valid arguments

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• 1 Like

  dcdcdcdcdc Alum Member

  May 2016 382 karma

  You can print these two pages:
  
  1-3: https://7sage.com/lesson/valid-argument-forms-1-3-of-9/
  4-9: https://7sage.com/lesson/valid-argument-forms-4-9-of-9/
• 1 Like

  esteerose Alum Member

  May 2016 382 karma

  Thank you!! I forgot to star them.. Thanks for the help.
• quinnxzhang Member

  May 2016 edited May 2016 611 karma

  Argument form 6 is INVALID. If there are no turtles and if nothing is named after Italian artists, then both premises are true and the conclusion false.
  
  In order for number 6 to be valid, you would need an additional premise: there are some turtles. Maybe this is an innocuous assumption for LSAT purposes, but in the interest of correctness, I think 7sage should at least footnote this. I firmly believe that the logic taught in LSAT courses shouldn't directly contradict the classical logic textbooks informing the logic used on the actual exam.
• apublicdisplay Alum Member

  May 2016 696 karma

  Agreed with @quinnxzhang I've always learned that to take A –> B and A –> C and draw the conclusion B some C, you must assume that there is at least 1 member in A. However, I can't say entirely why the assumption of at least 1 is used for this example and not for other conditional statements.