The tidal range at a particular location is the difference in height

Question

The tidal range at a particular location is the difference in height between high tide and low tide. Tidal studies have shown that one of the greatest tidal ranges in the world is found in the Bay of Fundy and reaches more than seventeen meters. Since the only forces involved in inducing the tides are the sun’s and moon’s gravity, the magnitudes of tidal ranges also must be explained entirely by gravitational forces.

Which one of the following most accurately describes a flaw in the reasoning above?

(A) It gives only one example of a tidal range
(B) It fails to consider that the size of a tidal range could be affected by the conditions in which gravitational forces act
(C) It does not consider the possibility that low tides are measured in a different way than are hightides
(D) It presumes, without providing warrant, that most activity within the world’s oceans is a result of an interplay of gravitational forces
(E) It does not differentiate between the tidal effect of the sun and the tidal effect of the moon

Source: LSAT and CR Archive

u1983 · Answer

Option A: Incorrect  : This is more a neutral statement. It does not contribute much to our concern- how the magnitude of the tidal range can be explained.

Option B: Correct   : The BOF has unusually high TR. But the TR is dependent on Sun & Moon's GravF. But is there any factors geological, seasonal, weather , and/or environmental at the area of BOF, that contribute to the higher TR ? This option directly points to that possibility.

Option C: Incorrect  : The way of measuring of tides is not the concern of the passage. We are rather interested in the measured value of those and the difference of those values constitute the value of tidal range( our main concern)

Option D: Incorrect  : Oceans activity is a information that is brought from outside ( not related to passage)

Option E: Incorrect  : The difference in tidal effect of sun & moon will not have difference in the tidal range as a whole .

sandman13 · Answer

Reasoning: gravity is the ONLY force which is responsible for tides. This doesn’t imply that they explain EVERYTHING about tides. <- This is the flaw in the reasoning. It ignores other factors such as wind, climate change, etc. 
 
Answer: B

reviewtattantat · Answer

Official answer:
If the magnitudes of tidal ranges are explained entirely by gravitational forces, then wouldn’t tidal ranges be identical everywhere? Why would the sun’s gravity, and/or the moon’s gravity, act differently in the Bay of Fundy? Something’s fishy here. The argument might look logical, but there’s a bait and switch happening here. We have a premise that says, “The only forces involved in inducing the tides are the sun’s and moon’s gravity,” and a conclusion that says tidal ranges must be entirely explained by gravitational forces. The problem with this is that “inducing” just means “starting.” So this argument basically pulls this switch on us: “Since childbirth can be induced by jumping on a trampoline, childbirth is entirely explained by jumping on a trampoline.” Really? Nah, didn’t think so. I’m not sure how to articulate the flaw precisely, but I do know it has something to do with “inducing” and “entirely explained” not being the same thing.

A) Uh, no. More examples might be nice, but this isn’t what we’re looking for and I wouldn’t call this a “flaw,” per se.
B) This could be it. What’s special about the Bay of Fundy? I don’t know. But maybe the beach is extremely steep, or the bay is extremely shallow, or something, and those are “the conditions in which gravitational forces act” to create such an extreme tidal range. This one’s a keeper.
C) Well, the argument definitely didn’t consider this possibility. But it also didn’t consider the possibility that we don’t give a **** whether it considered the possibility of quite a lot of things, including exactly how things are measured. This just isn’t the point.
D) Does the argument actually do this? For example, does it presume that the mating cry of a Blue Whale in heat (do they go into heat? let’s pretend) is a result of the interplay of gravitational forces? Nah, I don’t think it did.E) Did the argument really need to do this? I don’t see why it would need to, if it was going to use the very broad “gravitational forces” in the conclusion. This is beside the point.
The best answer is B.

VerbalBot · Answer

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The tidal range at a particular location is the difference in height

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