To become an expert on a musical instrument, a person must practice. If people practice a musical instrument for thre...

Naz October 10, 2013

The 1st principle is diagrammed as follows:

E ==> P

not P ==> not E

The 2nd principle is diagrammed as follows:

PI3H ==> EI

not EI ==> not PI3H

From this the stimulus concludes:

EI ==> @least PI3H

not @least PI3H ==> not EI

The conclusion is just reversing the second principle (i.e. taking PI3H ==> EI to mean EI ==> PI3H) . The variables have been flipped, but not negated. Just Don't Reverse!

Looking at the diagram of the 2nd principle, someone can be an expert at a musical instrument and not have practiced three hours each day (we see this by looking at the necessary conditions of the premise and its contrapositive, EI & not PI3H, which is a viable scenario). Remember, the existence of the necessary condition tells us nothing.

So the conclusion is mistaking the necessary condition (being an expert on a musical instrument) for the sufficient condition (having practiced three hours every day). Remember that the presence of the necessary condition does not necessarily prove the existence sufficient condition. It is possible the sufficient condition is present, but it is also possible that it is not.

Answer choice (B) delineates how the conclusion does not look at the viable situation of one being an expert on a musical instrument, and yet not having practiced for three hours every day.

Hope that helps! Let me know if you have any other questions.

stephiviviana November 29, 2016

I had the same question. Thank you so much for clarifying :)

alymathieu December 10, 2018

I don't understand how the first principle is diagrammed that way, when your lessons explicitly state that if introduces a sufficient condition, and in this question the principle is if you practice three hours a day you are going to become an expert.

Jacob-R December 11, 2018

Hi @alymathieu

The way Naz has diagrammed and labeled her first and second principles above corresponds to the first and second sentences in the passage.

That is, “to become an expert on a musical instrument, a person must practice” is the “1st principle” diagrammed as E ==> P and the contrapositive.

The second sentence, that begins with “if people practice” does introduce a sufficient condition, just as you say. Naz has it labeled as the 2nd principle and it is diagrammed as PI3H ==> EI, and the contrapositive.

Does that help? Please let me know if I am not understanding your question correctly!

alymathieu December 20, 2018

But there is no word in the first sentence to indicate sufficient and necessary

Ravi December 21, 2018

@alymathieu,

The word in the first sentence that indicates a conditional relationship is "must." The word "must" introduces the necessary condition.

The first sentence states, "To become an expert on a musical instrument, a person must practice."

"Must" introduces the necessary condition, which is "practice"

The rest of the premise is in the sufficient condition

Expert - ->Practice

Does this help? Let us know if you have more questions!

Abigail-Okereke November 6, 2021

I am still confused between answer choice a and b (even though I chose b).

Ravi February 4, 2022

A doesn't work because we're told that if they practice for 3 hours a day, they will eventually become experts. Whether or not that has occurred yet is something the argument isn't concerned with, so it's not a flaw to not have that in there.

B works because practicing 3 hours per day is sufficient for everyone to become experts, but that does not mean that it is necessary for everyone. There could be musical geniuses who only need an hour or two per day to become experts.