PT80.S4.Q22 - scientists once believed that

brigitte

The correct answer to this question is information that would help to evaluate the argument in the stimulus. If the information is taken to one extreme, it will strengthen the argument, and if the information is taken to the other extreme, it will weaken the argument. Under this standard, why isn't (D) correct?

The argument breaks down as follows, imo:

Premise: A nearly complete skeleton of an earlier dinosaur that was not a T.Rex had the T.Rex characteristics (big head, small arms, long legs), but was much smaller in size and lighter than the T.Rex.

Conclusion: The T.Rex's features (big head, small arms, long legs) did not develop in order to accommodate the size and weight of the T.Rex.

I understand why (B) is a question that would help evaluate the argument, but why isn't (D) considered information helpful to evaluate the argument?

If the earlier dinosaur is NOT related to the T.Rex, then wouldn't that weaken the argument by leaving it more vulnerable to the objection that some difference between that dino and the T.Rex explains the counterexample away? And imagine if the dinosaur was almost exactly the same as a T.Rex (so extremely closely related) -- wouldn't that strengthen the argument by strengthening the relevance of the counterexample and making it harder to distinguish it?

Let's go a little bit outside the stimulus to explore this issue -- if we had found a mammal skeleton that had the T.Rex head, arm, and leg characteristics, but the mammal was tiny, would that evidence be just as powerful as the skeleton evidence in the stimulus? If not, then doesn't that prove the relatedness of the skeleton specie and the T. Rex IS helpful to evaluating the argument? And if the answer is yes (that a mammal skeleton would be just as powerful as a dino skeleton as evidence for the conclusion), how?

Thank you for any thoughts.

brigitte

bumping. Thank you for any thoughts on this problem.

Zachary_P

I'll take a stab at it... The key to this question is understanding why the T Rex has the features it does. Answer choice B helps us answer this question by giving us an answer to a flaw in the original argument. If the new bones found were of a dinosaur that was still growing, then we can leave the original hypothesis in tact because the developing dinosaur could have developed the characteristics in question for the same reasons as the T Rex. IF, however, the new bones are from a fully developed dinosaur, then we can presume that the original hypothesis is not entirely correct, i.e. the conclusion. AC B is the only AC that helps give us a definitive evaluation of the soundness of the argument.

Now for answer choice D. Quite simply, we don't care if it's related to the T Rex or not. It has no bearing on the overall purpose of an oversized head, long hind legs, etc.

You mention that, "If the earlier dinosaur is NOT related to the T.Rex, then wouldn't that weaken the argument by leaving it more vulnerable to the objection that some difference between that dino and the T.Rex explains the counterexample away?" But even if we have the answer to this question, we are left to ask, "What is it that explains this supposed counterexample?" It is presumable that the answer could be, "To accommodate the great size and weight of this dinosaur as well." But even if that is not the answer, it comes down to the fact that we still simply do not know how to evaluate the newly found skeleton because we don't if it is actually as big as the T Rex or not. Knowing the age of the newly found specimen is the only question we need answered to help us close that gap. For this reason, AC D does not help us evaluate the argument.

Let me know if this made sense!