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"Or" inclusive or exclusive?
Posted: Tue Aug 03, 2010 10:34 am
by Precessional
I was ponderin' this during my last LR session:
When "or" shows up in logical reasoning answer option, is it understood to be an inclusive or or as an exclusive or?
Consider the illustrative example:
Tom or Jerry is addicted to crack cocaine.
Two of the possiblites are obvious:
(i) Tom is addicted. Jerry is not.
(ii) Jerry is addicted. Tom is not.
If the "or" is an inclusive or, then we have a third possiblity:
(iii) Both Tom and Jerry are addcited to crack cocaine.
An exclusive or would exclude possiblity (iii)
So yeah. It could be that the differentiation is so esoteric that it'd almost never be a controlling factor in getting a LR question right or wrong. Even then, it'd be nice to get an answer (if there is one).
Re: "Or" inclusive or exclusive?
Posted: Tue Aug 03, 2010 10:36 am
by d34d9823
I read it as exclusive. I did well on the LSAT. There is not necessarily a correlation between these two statements.
Re: "Or" inclusive or exclusive?
Posted: Tue Aug 03, 2010 10:37 am
by 3|ink
"Or" simply means that one condition has to be. It does not necessarily mean that both cannot be unless it is proceeded by "but not both."
To answer your question, "or" by itself is inclusive because it allows for the possibility of both.
Re: "Or" inclusive or exclusive?
Posted: Tue Aug 03, 2010 10:39 am
by blurbz
3|ink wrote:"Or" simply means that one condition has to be. It does not necessarily mean that both cannot be unless it is proceeded by "but not both."
To answer your question, "or" by itself is inclusive because it allows for the possibility of both.
Re: "Or" inclusive or exclusive?
Posted: Tue Aug 03, 2010 10:40 am
by d34d9823
3|ink wrote:"Or" simply means that one condition has to be. It does not necessarily mean that both cannot be unless it is proceeded by "but not both."
To answer your question, "or" by itself is inclusive because it allows for the possibility of both.
If you read "or" as inclusive, what is the purpose of "and/or"?
Re: "Or" inclusive or exclusive?
Posted: Tue Aug 03, 2010 10:42 am
by 3|ink
d34dluk3 wrote:3|ink wrote:"Or" simply means that one condition has to be. It does not necessarily mean that both cannot be unless it is proceeded by "but not both."
To answer your question, "or" by itself is inclusive because it allows for the possibility of both.
If you read "or" as inclusive, what is the purpose of "and/or"?
1) Clarification
and/or 2) the difference between common English usage and logic.
PS: I don't think you'll find and/or in the dictionary.
PSS: D34dluk3's LSAT > Mine. However, I'm very familiar with "Or" and know that it's purpose for logic is to indicate that at least one of the listed conditions must be present, not that only one of the listed conditions can be present. I actually debated the use of "Or" in college (English major).
Re: "Or" inclusive or exclusive?
Posted: Tue Aug 03, 2010 11:14 am
by d34d9823
3|ink wrote:d34dluk3 wrote:3|ink wrote:"Or" simply means that one condition has to be. It does not necessarily mean that both cannot be unless it is proceeded by "but not both."
To answer your question, "or" by itself is inclusive because it allows for the possibility of both.
If you read "or" as inclusive, what is the purpose of "and/or"?
1) Clarification
and/or 2) the difference between common English usage and logic.
PS: I don't think you'll find and/or in the dictionary.
PSS: D34dluk3's LSAT > Mine. However, I'm very familiar with "Or" and know that it's purpose for logic is to indicate that at least one of the listed conditions must be present, not that only one of the listed conditions can be present. I actually debated the use of "Or" in college (English major).
For what it's worth, I wasn't trying to imply that my LSAT makes my opinion better, just that I at least have some experience with this.
I'm very intuitive with my approach to language and I can't hang with the grammar types as far as split predicates and infinitive nominatives. I'm relying on how I understand it as spoken; spoken "or" is always exclusive in my mind. Of course, this could vary based on where you grew up, etc.
I agree with 3|ink as far as logical "or", but in a textual question, I'm more inclined to read it as spoken "or".
Re: "Or" inclusive or exclusive?
Posted: Tue Aug 03, 2010 11:28 am
by 3|ink
d34dluk3 wrote:
For what it's worth, I wasn't trying to imply that my LSAT makes my opinion better, just that I at least have some experience with this.
I think that intention was quite clear. I didn't take it any other way than what you say above. I was simply conceednig that point so I could bring up the fact that I debated the subject of "or" in college without sounding like a douche.
d34dluk3 wrote:
I'm very intuitive with my approach to language and I can't hang with the grammar types as far as split predicates and infinitive nominatives. I'm relying on how I understand it as spoken; spoken "or" is always exclusive in my mind. Of course, this could vary based on where you grew up, etc.
Quite true. When most people say "or", they are probably referring to two exclusive conditions. However:
Merriam Webster wrote:4 —used in logic as a sentential connective that forms a complex sentence which is true when at least one of its constituent sentences is true
http://www.merriam-webster.com/dictionary/or
This means that the sentence, or for our purposes, "statement" is true when
at least one of the conditions is true.
d34dluk3 wrote:
I agree with 3|ink as far as logical "or", but in a textual question, I'm more inclined to read it as spoken "or".
As would I.
Re: "Or" inclusive or exclusive?
Posted: Tue Aug 03, 2010 11:41 am
by Whitestone
If the LSAT wants to make an xor statement, they will go with 'either ... or ...'
Re: "Or" inclusive or exclusive?
Posted: Tue Aug 03, 2010 4:57 pm
by NYCLSATTutor
Logically it is inclusive. Or means at least one of the two conditions must be true. And means both conditions must be true. This is true for the entire LSAT.
It is true that oftentimes or in normal language is exclusive. However there are a whole bunch of assumptions that go along with speaking non-logically and part of the purpose of the LSAT is to see how good you are at shedding these assumptions.
You should ALWAYS treat or on the LSAT to mean "at least one is true, but it could be both" (unless it says "either...or").
Re: "Or" inclusive or exclusive?
Posted: Wed Aug 04, 2010 11:00 am
by Audio Technica Guy
It is inclusive unless the setup of the game necessarily makes it exclusive. Sometimes they clarify with "and/or" but sometimes they don't.
If it doesn't specify exclusive and it isn't a logical necessity that it be exclusive, you must understand it as inclusive.
Re: "Or" inclusive or exclusive?
Posted: Wed Aug 04, 2010 11:01 am
by Audio Technica Guy
d34dluk3 wrote:I read it as exclusive. I did well on the LSAT. There is not necessarily a correlation between these two statements.
It is absolutely 100% incorrect that it is exclusive.
Re: "Or" inclusive or exclusive?
Posted: Wed Aug 04, 2010 11:02 am
by Audio Technica Guy
Whitestone wrote:If the LSAT wants to make an xor statement, they will go with 'either ... or ...'
Or more commonly, they set things up so that it can't be inclusive in the first place.
Re: "Or" inclusive or exclusive?
Posted: Wed Aug 04, 2010 11:03 am
by 3|ink
Audio Technica Guy wrote:d34dluk3 wrote:I read it as exclusive. I did well on the LSAT. There is not necessarily a correlation between these two statements.
It is absolutely 100% incorrect that it is exclusive.
Definitely true for the LSAT. However, to D3adluk3's credit, I think that people often use it to refer to two conditions that are exclusive.
Re: "Or" inclusive or exclusive?
Posted: Wed Aug 04, 2010 11:18 am
by Audio Technica Guy
3|ink wrote:Audio Technica Guy wrote:d34dluk3 wrote:I read it as exclusive. I did well on the LSAT. There is not necessarily a correlation between these two statements.
It is absolutely 100% incorrect that it is exclusive.
Definitely true for the LSAT. However, to D3adluk3's credit, I think that people often use it to refer to two conditions that are exclusive.
yeah, in everyday language that is the case, but not logic (isn't so much an LSAT thing as it is a logic thing).
Same goes with unless. In everyday language we use it to mean both ways most of the time, where on the LSAT it means one ways.
Think of "I'm going to class unless it rains."
On the LSAT that just means that if it doesn't rain, I'm guaranteeing that I will go to class. In real life we usually mean that if it doesn't rain I will go to class
and if it does rain I won't go to class.
Re: "Or" inclusive or exclusive?
Posted: Wed Aug 04, 2010 11:32 am
by Kobe_Teeth
I think if you elaborate on the example used its pretty clear that "or" is inclusive. Consider the following:
If Tom or Jerry has crack cocaine then let's get some hookers tonight.
In this statement, if Tom AND Jerry both show up with crack cocaine then we can still get hookers! WIN!!
However, the way it was worded in the OP my original glance did not put it in that context since I am not in LSAT mode and I'd be willing to bet that's what happened with lion-avatar-person as well.
Re: "Or" inclusive or exclusive?
Posted: Wed Aug 04, 2010 3:39 pm
by KevinP
"Or" on the LSAT is inclusive unless stated otherwise. If it is exclusive they will usually denote that via "either... or... but not both".
Re: "Or" inclusive or exclusive?
Posted: Wed Aug 04, 2010 3:45 pm
by d34d9823
Kobe_Teeth wrote:I think if you elaborate on the example used its pretty clear that "or" is inclusive. Consider the following:
If Tom or Jerry has crack cocaine then let's get some hookers tonight.
In this statement, if Tom AND Jerry both show up with crack cocaine then we can still get hookers! WIN!!
However, the way it was worded in the OP my original glance did not put it in that context since I am not in LSAT mode and I'd be willing to bet that's what happened with lion-avatar-person as well.
Oddly enough, I read the first as exclusive and the second as inclusive. I don't know if it has to do with transitive vs. permanent properties or what.
Re: "Or" inclusive or exclusive?
Posted: Wed Aug 04, 2010 5:03 pm
by suspicious android
d34dluk3 wrote:Oddly enough, I read the first as exclusive and the second as inclusive. I don't know if it has to do with transitive vs. permanent properties or what.
It's just context clues that are telling you what the difference is. There's no special grammar structure going on. In colloquial English we use "or" exclusively, so we assume it means that unless there is a reason to do otherwise. There's a clear context clue in the second, so it's obviously inclusive. But the formal, precise definition of "or" allows it to be used inclusively, so you have to allow for that interpretation on the LSAT.
Re: "Or" inclusive or exclusive?
Posted: Wed Aug 04, 2010 5:07 pm
by dakatz
"Or" on the LSAT is NOT exclusive unless something is specifically stated to the contrary.
For example:
People who go to the ballpark eat hot dogs or peanuts
On the LSAT, you would take this to mean that, if someone goes to the ballpark, he eats a hot dog, peanuts, OR BOTH.