Necessary Assumptions

Comments

• nicole.hopkins Inactive Sage Inactive ⭐

  July 2015 7965 karma

  What phase are you at in your prep?
• 4 Likes

  gs556 Member Inactive Sage

  July 2015 568 karma

  Necessary assumptions are subtle but crucial.
  
  The number one way LSAT writers will try to trick you on these questions is by fooling you into picking a sufficient assumption.
  
  The best strategy is to negate the answer choices and see what happens to the argument. If the argument can survive, eliminate the answer choice, no matter how tempting it seems. The right answer choice will destroy the argument when negated.
  
  example:
  
  Donald Trump is very popular in red states. Therefore, he will be the republican presidential candidate for 2016.
  
  *NA question stem*
  
  A) Trump is in the lead in the polls
  Trump can capture a majority in a national election
  C) Trump is extremely popular with the base of republican voters
  D) Trump is a citizen of the United States
  
  A, B, and C are all great reasons why the argument might be sound, but D is the only necessary one. If Trump is not a U.S. Citizen, he is not eligible to be elected president and will not be nominated. The argument could still feasibly survive even if A, B or C were NOT true.
• 3 Likes

  nye8870 Alum ⭐

  July 2015 1749 karma

  E) This is gonna be HUGE !!
• 1 Like

  c.janson35 Free Trial Inactive Sage Inactive ⭐

  July 2015 2398 karma

  Yup, definitely use the negation method. It really helps you to see why something is "necessary."
  
  Also something to note: a necessary assumption doesn't have to strengthen an argument, so you may be having a tough time with these questions because you have the wrong mindset. In fact, there can be (and most often are) a bunch of necessary assumptions that must be true for an argument to have any chance at being valid.
  
  For example, in the question above it is absolutely necessary that D be true for the argument to hold; without it, there's no chance that Trump could be the candidate. But there are also a bunch more necessary assumptions that must be true for this argument! For example, before the nominee is selected, it must be true that Trump doesn't withdraw his candidacy, it must be true that Trump doesn't die in a freak toupee accident, and it must also be true that Trump is not abducted by aliens and deposited on another planet without any chance of returning. None of these would strengthen the support-conclusion relationship, but they are all necessary if the conclusion has any chance to be true. (And to prove it, try negating them to see!)
  
  Hope this helps!
• iustitia Member

  July 2015 30 karma

  Thanks guys!!!
  
  I am in the PTing stage!
  7Sage community, rocks!
• Pacifico Alum Inactive ⭐

  July 2015 8021 karma

  I think JY really does a great job with his bridging/blocking analysis and the more I keep those in mind and pair it with the negation test, the more successful I am during PTs. When I get away from those ideas I tend to wing it in an overconfident manner and pay dearly for it. Sure it's ultimately a crutch but chances are you'll likely need one or two and for my money this is a better one to have.
• 1 Like

  DumbHollywoodActor Alum Inactive ⭐

  July 2015 7468 karma

  How’s your negating ability? That has to be top notch. If not, I’d review that in the logic section. And I agree with @Pacifico. Keeping “blocking” and “bridging” in the back of my mind for NA really stops me from making a dumb mistake.
• ENTJ Alum Inactive ⭐

  August 2015 edited August 2015 3658 karma

  @gs556 That's a great example. I especially like your sucker choice in there. People would negate (B) and think...well you have to win the majority of votes in a national election. But not so! The stim talks about the republican primary and not the national election. And even in a national election, you can lose the popular vote and still win through the electoral college.