LSATMax Inaccurate?


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LSATMax Inaccurate?

Postby WinstinSmithsGhost » Mon Apr 24, 2017 2:37 pm

I'm a Computer Science major who is interested in improving my ability to reason--so I decided to download the app LSATMax. In the first video for logical reasoning around the 35 minute mark, the narrator uses the following example:

1. Anyone named Sue is a girl.
2. X is named Sue.
3. X is a girl.

Initially the narrator labels this argument valid--but then the song A Boy Named Sue by Johnny Cash starts playing, and then the narrator jokingly says but wait a minute, a boy can be named Sue! Therefore, this argument is actually flawed! And then the narrator crosses out "valid argument" and replaces it with "flawed argument". He explains that "The problem with the second example here is that the argument is invalid because of a false premise".

From what I understand, this is patently incorrect. When one says an argument is valid they're referring to its logical structure; and when one says that an argument is unsound, they're saying that the logical structure is invalid or the premises are untrue. For an argument to be sound the premises need to be true and the logic valid.

So in the example used, the argument is indeed valid it's just unsound. This is from what I understand based on listening to and reading philosophy--but you don't have to take my word for it: here's a source that agrees with me,

"A deductive argument is said to be valid if and only if it takes a form that makes it impossible for the premises to be true and the conclusion nevertheless to be false. Otherwise, a deductive argument is said to be invalid.

A deductive argument is sound if and only if it is both valid, and all of its premises are actually true. Otherwise, a deductive argument is unsound."

So this raises the question, does the creator of this app not know what he's talking about or does the LSAT use idiosyncratic terminology?
Last edited by WinstinSmithsGhost on Mon Apr 24, 2017 3:39 pm, edited 1 time in total.

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Re: LSATMax Inaccurate?

Postby MediocreAtBest » Mon Apr 24, 2017 2:54 pm

It's valid. If the LSAT says "If your name is Sue, then you're a girl" then that's that, it's valid even if we know in real life that potentially there could be a boy named sue. Sue-->Girl, X-->Sue, so X-->Girl.

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Re: LSATMax Inaccurate?

Postby Future Ex-Engineer » Mon Apr 24, 2017 3:16 pm

This would indicate to me that LSATMax is a terrible LSAT study resource.

Drop it before it teaches you bad/false information and habits.

The LSAT doesn't screw around with false premises and such. The whole point is it doesn't test your external knowledge - just your understanding of the reasoning structures and such present in the arguments.

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