Logical reasoning PrepTest 157 · Section 3 · Question 23

This is tempting! After all, superstring theory's failure to explain why the force of gravity is not stronger or weaker than it is is a "problem" for this author. So, wouldn't the theory be more successful if superstring theorists attempted to explain why the force isn't stronger or weaker than it is?

Well, who's to say they haven't already attempted to explain that? The author just says the theory has had "no success" in explaining why gravity isn't stronger or weaker than it is. It's possible that the superstring theorists have tried and failed to explain this. So, theorists could have attempted to explain this, yet it's still true that superstring theory isn't successful.

Well, it seems plausible that there must be other theories that are more successful than superstring theory. But ... the passage didn't tell us about any of those. The passage never discussed or even alluded to other theories that are more established than superstring theory. So, we don't have any evidence to support the claim that this answer choice makes. Remember our mantra for Connecting Facts questions — when connecting facts, stick to the facts!

This is basically the same answer choice as (B), except it tries to bait us with the kind of weak language we typically like on Must Be True questions ("some") and repeated phrases from the passage. However, the passage didn't tell us about any other physical theories, so we don't have any evidence to conclude that another theory has better explained why gravity isn't stronger or weaker than it is. Remember our mantra for Connecting Facts questions — when connecting facts, stick to the facts!

This is a bit too bold! The author says that superstring theory has a few "problems" — not that superstring theory "cannot be true." While the author would call superstring theory problematic, unconvincing, and deficient, we don't know if the author would say that "cannot be true." Perhaps the author believes that superstring theory might be true, even if we can't feasibly test it. Remember, unconvincing theories and arguments can still be true!

This matches the inference we anticipated ("a theory purports to explain something like gravity, it should be able to explain why that force is as strong as it is"), so we confidently select it. After all, this passage's author must believe this claim is true. Suppose the author didn't believe this claim. Suppose the author thought that a theory that purports to explain the nature of a force (like gravity) isn't deficient, even if it can't account for the strength of that force. In that case, it wouldn't be a "problem" that superstring theory cannot account for why the force of gravity is not stronger or weaker than it is! So, we can confidently conclude that the author must believe that (E) is true.