The only vehicles that have high resale values are those that are well maintained. Thus any well-maintained vehicle h...

Irene on June 30, 2019

What is the flaw here?

I chose A because I thought the flaw was that the argument presupposed what it sends out to prove but now that I see that's not correct I'm wondering what the aw here is.

1 Reply

Shunhe on December 27, 2019

Hi @Irene-Vera,

First, we see that this is a match the flaw question, and so we need to figure out what's wrong with the argument's reasoning and then match it. The confusing nature of the wording makes it a bit hard to follow. Note that we can rewrite "The only vehicles with high resale are those that are well maintained" as "Only well maintained vehicles have a high resale value," or in other words, "Only if a vehicle is well maintained, will it have a high resale value." Recall that we can diagram "X only if Y" as Y - > X. Thus, we can diagram the premise here as:

High resale value - > Well-maintained

We then conclude from this premise that

Well maintained - > High resale value.

This is an illegal reversal; we can't just switch two sides of the conditional like that. We need an answer choice that does the same, and skimming the answer choices, this is exactly what (D) does. If we diagram (D), we get

City dweller - > Prefer W to TJ

Prefer W to TJ - > City dweller

Which is exactly the same kind of flaw.

(A) is wrong because it's a different flaw in (A). In (A), the issue is that it concludes that no plant needs pruning because none have been pruned before. In other words, it's not the reversal we need, it instead is an argument based on past practices that doesn't necessarily hold true today. Hope this helps!