Logical reasoning PrepTest 157 · Section 2 · Question 22

Diagramming this answer choice is a little complicated. But once we do, we'll see that it doesn't match our anticipation. To diagram this, we'll need to use the "No," a "then-denying" keyword. We can put either condition on either side of the arrow, so long as we add a "NOT" to the "then" side. That would give us this "if-then" statement and flipside:

Read stories → NOT fail to develop a lifelong interest in literature / Fail to develop a lifelong interest in literature → NOT read stories

If we use a "positive mindset" on the "NOT fail" double negative, we can translate that to simply "develop a lifelong interest in literature":

Read stories → Develop a lifelong interest in literature / NOT Develop a lifelong interest in literature → NOT read stories

As we can see, this doesn't resemble the "NOT read stories → NOT develop a lifelong interest in literature." Rather than connect the premise to the new idea in the conclusion, it says that if we don't have the premise, then we won't have the new idea in the conclusion. In other words, the correct answer to a Strengthen with a Sufficient Premise question should resemble "Premise → Conclusion." It shouldn't resemble "NOT Premise → NOT Conclusion." For this reason, (A) is incorrect.

This answer choice matches our anticipation! However, diagramming it is definitely challenging. We'll need to notice that the "only" is a "then" keyword. That will give us this "if-then" statement and flipside:

Develop a lifelong interest in literature → Read stories / NOT read stories → NOT develop a lifelong interest in literature

The flipside matches our anticipation, so we can confidently select (B) and move directly to the following question.

After all, if we add this premise to the argument, it becomes valid. Suppose that (B) is true — suppose that we know that if you don't spend your free time reading, then you won't develop a lifelong interest in literature. In that case, most children who spend their time watching TV rather than reading will not develop a lifelong interest in literature. So, this answer choice makes the argument valid. We can select it and advance to the following question.

We can eliminate this answer choice immediately because it lacks the new term in the conclusion. It doesn't discuss whether any kids "develop a lifelong interest in literature." Therefore, this can't make the conclusion valid. You can't have a valid conclusion with a term that doesn't appear in any of the premises, so adding this premise won't make the conclusion follow logically.

This doesn't match our anticipation. It doesn't connect the author's premise to their conclusion, whether we thought of that connection as a translated "if-then" statement ("If you do not read stories as a child, then you will not develop a lifelong interest in literature") or as a diagram ("NOT read stories → NOT develop a lifelong interest in literature"). Instead, it just establishes that people who watch a "great deal of television" will usually not develop a lifelong interest in literature. However, the author's premises don't say that most children watch a great deal of television. The premises just say that televisions are common and that few children "spend their free time reading stories." These children may spend their free time watching television instead of stories, but that doesn't mean they're necessarily watching "a great deal of television." In other words, since the author doesn't include a premise that establishes that most children watch a great deal of television, this answer choice does not connect the author's premise to their conclusion.

Like (C), we can immediately cross this answer choice off once we see that it lacks the new term in the conclusion. It doesn't discuss whether kids "develop a lifelong interest in literature." Therefore, this can't make the conclusion valid. A conclusion that features an idea that isn't discussed in any of the premises will never be valid, so adding this premise won't make the conclusion follow logically.