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 ashpine17
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#99491
why is it ok to diagram honest people and honest farmer the same way?
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 Jeff Wren
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#99908
Hi ashpine,

The short answer is that it works in this question because the term "farmer" appears in both the correct answer choice and in the conclusion and sort of drops out of the diagram.

If you look at the very first post on this question above, this is discussed in more detail.

Basically, Answer A "Every honest farmer is poor" could be diagrammed:

H + F -> P (if you're honest and you are a farmer, then you are poor.)

The contrapositive would be

not P -> not H or not F (if you're not poor, then you are not honest or you are not a farmer.)

This contrapositive would allow us to draw the conclusion that all rich farmers are dishonest, which would be diagrammed

not P and F -> not H (with rich being equivalent to not poor and dishonest being equivalent to not honest). Since rich farmers are farmers, the other option (of not being a farmer) is ruled out here.

This is a bit tricky, so the other explanations just left the farmer term out of the diagram for simplicity and clarity.
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 wisnain
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#106143
Hello,

I have a quick question about the 'either A or B' logic that's been bugging me lately.

1. From what I understand, unlike how we interpret it in everyday situations, the LSAT seems to approach 'either A or B' as ‘if not A, then B’, ‘if not B, then A’, and ‘POTENTIALLY BOTH (unless explicitly stated otherwise, such as ‘not both’). How should I go about diagramming this stimulus when there isn’t any additional clarification provided?

2. Also, why doesn’t ‘either A or B’ simply translate to ‘If A, then not B’, and ‘If B, then not A’, similar to how we interpret it in everyday life? Could you help me understand why the inclusion of ‘not’ at the sufficient part is necessary?

Thank you.
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 Chandler H
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#106148
wisnain wrote: Thu Apr 25, 2024 2:37 am Hello,

I have a quick question about the 'either A or B' logic that's been bugging me lately.

1. From what I understand, unlike how we interpret it in everyday situations, the LSAT seems to approach 'either A or B' as ‘if not A, then B’, ‘if not B, then A’, and ‘POTENTIALLY BOTH (unless explicitly stated otherwise, such as ‘not both’). How should I go about diagramming this stimulus when there isn’t any additional clarification provided?

2. Also, why doesn’t ‘either A or B’ simply translate to ‘If A, then not B’, and ‘If B, then not A’, similar to how we interpret it in everyday life? Could you help me understand why the inclusion of ‘not’ at the sufficient part is necessary?

Thank you.
Hi wisnain,

To answer your first question, diagramming this specific stimulus requires some contextual common sense. It's true that some situations can be described as "either A, or B, or both." However, in this context, we are talking about opposites: rich/poor, honest/dishonest. You can't be both rich AND poor at the same time, no more than you can be tall and short at the same time.

Therefore, the simplest way to diagram this stimulus is as follows:

Rich :arrow: Poor
Poor :arrow: Rich

Honest :arrow: Dishonest
Dishonest :arrow: Honest

As for your second question, it could be diagrammed either way! This would be just as valid:

Poor :arrow: Rich
Rich :arrow: Poor

We actually have a similar fluidity in written language. You could write "If you're not rich, then you're poor," OR "If you're rich, then you're not poor." They mean the same thing, right?

Does this help?
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 wisnain
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#106165
Chandler H wrote: Thu Apr 25, 2024 3:47 pm
wisnain wrote: Thu Apr 25, 2024 2:37 am Hello,

I have a quick question about the 'either A or B' logic that's been bugging me lately.

1. From what I understand, unlike how we interpret it in everyday situations, the LSAT seems to approach 'either A or B' as ‘if not A, then B’, ‘if not B, then A’, and ‘POTENTIALLY BOTH (unless explicitly stated otherwise, such as ‘not both’). How should I go about diagramming this stimulus when there isn’t any additional clarification provided?

2. Also, why doesn’t ‘either A or B’ simply translate to ‘If A, then not B’, and ‘If B, then not A’, similar to how we interpret it in everyday life? Could you help me understand why the inclusion of ‘not’ at the sufficient part is necessary?

Thank you.
Hi wisnain,

To answer your first question, diagramming this specific stimulus requires some contextual common sense. It's true that some situations can be described as "either A, or B, or both." However, in this context, we are talking about opposites: rich/poor, honest/dishonest. You can't be both rich AND poor at the same time, no more than you can be tall and short at the same time.

Therefore, the simplest way to diagram this stimulus is as follows:

Rich :arrow: Poor
Poor :arrow: Rich

Honest :arrow: Dishonest
Dishonest :arrow: Honest

As for your second question, it could be diagrammed either way! This would be just as valid:

Poor :arrow: Rich
Rich :arrow: Poor

We actually have a similar fluidity in written language. You could write "If you're not rich, then you're poor," OR "If you're rich, then you're not poor." They mean the same thing, right?

Does this help?
Thanks a lot, it was very helpful!

Regarding my second question, I wanted to clarify situations where the concept of ‘either A, or B, or both’ applies. Take for example the LSAT scenario: ‘Either strawberry or watermelon will be served today.’ It implies:

(sufficient) strawberry :arrow: (necessary) watermelon
(sufficient) watermelon :arrow: (necessary) strawberry
or both could be served.

I’m curious why I can’t diagram it as:
(sufficient) strawberry :arrow: (necessary) watermelon
(sufficient) watermelon :arrow: (necessary) strawberry

Thank you in advance for your insights!
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 Dana D
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#106174
Hey Wisnain,

In the example question for rich/poor honest/dishonest, we are presented with binary options - you can be either / or but not both.

In your example 'Either strawberry or watermelon will be served today' as you said, the option is really to serve strawberries or watermelon or both. At least one of those fruits must be served, but you could serve both.

You diagram it as

strawberry :arrow: watermelon because you know you have to serve at least one of these fruits - if you don't serve strawberries, you know watermelon is served. But because you have the option to potentially serve both, you can't diagram this as

strawberry :arrow: watermelon

because you don't actually know that just because strawberries are served, watermelons aren't. You might have both served. You could only diagram like that if the rule was "either strawberries or watermelon is served but not both."

Hope that helps!
User avatar
 wisnain
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#106237
Thank you so much!
It’s very clear now :-D


Dana D wrote: Fri Apr 26, 2024 10:29 am Hey Wisnain,

In the example question for rich/poor honest/dishonest, we are presented with binary options - you can be either / or but not both.

In your example 'Either strawberry or watermelon will be served today' as you said, the option is really to serve strawberries or watermelon or both. At least one of those fruits must be served, but you could serve both.

You diagram it as

strawberry :arrow: watermelon because you know you have to serve at least one of these fruits - if you don't serve strawberries, you know watermelon is served. But because you have the option to potentially serve both, you can't diagram this as

strawberry :arrow: watermelon

because you don't actually know that just because strawberries are served, watermelons aren't. You might have both served. You could only diagram like that if the rule was "either strawberries or watermelon is served but not both."

Hope that helps!

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