#25 - Philosopher: The eighteenth-century thesis that

[PB410]

Hi,

I'm working through your Logical Reasoning Question Type Training book. I have a question regarding number 34 in the Method of Reasoning section. It is the question that is about the 18th century thesis on absolute motion follwoed by a counter premise, and a conclusion. The answer is listed as C, yet I was thrown off because of the wording, specifically "premise" in the answer, as in "relying on the authority of an expert to support a premise". Isn't the author relying on the authority of an expert to support a CONCLUSION? Isn't the conclusion of the author in the stimulus, "Since a thesis that is incoherent cannot be accepted as a description of reality, motion cannot be absolute."? I am confused why the correct answer would define it as a premise.

[Jonathan Evans]

Hi, PB410,

Good question. You are correct that a premise by definition supports a conclusion. Further, you are also correct that this appeal to authority does (indirectly) support the main conclusion that "motion cannot be absolute." However, you may be familiar with the concept of a "subordinate conclusion," an intermediate step supported by other premises that in turn supports a main conclusion. A subordinate conclusion is itself a form of premise because it is a proposition from which another conclusion is inferred.

For this problem, the LSAT has chosen to eschew the term "subordinate conclusion" in favor of "premise," which is the source of confusion here. The appeal to the authority of the physicist does back up the premise that the absolute motion thesis is incoherent. The author then uses this incoherence as a premise to support the main conclusion that motion is not absolute.

(1) Physicist says thesis incoherent.
(2) Thesis is incoherent.
(3) Incoherent stuff can't be accepted as valid.
(4) Motion not absolute.

Statements (2) and (3) above are premises used to justify the conclusion (4). Statement (2) is also a subordinate conclusion that the author infers from statement (1).

I hope this helps! Please follow up with further questions!

[PB410]

Thanks for the response.

So just to clarify, the author is relying on the well-respected physicist's claim that the thesis is incoherent(premise), and subsequently the author restates that idea, that the thesis is incoherent as a premise to support the conclusion that motion cannot be absolute. I must have failed to identify the premise in the final sentence, therefore only reading the premise and conclusion as a lone conclusion.

[Jonathan Evans]

Precisely! Well done PB410.

[sherrilynm]

Can someone please explain why A is not correct? Yes, the philosopher does say "well-respected physicist," but the argument relies on the use of the word "incoherent." Wouldn't that count as trying to persuade by "mere use of technical terminology," trying to win the argument on the reliance of a single word?

[Adam Tyson]

This argument isn't based solely on the use of technical terminology, sherrilynm. I'm not sure "incoherent" qualifies as a technical term here, but even if it does, the argument goes further than just relying on that word. Rather, the author uses that term, plus the opinion of an expert, together with his own additional premise (that incoherent theses cannot be accepted), all together to conclude that thesis is wrong.

I'm not sure what an argument described by answer A would look like. Something like "you say that the satellite will get closer to the Earth soon, but that cannot be true because it is already at its perihelion," perhaps. There, I have relied on a technical term and given no other information. You are supposed to believe me only because I threw some jargon at you. Or perhaps, "Some people say that geothermal energy is making a comeback, and this must be true because of the fenacinerity of the claim." Here, I am just trying to baffle you with b.s. in the form of a fancy sounding word that is actually a nonsense word. The argument here didn't do that, but relied on an expert much more than on any jargon or other special terminology.

Let us know if that helped!

[sherrilynm]

Yes, that makes a lot more sense now. Thanks!

[SwanQueen]

Hello Powerscore,

Can someone please explain why the answer choices are incorrect, and also re-phrase why (C) is the correct a.c?

Thank you in advance!

[Jeremy Press]

Hi SwanQueen,

Here, answer choice A is incorrect because part of what the author relies on is the say-so of a well-respected physicist that the thesis about motion is incoherent. That's not "mere use of technical terminology," rather that's also "use of the authority of a respected physicist" (as part of the reason to believe the argument. So, there's more to the argument than answer choice A says.

Answer choice B is incorrect because the author doesn't "use" any "experimental results" at all. Rather, the author uses a physicist's claim about the incoherence of a theory, plus a principle about incoherent theses, to get to the conclusion. No experimental results to be found!

Answer choice C is correct, because (as mentioned above) the author is solely relying on a "well-respected" physicist's claim about the incoherence of a theory (whether that claim about incoherence is right or wrong, we don't know) to derive the conclusion. Thus, it's an argument relying on the physicist's authority.

Answer choice D is incorrect for the same reason as answer choice B, because the argument does not use (or even refer to) observations made under experimental conditions.

Answer choice E is incorrect because the premises nowhere refer to what is happening in "one" particular "region" of space.

I hope this helps!

Jeremy