"Unless" statements

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earlyfrost
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"Unless" statements

Postby earlyfrost » Sun Mar 19, 2017 5:16 pm

I'm getting two different versions of how to interpret "Unless" statements.


The Manhattan LR book interprets them this way (4th edition, page 380-383):

Unless the filed dries, the game cannot be played.
-dries ---> -game played

The PowerScore LG Bible interprets them this way (2015, page 59):

Unless you study, you cannot get an A+.
A+ ---> study


Are the statements interpreted different when doing LR vs. LG? Does it matter which method is used since their contrapositives would still reflect either method used? For example, the contrapositive of the last statement would be -study ---> -A+, which I would have gotten anyway if I used Manhattan's method of interpreting "Unless" statements.

Thank you for your help.

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lymenheimer
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Joined: Sat Jul 04, 2015 1:54 am

Re: "Unless" statements

Postby lymenheimer » Sun Mar 19, 2017 6:20 pm

The point is that they're the same. It doesn't matter how you interpret them because the contrapositive is going to be valid, regardless of which way you start it.

ie. the contrapositive for the first one is

game played --> field dries ; which I guess is the way Powerscore interprets

judill
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Joined: Fri Oct 28, 2016 3:13 pm

Re: "Unless" statements

Postby judill » Sun Mar 19, 2017 7:07 pm

When I was studying, I would read "unless" as "if not". For example, "Unless you study, you cannot get an A+" becomes "If you do not study, you cannot get an A+".

This would be "-study -> -A+", the contrapositive of which would be "A+ -> study".

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Sprout
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Re: "Unless" statements

Postby Sprout » Sun Mar 19, 2017 7:20 pm

earlyfrost wrote:I'm getting two different versions of how to interpret "Unless" statements.


The Manhattan LR book interprets them this way (4th edition, page 380-383):

Unless the filed dries, the game cannot be played.
-dries ---> -game played

The PowerScore LG Bible interprets them this way (2015, page 59):

Unless you study, you cannot get an A+.
A+ ---> study


Are the statements interpreted different when doing LR vs. LG? Does it matter which method is used since their contrapositives would still reflect either method used? For example, the contrapositive of the last statement would be -study ---> -A+, which I would have gotten anyway if I used Manhattan's method of interpreting "Unless" statements.

Thank you for your help.


The contrapositive is the same.

judill wrote:When I was studying, I would read "unless" as "if not". For example, "Unless you study, you cannot get an A+" becomes "If you do not study, you cannot get an A+".

This would be "-study -> -A+", the contrapositive of which would be "A+ -> study".


This method was useful for me personally when taking formal logic in college, during LR and LG on the lsat (most LG), and continues actually to be something I need to do frequently... Translating "but for" and "unless" statements into whatever makes the most practical sense to you given the context will help prevent answering with / getting mixed up with logical fallacies. It helped for me. Gl!

Blueprint Brett
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Joined: Wed Mar 08, 2017 10:22 pm

Re: "Unless" statements

Postby Blueprint Brett » Wed Mar 22, 2017 3:12 pm

Either way the diagram means the same thing. I recommend swapping "unless" for if not, because it's usually the most straightforward and easy to understand. "If" statements are the easiest statements to diagram, so turning these into if statements can be a huge help. Same goes for the words "except," "without," and "until"




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