Self-study
Scientists once believed that the oversized head, long hind legs, and tiny forelimbs that characterized . █████████████ ███ █████████ ██ █████ ██ ███████████ ███ █████ ████ ███ ██████ ██ ████ ███████████ █████████ ████████ ████ ██████ ████ ███ ██ ██████████ ███ ██████ ████████ ████████ ██ ██ ███████ ████████ ███ ████████ ████ ███████████ ████ ████████ ███ ███ ██████████████ ██ ███ ████████ ███ ███ █████████ ███ ████ ███ █████████████ ███ ███████
Summarize Argument: Phenomenon-Hypothesis
The author tells us that scientists used to believe some of the T. rex's distinctive features, like its oversized head and small forelimbs, were adaptations to accommodate its large size and weight. This is a causal theory: the reason behind the development of these features was the T. rex's size. More recently, a skeleton has been discovered of a dinosaur that lived earlier than T. rex and was much smaller and lighter, but had the same characteristic features. Based on this discovery, which seems to suggest that the T. Rex's characteristic features can occur even without large size and weight, the author concludes that the scientists' earlier theory has to be abandoned. In other words, the author concludes that the T. Rex's large size and weight were not the driving factors behind the development of its characteristic features.
Points to Evaluate
Notice that the author assumes we can legitimately compare the T. Rex and the newly discovered dinosaur, and that there are no factors that would make such a comparison impossible. But the author's argument is based only on a single specimen, which we don't necessarily know much about. As we evaluate this argument, it would be useful to know if there are any unusual circumstances or traits of this specimen that might change our interpretation of the data. It would also be useful to know if the same traits can develop in different species for different reasons: in other words, if it is still possible for the T. Rex to have developed these traits because of its size and weight, even if the earlier dinosaur developed them for some other reason. The author assumes this is impossible.
22.
The answer to which one ██ ███ █████████ █████████ █████ ████ ████ ██ ██████████ ███ █████████
a
Was the ratio ██ ███ ████ ████ ██ ███ ████████ ██████████ ████████ ██ ███ ████ ████ ███ ████ ██ ████ ███ ██ ████
This doesn’t help us. The premises tell us explicitly that the skeleton shares "the characteristic T. rex features," including an oversized head. Because of this statement, even if the answer to this question about head-to-body ratio is "no," we would still have to accept that, even if the head-to-body ratio isn't exactly the same in this dinosaur versus the T. Rex, its features still count as "characteristic" of the T. Rex. And if the answer to the question is "yes," then we would just be confirming something we know already: this dinosaur and the T. Rex share certain features. In other words, answering this question doesn't give us any useful information for evaluating the argument.
Illusory inconsistency
Illusory inconsistency
Answer is attractive because it seems to (but doesn't actually) contradict the premises or conclusion.
b
At what stage ██ ███ ████ ███ ███ ████████ ██████████ ████████ ████
This would be useful in evaluating the argument. If the skeleton is a dinosaur that died as a juvenile, then perhaps that dinosaur would eventually have grown to a great size. This would then undermine the author's argument, which assumes that this skeleton shows that T. rex features weren’t size adaptations.
Alternate explanation
Alternate explanation
Weaken: Introduce or support an alternate explanation for a phenomenon.
Strengthen: Helps to eliminate an alternate explanation for a phenomenon.
c
Was T. rex ███ ███████ ███ ████████ ███████████ █████████
We don’t care if T. rex was the single largest and heaviest prehistoric predator. We just want to know whether its size and weight caused it to develop particular features or not. Whether or not there were larger predators, possibly with different adaptations, is irrelevant.
d
Was the species ██ █████ ███ ████████ ██████████ ████████ ████████ ███████ ██ ██ ████
This doesn't help us evaluate the argument. Remember that this dinosaur skeleton is earlier than T. rex, so we can't claim that the newly discovered skeleton inherited its traits from T. Rex. Regardless of whether this dinosaur was an ancestor of T. Rex or was unrelated, we would still have to explain why the characteristic T. Rex features developed for a dinosaur that was nowhere near the T. Rex's size and weight. So answering this question "yes" or "no" would still not give us useful information for evaluating the argument.
e
Did the recently ██████████ ████████ ████ ██ ███████ ██ █████ ██ █████ ████ ██ ███ ██████ ███
Irrelevant. We don't know how large the species T. Rex preyed on were: for all we know, perhaps it tended to prey on smaller species. So knowing whether or not the smaller dinosaur with T. Rex-like features preyed on the "same size" of species as the T. Rex doesn't actually tell us very much. It certainly doesn't help us determine why the T. Rex's features arose, and whether or not they developed to accommodate its size and weight.