Logical reasoning PrepTest 121 · Section 4 · Question 16

Incorrect. Since this answer concludes a tax is effective, it's applying principle #1. The sufficient conditions for that principle are that it raises revenue (check), and that it burdens all and only those targeted. This answer, however, states that the cigarette tax burdens most, not all, of those targeted by it (and it doesn't establish it doesn't burden others), so this answer is incorrect because it fails to meet the sufficient condition of that principle.

Incorrect. Since this answer concludes a tax is ineffective, it's applying principle #2. The sufficient conditions for that principle are that it doesn't raise revenue and costs a significant amount of money to enforce. And while this tax does cost a significant amount of money to enforce, it also raises a modest amount of money, so it fails to meet the first sufficient condition. It is therefore incorrect.

Correct. Argument or Facts:
Facts

Question Type:
Must Be True (Principle)

Stimulus Summary:
(1) Raises revenue AND Burdens all/only those targeted → Tax effective
(2) not Raises revenue AND Costs significant money to enforce → Tax ineffective

Answer Anticipation:
As with most Must Be True (Principle) questions, we're presented with two conditional statements that reach opposing judgments (effective/ineffective). We should diagram them, make sure that the opposing judgments are in the necessary conditions (taking the contrapositive when needed, which it isn't here), and then find an answer that correctly applies one of them.

An important note on the first conditional—that second sufficient condition could probably be itself turned into a conditional since it includes the phrase "all and only those." In fact, that's a biconditional indicator phrase. However, that'd make the conditional exceptionally complex, and we can probably figure out if an answer choice matches up with that condition without digging into the conditional, so let's not mess with it unless we absolutely have to.

An important note on the second conditional—we wrote out the necessary condition of the second statement as "Tax ineffective" instead of "not Tax effective". While the two might mean the same thing, making sure that our terms overlap when possible is only important when we're trying to chain the conditionals together. Since that's not the goal in this question type, we should get the necessary condition/judgment to reflect what the stimulus says, as that's likely how the answers will be phrased.

With that established, let's head to the answer choices. We can support a conclusion of a tax being either effective or ineffective, so our job will be to use the argument's conclusion to note which of the two principles applies and then see if it gets the details right.

Answer Explanation:
Since this answer concludes a tax is ineffective, it's applying principle #2. The sufficient conditions for that principle are that it doesn't raise revenue and costs a significant amount of money to enforce. This answer establishes that the gas tax costs a significant amount of money to enforce and conditions its conclusion on it not raising revenue, so this answer is correct.

Key Takeaway:
Note that the correct answer here established one of the sufficient conditions for the principle as a condition on the conclusion. That's fine! Conclusions with a condition/qualification attached are saying, "This conclusion only holds true in these cases," which means that it can limit itself to cases where a sufficient condition of a principle/conditional is met.

Incorrect. Since this answer concludes a tax is effective, it's applying principle #1. The sufficient conditions for that principle are that it raises revenue, and that it burdens all and only those targeted. While this answer establishes the latter sufficient condition, it doesn't discuss whether the tax raises revenue. It is therefore incorrect.

Incorrect. Since this answer concludes a tax is ineffective, it's applying principle #2. The sufficient conditions for that principle are that it doesn't raise revenue and costs a significant amount of money to enforce. And while the steel tax doesn't raise revenue, it also doesn't cost a significant amount of money to enforce. Since it fails to meet one of the sufficient conditions, we can't conclude that it's ineffective.