Logical Reasoning Help: Necessary Assumption

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• 2 Likes

  Burden.of.Floof Core Member

  March 2021 1050 karma

  Those two definitions of a necessary assumption feel like they're in contradiction, and they would confuse me. If a necessary assumption isn't true, the conclusion cannot be true. But, a necessary assumption is rarely enough on its own to make the conclusion true. That can only happen if the necessary assumption is also a sufficient one, which does happen occasionally, but at the end of the day it still has to be a NA. I think Ellen Cassidy's definition and JY's can work in conjunction to give you a pretty comprehensive understanding of NA questions, those are the techniques I would go with. I wouldn't think of an NA as a premise that can potentially make the conclusion true. It's more like, an invisible consequence of validity. Something that must be true, something that is triggered by the validity of the argument, but we don't normally think about it unless we're asked about it specifically.

  When you do NA questions untimed are you having trouble? Or is it only under timed pressure?
• 2 Likes

  dawgslaw123 Alum Member

  March 2021 edited March 2021 138 karma

  Ok, if its a necessary assumption than it is NECCESSARY for the conclusion, not "potentially valid". Look for the AC that without it the argument wouldn't make sense.
• 3 Likes

  TheSwanQueen Member

  March 2021 88 karma

  What's helped me tackle the NA questions I've run into is to look for an AC that, if negated, would totally destroy the argument the stimulus is trying to make. (JY discusses this in the cc and his explanation is much better than mine--take a look if you haven't already)

  This simple litmus test of "If the statement in this AC were not true, would the argument still hold water" has been pretty effective for me.
• 1 Like

  Lets Get This Bread Core Member

  March 2021 63 karma

  @"Burden.of.Floof" For me, it's only under timed pressure. Like, I'll get the answer right but that's only if I work through it. Thank you so much for clarifying!
• 2 Likes

  Burden.of.Floof Core Member

  March 2021 1050 karma

  I am convinced more and more every day that this test is just one giant reading comprehension exam. (I'm not quite sure how to tie this in, but I needed to put that out into the world haha)
• teechj117 Alum Member

  March 2021 edited March 2021 296 karma

  Necessary assumptions always go without being stated. They are the obvious thing that the author assumes to be true. Imagine a golf player. All of their practice is sufficient to becoming a better player, but they can't be called a golf player unless they know how to swing a club. Swinging a club (to put the ball in the hole) is necessary to play the game. It's tricky, because we normally don't think about these things at all.

  The author is assuming everyone in the room understands the connection just because it's that obvious, but in order for the argument to be valid, you have to clarify that connection.

  @"Burden.of.Floof" You're right. It definitely challenges you to question what you read with a critical lens. It also calls to define what we take for granted

  "I wouldn't think of an NA as a premise that can potentially make the conclusion true. It's more like, an invisible consequence of validity"

  This twisted my head early in my prep. I used to associate NA with just that, but I think now, like you are saying, is a mistake that the test makers prey on.