Which one of the following could be a complete and accurate list of the friends who appear together in a photograph?

Danielle on October 10, 2017

Question

How are R and Y in the same photo if R=> not Y?

3 Replies

Mehran on October 10, 2017

Hi @dtorres! You've mis-diagrammed the third indented rule.

"Raimundo appears in every photograph that Yakiro does NOT appear in."

This means that Yakiro's ABSENCE is SUFFICIENT to ensure that Raimundo is in the photo.

The positive is diagrammed as not Y ==> R
The contrapositive is diagrammed as not R ==> Y

This means you can't have a photograph from which BOTH R and Y are MISSING, but you could have a photograph in which both R and Y are present!

Hope this helps! This is a very important LSAT concept, so please let us know if you have any additional questions on this point!

Amanda on November 11, 2017

Thank you- so helpful

on October 6, 2018

I know this is the "not both" and "either/or" concept but im confused because the rule didn't state any of those key words. Should I take that to mean that if one has to be in, both CAN be in. But (in a different game for example) if one has to be out then both CAN be out? Because it's clear one of them HAS to be in. Sorry, is this making sense? Pls help.