If Norton is scheduled for the fifth performance, which one of the following could be true?

Emil-Kunkin February 2, 2023

Hi, the only things that trigger the rule in question are the sufficient conditions, that being if L is 3 or if N is not five. We know nothing about the world if N is five, other than that L could be three.

Emil-Kunkin February 2, 2023

I think you're doing an illegal reversal.

Michael March 15, 2023

I have now asked 2 different barred attorneys that I know and they both agree that this is not the case. I know that is an argument from authority and all but this is not clicking with anyone I have asked so I am wondering how to keep from doing this on future similar questions.

The rule reads: "Lalitha performs third only if Norton performs fifth"

So L can only be 3rd if N is 5th. L3 is dependent on N5 being true. Since N5 is true then L3, being dependent on that, is also true.

What you are saying is that the rule is: L3 -> N5
but the rule reads: N5 -> L3

This would be a question that would get thrown out due to 90% of people missing it if I had to guess. Again just asking how I can keep from making this mistake in the future as myself or anyone I ask cannot seem to logic it out lol

Emil-Kunkin March 17, 2023

Hi, I think the issue is in assuming L can only be third if N is 5. Only if introduces a necessary condition, so the rule is indeed N5 -> L3.

I think you had a good grasp of this in your reasoning. L3 does indeed depend on N5 being true. Here, N5 May or may not be true, so we don't know anything about L3.

Looking forward I would try to turn sufficient and necessary statements into something a bit more common sense. My two favorite ways to approach this would be as follows.

You can be president only if you are over 35.
(If potus -> old)

You can be in Chicago only if in Illinois.
(If C then I)

In both of these cases, being over 35 and being in IL do not guarantee anything.