Meaning of "either or" page 180

    • May 22, 2016 at 12:50 pm #1891

      If she owns, she also owns either Q or R. (pg 180)

      Does either change or restrict the meaning of “or” here?

      The solution shows S -> Q or R; Q and R -> S

      Usually, S could cause Q, R, or Q&R. Does “either Q or E” restrict this to S causes Q or R but not Q&R?

      If the latter, wouldn’t the contra positive be QR OR Q & R -> S ?

      Basically, I’m wondering if either or on the LSAT basically means but not both


    • May 22, 2016 at 12:51 pm #1892

      Replace cause with trigger. Posting from phone as I go so it’s a bit hard to edit posts. Apologies!


    • May 23, 2016 at 7:58 am #1895
      LSAT Dan

      I don’t think that the appearance o the word “either” changes the general rule – if you’re not specifically told “but not both,” then “or” is inclusive. For instance, “To be accepted to college, one must have either a high school diploma or a G.E.D. Certificate” would not be logically incorrct and would not imply exclusivity. I haven’t checked, but with one exception, I strongly doubt there are any situations where it’s supposed to be the exclusive “or” and they don’t say “but not both.”

      The exception would be situations where the inclusive ‘or’ would be impossible. For instance, in a 1-to-1 sequencing game where it says something like, “X is in position 3 or position 5.”

      When I say “but not both,” I mean to include any such similar limiting language.

    • May 23, 2016 at 10:05 am #1898
      Mike Kim

      Dan is right — the either doesn’t make the “or” exclusive and if they want the either/or to be exclusive they will say so (or it will, as Dan stated, be a situation that naturally limits the options).



    • May 23, 2016 at 12:32 pm #1901

      Ok – understood.  I appreciate it.  I sort of meant to delete this, as I got to a page a bit later in the Trainer on that sort of explicitly stated what you have.

      I think the reason it sort of confused me is that it was the only “either or” in the drill, if I recall correctly, so it kind of stood out.

You must be logged in to reply to this topic.