Logical reasoning PrepTest 121 · Section 4 · Question 21

Correct. Argument or Facts:
Argument

Valid or Flawed:
Flawed

Question Type:
Strengthen with Sufficient Premise

Stimulus Summary:
not Accept unpleasant realities and speak about them honestly → not Sincerity
not Community members trust each other → not Community succeeds
Therefore - Community succeeds → Accept unpleasant realities and speak about them honestly

Answer Anticipation:
Strengthen with Sufficient Premise questions frequently deal with conditional logic. When there are multiple conditional statements that have overlapping terms, we should start with the conclusion and see how everything works together, and where the gap in the logic is.

In this case, it's even more important to start with the conclusion because the first statement is very difficult to diagram in a way that lines up with the rest of the argument if you're not working with the conclusion first.

So we need to build a bridge between Community succeeds and Accept unpleasant realities and speak about them honestly—the conditional in the conclusion. It's a lot clearer to see that the second sentence includes the idea of the community succeeding, so let's start there.

In that conditional, there's a sufficient condition for the community not succeeding, so we need to take the contrapositive to get it to line up with the conclusion:
Community succeeds → Community members trust each other

That builds from the sufficient condition of the conclusion, but there's no other mention of community members trusting each other, so that's the end of this side of the chain. The correct answer will connect this idea (as a sufficient condition) to another concept.

The necessary condition of the conclusion is accepting unpleasant realities and speaking honestly. Looking at the opening line of the stimulus, we see there a discussion of ignoring unpleasant realities and telling small lies—which is the negation of that term in the conclusion. According to that sentence, if a community acts in such a way, then there can't be sincerity. And to get this to line up with the conclusion, we need to take the contrapositive:
Sincerity → Accept unpleasant realities and speak about them honestly

There's no other mention of sincerity in the stimulus, so this is the entire chain that builds to the necessary condition of the conclusion. Now, to allow the conclusion to follow logically, we just need to connect the chains (the contrapositive would work, as well):
Community members trust each other → Sincerity
not Sincerity → not Community members trust each other

Answer Explanation:
Community members trust each other → Sincerity. This answer is exactly our anticipation, bridging the gap between the two premises to establish the conclusion as true.

Key Takeaway:
More complicated conditional arguments will have difficult-to-diagram statements and terms that are equivalent even if phrased a bit differently. Starting with the conclusion can give you structure through which to approach the other statements, making diagramming them in a way that's helpful much easier.

Incorrect. This answer makes comparative statements ("more likely"; "more sincere"), but the stimulus is about absolute ones ("sincerity", "to succeed"). These comparative statements aren't enough to justify the stronger conclusion—something could be more likely to happen but still fail.

Incorrect. This answer is contradicted by the stimulus—traditional norms lead to insincerity, which is sufficient to guarantee there's no trust between community members and thus no community success.

Incorrect. not Face unpleasant realities → not Sincere. Even ignoring the shift in the sufficient condition here from the term in the stimulus, this answer has not Sincere as a necessary condition, whereas we needed that as a sufficient condition, so this answer is a reversal.

Incorrect. This answer is weaker than the conclusion ("often"), and so it can't justify it.