#25- The judgment that an artist is great always rests on

[smile22]

What is the flaw in this stimulus? Is it a mistaken reversal? Below is the diagram that I was able to come up with:

Artist great series of great works
Conclusion: series of great works artist great


For answer A, is the below diagram correct?

artist great series of great works
Conclusion: series of great works artist great

[KelseyWoods]

Hi smile22!

The flaw here isn't quite a mistaken reversal. It's a little more subtle than that.

You are correct that the author's first statement should be diagrammed:

Artist great Series of great works

The flaw comes in when the author interprets that to mean that if an artist is great then ALL that means is that he has a series of great works. Essentially, the author has assumed that one thing that is necessary is everything that is necessary. The author is saying that if an author is great, we only know about his past works and therefore can make no predictions about future works. Couldn't it also be true that if someone is a great artist, you know that any future works will be great as well? Just because you have one necessary condition does not mean that it is the ONLY necessary condition.

Answer choice (A) follows these same lines. The author first states that if you know someone has a cold, then you must observe symptoms:

Know someone has cold Observe cold symptoms

The author then interprets that to mean that if you have a cold, all you know is that you have observed cold symptoms and you can make no predictions about future symptoms that may appear. Of course, this is flawed as our stimulus is. Therefore, answer choice (A) is parallel to our stimulus.

Hope this helps!

Best,
Kelsey

[LSAT2018]

I read your explanation for the correct answer but while there may be more than one necessary conditions, I kept thinking about the shift from the present to the past. Wouldn't that constitute another reasoning error such as a time shift error?

[Francis O'Rourke]

Hi LSAT2018,

Can you describe to us the time shift from present to past that you spotted and why you believe that it makes the argument flawed?

[StephLewis13]

Hello,

Is the reason that Answer C is incorrect because of the statement, "No one can be infected by the same cold virus twice?" This means that we can, in fact, predict something about the future. Not which viruses they WILL be susceptible to in the future, but which virus(es) they WILL NOT be susceptible to in the future (i.e. ones they have already been infected by).

Thanks for your help.

[Robert Carroll]

Steph,

That would mean that answer choice (C) involves a similar problem to the stimulus, which wouldn't be the reason it's wrong.

Instead, the structure of the stimulus is something like "You can only tell whether a thing has a quality based on the past, so possession of a quality by a thing should not validate any predictions about the future." In answer choice (C), there is no quality inferred based solely on the past, so answer choice (C) is incorrect.


Robert Carroll

[bruceg]

I also chose "C" (different viruses) because I couldn't quite grok the grammar in "A" (what does it mean you can't predict future symptoms"? Should have been "cant predict future symptoms will be similar").

But now I see the problem. There IS no logical flaw in "C". It's true, you can't predict if you'll be susceptible to Virus X in the future because you were susceptible to Virus Y today. If there is a logical flaw in this argument, it's not the same logical flaw as the one in the passage.

[Rachael Wilkenfeld]

Hi Bruce,

Good question! You did a good job of noting that answer choice (C) is different than the stimulus. The issue in the passage, and in answer choice (A), is that the arguments state that you can't know anything about the future based on the past. So if an artist is great, we know only that they have a body of work that is great. We can't use that to show that it might be more likely that future works will also be good. That's not proven by the stimulus. There are reasons to think that maybe artists who are great (or have a series of great works) have some talent that might predict future goodness. The same flaw appears in answer choice (A). The author states that the only way to know that someone has a cold is to observe their symptoms. So just seeing their symptoms of a cold tells you nothing about future symptoms. However, the error here is the same. Having a cold would possibly suggest that you are likely to still have sniffles a day later, or that you could have sinus pressure or any number of things.

Hope that helps!