PT 26 Sec 2 Q16 Forum

[LateNight]

How do you interpret this?!!

Every B which is also L is either A or C. Last year all B's that were C's were also A's. Therefore, every B which was also L was a A.

my answer: Because if all B's that were also C's were also A's, then all B's which also L's have to be A's since they can't be C's because then they would be both.

But does either or imply, one but not BOTH. In formal logic or generally means could be in either categories or both, I would take the either to mean "not both..."

Is that right?

[zworykin]

"Either" does NOT imply "not both." It's either or both; the only eliminated possibility is 'neither.' Don't look for implications that aren't necessarily there. If it's "either but not both" then the question will say so explicitly.

[LateNight]

Really?

So you are either black or white.

Then you can be both?

[kk19131]

26????

What year is that from?

[WestOfTheRest]

Just diagram it.

B=L --> B=A or B=C
B=C --> A
B=L --> A

[zworykin]

Really?

So you are either black or white.

Then you can be both?

No. Bad example. The question doesn't say that, and wouldn't say that. It might say that you are either broke or unemployed, or that you are either a vegetarian or a Democrat, or that you are either Italian or a dentist.

Throw away outside ideas of how things work. This is the LSAT. The rules aren't necessarily the same. If it doesn't say "not both," then both is still an option. If both is not an option, the question will say so explicitly.