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Author Topic: Taking a Logic Course  (Read 2706 times)

r_poster

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Re: Taking a Logic Course
« Reply #10 on: March 21, 2004, 10:47:55 AM »
The logic games bible.  Go buy it.  The people on this board won't take the LSATs for you.

Louder Than Bombs

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Re: Taking a Logic Course
« Reply #11 on: March 21, 2004, 10:48:40 AM »
"Only if the electorate is moral and intelligent will a democracy function well."

First, you change it to--as you should know from your logic course--if/then statements.

"If a democracy is functioning well, then the electorate is moral and intelligent."

Okay, while I agree with the way you have sort of 'switched this around', I think that this case was not a good example to use as it can be a bit confusing.

The reason why what you did was lawful was because the first statement is actually a bi-conditional (if and only if) - the key word being 'ONLY if the electorate...'

Symbolically, you did this...

A + B <---> C

then converted this to...

C ---> A + B

HOWEVER, it is very important to realize that this conversion is UNLAWFUL for regular conditional statemnets, i.e. the ones that are not of the form 'if and ONLY if'...

For example, if the original statement read, 'If the electorate is moral and intelligent, then a democracy will function well', this connversion would be unlawful...

Symbolically...

A + B ---> C

IS NOT EQUIVALENT TO

C ---> A + B

Why? Well, let's imagine that the first statement were true - that is, if an electorate is moral and intelligent, then a democracy will work well.  However, we must realize that this is ONLY ONE way a democracy could work well (that is, by having a moral an intelligent electorate). Another way a democracy could work well would be to have an unintelligent, immoral electorate who were so stupid that, by some twist of fate, they always chose the best candidate (this assertion is obviously completely ludicrous, and the whole example begs the question of what does 'well' mean when speaking about how democracies function, but you get the idea).

So, after all this I would say that it is best to refrain from taking a logic course or attempting to analyze LR questions using symbolic logic (for the most part). It can be very confusing, and also time consuming - and as we all know, time is of the essence when taking the LSAT...

Chris

Victor

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Re: Taking a Logic Course
« Reply #12 on: March 21, 2004, 12:18:28 PM »
The logic games bible.  Go buy it.  The people on this board won't take the LSATs for you.

Logic Games Bible can be used for the Logical Reasoning section ?






LawEcon

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Re: Taking a Logic Course
« Reply #13 on: March 25, 2004, 12:01:22 AM »
"Only if the electorate is moral and intelligent will a democracy function well."

First, you change it to--as you should know from your logic course--if/then statements.

"If a democracy is functioning well, then the electorate is moral and intelligent."

Okay, while I agree with the way you have sort of 'switched this around', I think that this case was not a good example to use as it can be a bit confusing.

The reason why what you did was lawful was because the first statement is actually a bi-conditional (if and only if) - the key word being 'ONLY if the electorate...'

Symbolically, you did this...

A + B <---> C

then converted this to...

C ---> A + B

You make good points about the biconditional.  However, dsds3581's example is correct.

"Only if the electorate is moral and intelligent will a democracy function well"

translates to:

"If a democracy functions well, then the electorate is moral and intelligent,"

i.e., D --> M and I.

"If and only if the electorate is moral and intelligent will a democracy function well"

translates to:

"A democracy functions well if and only if the electorate is moral and intelligent,"

i.e., D <--> M and I.

Since the example does not begin with "if and only if," but rather, "only if," it should not be treated as a biconditional statement.