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General questions relating to the LSAT Logic Games.
  • Posts: 2
  • Joined: Jun 23, 2020

I was wondering how you would diagram a rule like:
If B does not occur, then H occurs or I occurs but not both.

I am getting stuck on how to diagram the "Or/ but not both." Would it be correct to say:
B :arrow: H + I
plus: B :arrow: H or I

I am missing inferences based off of the contrapositive and want to make sure I am diagramming this right!

Thanks in advance,
 Luke Haqq
PowerScore Staff
  • PowerScore Staff
  • Posts: 274
  • Joined: Apr 26, 2012
Hi Emily!

The second of your diagrams seems like the best way to represent the conditional reasoning. While it's not necessarily as great as having a specific strategy or precise way of dealing with "but not both" language, there are still things that you can do to flag the necessary material for yourself on the game.

Thus I'd add a parenthetical to the diagram so that "If B does not occur, then H occurs or I occurs but not both" would be diagrammed as:

B :arrow: H or I (but NOT BOTH)

Having "not both" in caps like that can help you keep an eye out to avoid such a possibility.

Another visually useful way of depicting this would be to have another rule taken in conjunction that has B on the left side of the arrow, and an H-I not-block on the right side. With those two rules, you'd know that B implies H or I, and you'd also know that B implies that you can't have an H-I block.

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