Logical reasoning PrepTest 142 · Section 1 · Question 20

Incorrect. This answer is the negation of one of the conditionals, but that conditional was correctly chaining together to reach the conclusion, so this answer adds nothing to the argument.

Incorrect. While this answer might explain how an increase in the number of visitors would lead to tax revenues increasing, that connection was already made, so there's no need to explain it or add a step in there.

Incorrect. This answer is the negation (or reversal, depending on how you diagram "unless") of the conclusion, so it doesn't do anything to justify it.

Incorrect. The premises guarantee that the total number of visitors will increase, so it doesn't matter if they're all new or if some of the old ones return.

Correct. Argument or Facts:
Argument

Valid or Flawed:
Flawed

Question Type:
Strengthen with Sufficient Premise

Stimulus Summary:
Build convention center → NPOs will hold conventions there
Several large conventions → Total # of visitors increase
Total # of visitors increase → Tax revenue increase
Therefore: Building convention center → Tax revenue increase

Answer Anticipation:
This argument has a ton of conditional statements that seem to keep chaining together, and the argument seems to validly connect all of them in reaching the conditional conclusion! If you didn't fall for this and saw the gap on your first read-through, great work. If you did think this was a valid argument, then some advice. When you think that a conditional argument is valid and you know it's not (you can't strengthen a valid argument, after all), there are two things to check:

(1) Did I flip any of the conditional arguments? This is less common in Strengthen with Sufficient Premise questions since fixing it would require you to find an answer that replaces the premise with its reversal, which would be weird. This is much more likely in an Errors in Reasoning question.

(2) Did I treat two terms as being equivalent when they're not? This is common in Strengthen with Sufficient Premise questions, where the LSAT writers are doing everything in their power to get you to mess up and think two distinct terms are equivalent!

You should head back to the stimulus and see if there are any terms shifts you didn't note. Here, one likely place where people have been tripped up is in the jump from the first conditional to the second. It can be easy to think that the NPO conventions would be "several large convention[s]". However, it never establishes that these conventions will be large.

Going through the rest of the terms, there are no gaps, so the correct answer will plug this one—If an NGO holds a convention, it'll be large.

Answer Explanation:This answer bridges the conditional gap between the two premises that have a similar but not equivalent term. By bridging that gap, the conditional premises can all be chained together, thus guaranteeing the validity of the conclusion.

Key Takeaway:
If you're dealing with a conditional argument that you know is flawed but you think is valid, check two things (which is first depends on the question type):

(1) Did you mess up the direction of one of the conditionals? This is more common in Errors in Reasoning and Flawed Parallel Reasoning.

(2) Did you treat two distinct terms as being the same? This is more common in Strengthen (all types) and Weaken questions.