

  January 2021 82 karma

  Thank you so so so much for taking the time to write these. This absolutely helped so much! @masi @Logician