Is that a valid argument form?

Comments

• 1 Like

  If Glory then Guts Member

  July 2022 175 karma

  I mean it depends on the content, but that form certainly could be a valid argument.

  Consider the claim, "The painting is completely red and completely green". If that claim is true, then you've got a logical contradiction. So to conclude that the claim must be false would be valid inference.
• 2 Likes

  AlexLSAT. Alum Member

  July 2022 802 karma

  This AC is saying that the stimulus says that the necessary condition is not true, so the sufficient condition can not also be true... which would in practice look something like:

  A > B
  /B

  ---

  /A

  This is a simple contrapositive and indeed a valid argument form.
• If Glory then Guts Member

  July 2022 edited July 2022 175 karma

  @AlexgLSAT said:
  This AC is saying that the stimulus says that the necessary condition is not true, so the sufficient condition can not also be true... which would in practice look something like:

  A > B
  /B

  ---

  /A

  This is a simple contrapositive and indeed a valid argument form.

  I'd argue it's slightly different to the standard contrapositive. I'd map it like this:
  A ---> /A

  ---

  /A

  Would you agree?
• AlexLSAT. Alum Member

  July 2022 802 karma

  @"If Glory then Guts" said:

  @AlexgLSAT said:
  This AC is saying that the stimulus says that the necessary condition is not true, so the sufficient condition can not also be true... which would in practice look something like:

  A > B
  /B

  ---

  /A

  This is a simple contrapositive and indeed a valid argument form.

  I'd argue it's slightly different to the standard contrapositive. I'd map it like this:
  A ---> /A

  ---

  /A

  Would you agree?

  Claim that has consequences: A > B
  Consequences proven false: /B
  Found claim to then be false > /A
  Conclusion: /B > /A

  This is not as simple as just negating A, because the AC states that claim (sufficient) > consequences (necessary). I think this is still just the standard contrapositive. Claim is made with attached consequences. Consequences are then negated, then it concludes that the claim can not be true.

  Hope this makes sense!
• If Glory then Guts Member

  July 2022 175 karma

  @AlexgLSAT said:

  Claim that has consequences: A > B
  Consequences proven false: /B
  Found claim to then be false > /A
  Conclusion: /B > /A

  This is not as simple as just negating A, because the AC states that claim (sufficient) > consequences (necessary). I think this is still just the standard contrapositive. Claim is made with attached consequences. Consequences are then negated, then it concludes that the claim can not be true.

  Hope this makes sense!

  Hmm interesting, I can see how you can use that mapping and that it may be more pertinent in regards to an actual lsat question. Perhaps this is a bit futile without an actual stimulus. But taking lawgirl's comment in isolation, I'm inclined to interpret it as: The truth of A has consequences that are not true. Where A is just any claim, conditional or otherwise. I think a good example is my one from above, but I could also imagine something similar in Peter Unger's "I do not exist" claim. Whereby if the claim is true, it can not actually be made (thus having consequences that are false). Interesting point anyway and I reckon we'd both arrive at the same answer in a test though--- but happy to discuss further if you want to.