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# PT40.S3.Q25 - inflation rates will not stabilize

Free Trial Member
edited August 2016 148 karma
https://7sage.com/lsat_explanations/lsat-40-section-3-question-25/
Hoping someone can explain why the answer is D.

I understand why A, B and E are incorrect. I got down to C and D but chose C and I'll explain why.

D makes an absolute conclusion. It says, "It is therefore unavoidable that the level of vehicle safety will not be optimal." In other words, "Vehicle Safety WILL NOT (absolute) be optimal." Our stimulus however, makes no absolutely claim, instead using the word "overly optimistic (unlikely)"

I read through the Power-score forum and the admin was attempting to claim that D did not make an absolute claim. I just can't get behind this.

I realize that C ends with a conditional. But it's still a correct conditional that parallels what we see in the stimulus.

Feeling frustrated because this makes no sense!

• Member
edited August 2016 611 karma
What makes (D) better than (C) isn't the strength of the conclusion. What makes (D) better than (C) is that (C) is just not an instance of the same argument form.

The argument in the stimulus relies on modus tollens (P→Q, ~Q, therefore ~P) with one implicit premise:

P1: stabilize inflation → econ growth decrease
P2: econ growth decrease → full cooperation of world leaders
Implicit P3: ~full cooperation of world leaders
C: ~stabilize inflation

The argument in (C), however, is of the following form:

P1: optimal decision → examine all options
P2: examine all options → delay presentation
C: optimal decision → delay presentation

As you can see, there's no implicit premise in (C), and the argument doesn't rely on modus tollens at all. Rather, the argument in (C) is a hypothetical syllogism (P→Q, Q→R, therefore P→R), and this is a completely different argument form.

For completeness, here is the argument form for (D):

P1: safest vehicles possible → objective structural tests
P2: objective structural tests → huge cost overruns
Implicit P3: ~huge cost overruns
C: ~safest vehicles possible

A very quick way to see why (D) is a better answer than (C) is to note that (C) is an explicitly valid argument. However, without the implicit premise we've assumed for the stimulus and for (D), the arguments are explicitly invalid. Thus, (C) is not parallel to the stimulus.
• Member
651 karma
Ok so bare with me as I try to explain this.

The Stimulus in conditional language is this;
inflation rates stabilize-------> (Economic Growth decreases)-----> Cooperation of WL

----------------------------
The conclusion of the stimulus is inflation rates won't stabilize (negate first one)

Answer choice D is exactly the same

Produce safest vehicles possible---> conduct objective tests------>huge cost overturn

-----------------------------------
The conclusion is the negation of Produce safest vehicles possible.

As you can see the stimulus and answer choice D have a A--->B----->C relationship and both conclusions are negating the A
• Member
651 karma
So by this answer choice D and the stimulus have the same line of reasoning.
• Free Trial Member
edited August 2016 148 karma
@quinnxzhang So I understand what you're saying, but just because the author doesn't explicitly state there is an implicit premise in C) doesn't mean there isn't! It could very well be the case that a delay in presentation isn't possible. We just don't know either way because it wasn't stated. So it could exist. I don't think the fact that the implicit premise isn't stated is sufficient to rule out C)

C) does differ from the stimulus in that its conclusion ends with a conditional statement, but I'd rather my conclusion be a summarization of the transitive nature between P1 and P2 (that you can't have optimal decision without a delay in presentation), rather than an absolute as is demonstrated in D) because C) does not provide an absolute conclusion (only that it is unlikely)
• Member
edited August 2016 611 karma
@civnetn said:
So I understand what you're saying, but just because the author doesn't explicitly state there is an implicit premise in C) doesn't mean there isn't! It could very well be the case that a delay in presentation isn't possible.
This is missing the point. The point is that in order for the stimulus to be valid, we need to assume an implicit premise. However, we don't need to assume anything implicitly to make (C) valid. (C) is already valid by itself. This is a major difference between the stimulus and (C), and this is why (C) is incorrect.

In other words, taking only what's explicitly stated, the argument in the stimulus is invalid. Taking only what's explicitly stated, the argument in (C) is valid. Thus, (C) cannot be parallel.
@civnetn said:
C) does differ from the stimulus in that its conclusion ends with a conditional statement, but I'd rather my conclusion be a summarization of the transitive nature between P1 and P2 (that you can't have optimal decision without a delay in presentation), rather than an absolute as is demonstrated in D) because C) does not provide an absolute conclusion (only that it is unlikely)
This misprioritizes the importance of strength over form. The most important thing for parallel reasoning questions is that the correct answer has the same argument form. But a conditional statement has a completely different logical form than a non-conditional statement, regardless of how strongly stated the non-conditional statement is. That is to say, the conclusion of both the stimulus and (D) can be represented by a single sentence symbol in propositional logic, i.e. '~P'. However, the conclusion of (C) cannot be represented by a single sentence symbol, but must be represented with a conditional, i.e. 'P→Q'. The conclusion of (C) is formally different from the conclusion of the stimulus, and this trumps other considerations such as how strongly stated the conclusion is.
• Free Trial Member
148 karma
@quinnxzhang Ok that makes sense then. Thanks for bearing with my nitpicking. My LR is pretty good except for the 2-3 question per game like this that stump me.