Logical reasoning PrepTest 158 · Section 3 · Question 4

Argument or Facts:
Argument

Valid or Flawed:
Flawed

Question Type:
Errors in Reasoning

Stimulus Summary:
The columnist's main conclusion is that there are exceptions to the old saw that it's important to practice what you preach. The columnist works from the premise that physicians don't need to maintain healthy lifestyles to treat patients, and then proceeds to conclude that there's another exception: logicians don't have to be logical in their discussion of logic, either.

Strategy Overview:

1. Argument or facts? Always argument, so identify premises and conclusions of argument
2. Anticipate why the premises are not enough to prove that the conclusion is true
   1. Checking to see if a common logical fallacy is committed is very helpful
3. Use anticipations to select the answer choice that:
   1. Accurately describes the reason why the premises are not enough to prove that the conclusion is true

Answer Anticipation:
This compact argument has an interesting structure worth unpacking. Note how the author claims "it's no more necessary" for logicians to be logical than it is for physicians to maintain a healthy lifestyle. So, the author is making a claim about logicians and supporting that claim with a comparison to physicians. Therefore, the author uses the physicians as a premise to draw a subsidiary conclusion about logicians. In turn, the subsidiary conclusion supports the main conclusion. Because this argument has a main conclusion and a subsidiary conclusion, we can look for a flaw in the inference the author makes between the premise and the subsidiary conclusion, or for a flaw in the inference between the subsidiary conclusion and the main conclusion.

First, let's address the leap from the premises to the subsidiary conclusion. This leap is based on an analogy between logicians and physicians. If physicians don't need to follow their own advice to their jobs, the author argues, then logicians don't need to follow their own advice to do their jobs either. Whenever an argument rests on an analogy drawn between two things, an experienced test taker will begin to wonder if those two things are not actually that similar. Maybe there are key differences between logicians being logical and physicians maintaining a healthy lifestyle, and those differences suggest that it's actually more necessary for a logician to be logical. An answer choice that pointed out one such difference would identify a flaw in this argument.

Next, we can address the leap from the subsidiary to the main conclusion. The main conclusion asserts that there are cases in which you don't need to practice what you preach. The subsidiary conclusion then lists one example: logicians don't need to be logical to continue preaching the gospel of logic. When an author uses an example to illustrate a point, a well-versed LSATer will ask whether that example actually illustrates the point the author believes it does. So is it the case that logicians, as this author claims, do not need to practice what they preach? Can they be illogical and still maintain the illustrative title of "logician"? Maybe not. Being logical seems like the whole point of being a logician. Maybe being illogical would disqualify one from being a logician. An answer choice that clarifies why a logician might need to be logical would also identify a flaw in this argument.

Answer Choice Explanation:
This answer choice points out a relevant difference between logicians and physicians. A physician having an unhealthy lifestyle wouldn't affect that physician's competency to treat patients. But a logician failing to be logical would make that logician incompetent to discuss logic. That would mean that the logician, unlike the physician, is an example of a person who does need to practice what they preach. The author fails to consider that important difference between physicians and logicians, which makes the author's argument-by-analogy very questionable.

Key Takeaway:
This is a compact argument with a surprising amount of nuance, especially for the fourth question in a section. In fact, the correct answer could have been much more difficult to spot, if the test writers were feeling slightly more evil when writing the answer choices. And answer choice, in particular, was a very tricky answer choice to eliminate and will likely throw off many test-takers.

If you’re typically very good at answering the early questions in an LR section, but this one was surprisingly difficult for you, don’t let that shake your confidence! Paradoxically, the difficulty you experienced could be a sign that you’re seeing this question in all of its complexity, and that you possess a strong understanding of arguments.

In attempting to undermine the author's claim that physicians do not need to maintain a healthy lifestyle, this answer choice attacks a premise to the author's argument. Remember, correct answers to Errors in Reasoning questions will not do this. Identifying a flaw in an argument's reasoning is all about showing why the premises, if true, are not enough to support the argument's conclusion. It's not about showing why the premises may not be true.

Even if we ignore that issue, this answer choice doesn't really show why a physician might not need to maintain a healthy lifestyle. Maintaining a healthy lifestyle and staying in good health aren't quite the same thing. A physician failing to maintain a healthy lifestyle does not necessarily mean that the physician's health will "deteriorate badly." (Likewise, physicians’ health can deteriorate even if they maintain healthy lifestyles.) Because this author is discussing physicians maintaining "healthy lifestyles" and not physicians "being healthy," this answer choice doesn't quite point out why physicians might need to practice what they preach.

This answer choice wants us to believe that this is a relevant difference between physicians and logicians. But, by discussing a physician's incompetence, the answer choice brings up an issue that's irrelevant to the argument. This author's point wasn't about physicians being incompetent to practice medicine. It was about physicians who do not maintain a healthy lifestyle. Those are entirely different concepts, so this answer choice does not point out a difference between physicians and logicians that's germane to the argument.

The author's point was that logicians don't need to be logical to do their job. Since the author doesn't think that trait is necessary, the author isn't concerned with how easy it is to acquire that trait. To identify a flaw in this argument, we should look for an answer choice that shows why logicians need to be logical, not an answer choice that discusses how difficult it may be to become logical.

To identify a flaw in this argument, we can look for an answer choice that shows why logicians need to be logical. The problem with this answer choice is that it concedes that the author's whole point is valid. It says that logicians don't have to be logical to do their job. Rather than point out a flaw in the argument, this answer choice affirms the argument's conclusion.