Q10 - Tires may be either underinflated

[sharrin7]

For this question, I managed to eliminate A, C, and E fairly easily, but struggled in deciding between B and D. Ultimately, I chose wrong. I see why B can be considered incorrect, however I fail to see why D is correct.

What has not been proven (based on the word "assuming"): underinflation or overinflation of tires harms their tread.

But, how does the argument "reject" the possibility that this is true?

Thanks in advance.

[ManhattanPrepLSAT1]

Thanks for bringing this question to the forum!

This argument contains a fairly common reasoning error. It treats the failure to disprove a claim as proof that the claim is true. But we know that not proving something to be false, doesn't mean that it's true.

By analogy - I can't prove that nuclear power is dangerous, but that doesn't mean that it's safe.

Answer choice (D) describes this error in reasoning. The argument does reject the possibility that underinflation and overinflation do not harm tire tread, on the grounds that no one has proven that they do not harm tire tread.

(A) describes circular reasoning, but the conclusion does not merely restate a premise.
(B) relies on an additional assumption. Just because no one has proven that underinflation and overinflation do not harm tire tread, doesn't mean that this is not in principle susceptible to proof. Maybe it is susceptible to proof and we just need to assign someone to go investigate!
(C) is irrelevant. Sure the argument does fail to specify this, but the conclusion doesn't need to have any such specification in order for the conclusion to follow.
(E) is true, but is not a flaw. Why would we expect the argument to do this?

Does that answer your question?

[mcrittell]

Can someone explain what B means? I'm getting lost in the words.

[qccgraphix]

Mshermn seems to have nailed it:

(B) relies on an additional assumption. Just because no one has proven that underinflation and overinflation do not harm tire tread, doesn't mean that this is not in principle susceptible to proof. Maybe it is susceptible to proof and we just need to assign someone to go investigate!

To add:

What B does is it implicitly states that 'assuming that underinflation or overinflation of tires harms their tread' is a principle that is not susceptible to proof, and that the argument overlooks that even thought this is the case, it may still be false.

What you have to pay attention to here is that the answer choice does not accurately depict what is occurring in the stimulus. The answer choice ascribes a flawed definition to the speaker's concluding remarks in the stimulus, by assuming it is not susceptible to proof. Therefore, this answer choice does not most accurately describe a flaw in the argument's reasoning.

[joseph.m.kirby]

Generally, the flaw committed in this question relates to "Treating a Failure to Prove a Claim as Proof of the Denial of That Claim."

Argument:
Cannot prove: ~Harm
Therefore: Harm (or ~Harm = False)

(B) and (D) are the best answers

(B) is wrong because the author doesn't "overlook" the flaw in (B); the author commits the flaw in (B). (B) basically says, "The argument overlooks that what is not in principle susceptible to proof (~Harm) might be false (~Harm = False).

(D) is what we want. By putting forward the assumption in (B), the argument REJECTS that what has not been proven (~harm) is nevertheless true (~harm). By putting forward (B), the argument has rejected an outcome whereby it's possible that ~harm = true.

[WaltGrace1983]

Generally, the flaw committed in this question relates to "Treating a Failure to Prove a Claim as Proof of the Denial of That Claim."

Argument:
Cannot prove: ~Harm
Therefore: Harm (or ~Harm = False)

(B) and (D) are the best answers

(B) is wrong because the author doesn't "overlook" the flaw in (B); the author commits the flaw in (B). (B) basically says, "The argument overlooks that what is not in principle susceptible to proof (~Harm) might be false (~Harm = False).

I'd say that is what ALMOST happens but (B) is actually out of scope.

(B) is a really tempting answer choice because it IS so close. However, the argument does NOT have evidence about something that is not susceptible to proof. Instead, the argument has evidence about something that has not been proven.

It says that ~(Harm) has not been proven. It does not say that ~(Harm) cannot be proven. There is a big difference.

(B) would be right had the argument looked like this:
We are pretty safe in assuming that underinflation or overinflation of tires harms their tread. After all, we cannot prove that these do not harm tire tread.

(D) is right because it more accurately expresses the flaw. However, the reason why it is hard is probably because there are so many negatives happening in the argument.

Hope that helps

[cyt5015]

I disagree with above in interpreting "no one has been able to show" into "no evidence has been shown", because just think about the following example: I was not able to finish that task v. I didn't finish that task. The first sentence implies my inability leads to task incomplete, but the second does not.
The issue whether we can treat "not susceptible to proof" equally as "no one has been able to show" is open to debate. If we can treat them as equal, then the author actually did not overlook but treat what is not susceptible to proof as likely being false. Can any geek or expert clarify that please? Thanks a lot!

[maryadkins]

On the LSAT, this same flaw is expressed in various ways:

hasn't been shown to be false --> is true

no one has been able to prove false --> is true

I see what you're getting at, which is that in the first example, maybe people haven't in TRIED. In the second, presumably they have. This would seem to make the second one a better argument.

But LSAT-wise it's not. It's the same flaw: Just because something hasn't been disproven doesn't make it true, whether or not people have done their best and failed or not tried at all.

As for "not susceptible to proof," we don't know that. Even if people haven't been able to figure it out that doesn't make it unprovable. Maybe the people who were trying were sloppy, or didn't know what they were doing.

[cyt5015]

Now I see it. So in LSAT, "no one has been able to prove"="no evidence has been shown"="no one has shown any evidence that", but not equal to "not easy (susceptible) to prove". Thank you for your insight!

[roflcoptersoisoi]

Flaw: Takes for granted that something must be true because there is no evidence that show that it is false.

(A) No circular reasoning here
(B) Descriptively inaccurate. Just because we have no evidence showing that the under/over inflation of tries harms their treads doesn't mean they are not in principle susceptible to proof.
(C) Descriptively accurate but not a flaw in the argument
(D) Bingo
(E) same as C