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When would one negate the Sufficient side?

LeoFiro8LeoFiro8 Alum Member
edited November 2014 in General 244 karma
Me and a student were studying when we got a bit confused over when to negate the sufficient. Consider these two examples:
If you are a rabbit you are white.
R->W
No rabbit is white.
is it /R->W or R-> / W
I feel like the second one explains If you are a rabbit you are not white and the first one says no rabbit is white. Can somebody for the last time explain when the sufficient gets negated and when the necessary? something concrete to remember would be much appreciated, I know this might sounds basic but after awhile you just get confused...
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Comments

  • harrismeganharrismegan Member
    2074 karma
    If your statement is:

    If Rabbit --> White
    The contrapositive is /W ---> /R
    If you are not white, then you are not a Rabbit.

    If you're taking the negation...
    If Rabbit ---> White

    It would be:
    Some Rabbits are Not White.
  • LSATPWNAGELSATPWNAGE Alum Member
    edited November 2014 43 karma
    "No" is a negate necessary indicator, group 4. so, No rabbit is white = R-->/W or W-->/R
    "If" is a sufficient indicator group 1. So, if you are a rabbit then you are white= R-->W or /W-->/R.
  • _FIDELIO__FIDELIO_ Alum Member
    edited November 2014 98 karma
    No rabbit is white

    Group 4-Negate Necessary

    W---->/R
    R----->/W

    Now if you wanted this /R----->W

    you could say "You are either a rabbit OR white"

    which would be Group 3 Negate Sufficient.
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