#25 - Marianne is a professional chess player who hums

[kcho10]

Hi,

Could someone clarify why C is incorrect? Also, how would we diagram this answer choice for more clarity? I always have trouble diagramming 'Not all' statements, because it implies none or some. Thank you!

[nicholaspavic]

Hi kcho,

"Not all" is really a term reserved for formal logic which is tested very little on the modern LSAT. Formal logic includes less-than-certain terms, such as "some," "most," "usually," "not all," etc...

Everything that you know about diagramming conditional logic can be applied to formal logic, but make sure to take a lot of care with making connections between terms in chain relationships and taking the contrapositives of formal logic statements (there is no contrapositive when a formal logic statement uses the term "not all" or "some" or "most".0

With that not, let's look at the stimulus. Marianne's argument goes:

unaware involuntary responsibility

Answer Option (C) pulls this bs Shell Game with it's logic by saying involuntary (not all) unaware.

See the difference? If it had been the other way around, that would attack the first sufficient in Marianne's argument and that would effectively weaken her argument, but instead it's reversing the logic which does not effect the conditional argument she's making. That's why it's wrong.

Thanks for the great question and let us know if this helped!

[LSAT2018]

Unaware → Involuntary → Not Responsible

So Answer (D) is taking the conditional statement above and showing that the necessary condition (involuntary) is not met, thus weakening the statement?

To clarify for Answer (C), do I read this as conditional or formal logic? I always get confused on these!
Involuntary → Aware or
Involuntary (Not All) → Unaware (Mistaken Reversal)

[Francis O'Rourke]

Answer choice (D) tells us Marianne can, with some amount of effort, become aware of her humming and can control it. I understand a "controllable" action as the opposite of an involuntary one, so this answer choice tells me that Marianne could get rid of both the sufficient conditions that led her to believe that she should not be held responsible for her action.

Answer choice (C) tells us that it is not true that ALL involuntary actions are ones which you are unaware of.
That is, involuntary unaware is not always true.

We can also diagram that statement as involuntary some aware .

[nicizle]

Can someone provide a clearer explanation regarding what exactly makes C incorrect?

[nicizle]

Answer choice (D) tells us Marianne can, with some amount of effort, become aware of her humming and can control it. I understand a "controllable" action as the opposite of an involuntary one, so this answer choice tells me that Marianne could get rid of both the sufficient conditions that led her to believe that she should not be held responsible for her action.

Answer choice (C) tells us that it is not true that ALL involuntary actions are ones which you are unaware of.
That is, involuntary unaware is not always true.

We can also diagram that statement as involuntary some aware .

If C tells us that's not true all involuntary actions are those you're unaware of, thus contradicting/refuting the points made by Marianne, then how is that not a weakener?

[Dave Killoran]

It actually doesn't refute Marianne's point. The answer says that not all of a person’s involuntary actions are actions of which that person is unaware. How do we know that this applies specifically to Marianne's humming? She could be unaware of it but then aware of other, different involuntary actions. There doesn't have to be overlap here. A very clever wrong answer.

Side note: in answers like this where it seems for sure to you that it also weakens, ask yourself, "What reason would LSAC have for saying this is wrong?" The more you think like the test makers, the better you will be.

Thanks!

[LaurenMerm]

To Nicizle's point, even if C did refute all of Marianne's points, would that still point to C being wrong because weaken answers should not completely destroy the argument -- they should just make the argument's conclusion less likely.

[Jeff Wren]

Hi Lauren,

A correct answer to a Weaken question can weaken the argument in theory anywhere from 1-100%, so while the correct answer a Weaken answer does not need to 100% destroy the argument, it's completely fine if it does. In other words, there's no such thing as an answer being "too strong" for a Weaken question or an answer weakening the argument too much.

If Answer C did refute all of Marianne's points, it would be the correct answer. The problem is that, as it is written, it does not refute any of her points. Just because a person can be aware of some involuntary actions doesn't mean that Marianne's humming isn't involuntary. It may be that her humming is one of the involuntary actions of which people would not be aware.

In formal logic, "not all" means "some are not."