LSAT 158 - Section 3 - Question 04

This is a Flaw/Descriptive Weakening question.

The argument opens with a general principle. Generally, it’s important that people practice what they preach but there are exceptions. The next sentence opens with “For instance…” which means we’re about to get premises. The argument is saying, “Let me show you instances of the exceptions, in case you don’t believe me.”

Okay, so what are the “instances”? Doctors don’t have to have healthy lifestyles in order to treat people. So that’s an instance. Also, logicians don’t have to be logical in their discussion of logic.

Had the argument simply been presented like that, then where we would question the reasoning would be on the two supposed instances “exceptions.” We could argue whether doctors are an exception to the rule or if they actually fit into the rule. We might argue that, actually, it's important for doctors to practice what they preach for whatever reason. This is what Answer Choice (B) tries to argue. And then we’d try to do the same for logicians. Do they fit the rule or fit the exception?

But the actual argument isn't just "For instance, doctors are an exception and logicians are an exception." The actual argument analogizes logicians to doctors. In so doing, the question of whether either fits the rule or the exception becomes entangled. They are no longer separate analyses.

The actual argument pegs whether logicians must practice what they preach to whether doctors must practice what they preach, as if answering the question for doctors reveals some information that answers the question for logicians. That is the crucial assumption at play.

• Assumption: With regard to whether it's important to practice what you preach, doctors and logicians are analogous.
• Premise: Doctors don’t need to have healthy lifestyles to treat people.
• Sub-conclusion: Logicians don’t have to be logical to discuss logic.

That assumption is fallacious because doctors and logicians are not analogous in that regard. This is what Correct Answer Choice (A) points out. If a doctor doesn’t practice what she preaches, then she can still effectively do her job of being a doctor: treat people. If a logician doesn’t practice what she preaches, then she can no longer do her job of being a logician: logically discuss logic. One can even question to what extent an illogical logician can even be considered a logician. Yet a doctor with an unhealthy lifestyle is no less a doctor. (A) points this out. It says that the argument is weak because it failed to take into account that logicians’ being illogical constitutes incompetence whereas physicians’ having unhealthy lifestyles doesn’t. This is where the two situations are relevantly dissimilar.

Answer Choice (B) says that the argument is weak because it fails to take into account that if a physician’s health deteriorates badly, the physician may not be able to treat patients effectively. This is descriptively accurate but it’s not where the argument is weak. We’ve already discussed how (B) fits into the argument above. (B) offers a reason for a doctor to “practice what she preaches” by pointing out what could happen on the far end of the spectrum. How effectively does this challenge a doctor being an “exception” to the rule? Not that effectively. The argument’s point stands for most cases. In general, a doctor’s having an unhealthy lifestyle does not prevent her from treating people, even though it’s true that if her health deteriorated badly, then she won't be able to treat people anymore. So (B) isn’t very effective in challenging the claim that doctors are an exception.

If we interpreted (B) to address the issue of the disanalogy, that would be even worse for (B). Let’s just assume that doctors aren’t exceptions, that they instead fit better into the rule. That they should also practice what they preach. If we grant this concession, (B) seems to be arguing that logicians also should not be exceptions to the rule either. The questionable aspect of the reasoning or why it feels wrong to us to say that logicians don’t have to be logical, according to (B), is that the argument fails to take into account that doctors actually do have to practice what they preach. See, says (B), doctors have to do it and so logicians should as well. Problem solved. Logicians do have to be logical, after all.

No. That entirely misses the point! The reason why the analogy failed in the first place is because doctors and logicians are essentially disanalogous when it comes to “practice what you preach.” Whether doctors have to or not reveals no information about whether logicians have to or not, because they’re dissimilar in that regard. They’re disanalogous. (A) pointed that out already. (B)’s reasoning still assumes that doctors and logicians are actually analogous; we just got the direction wrong, that doctors actually aren’t exceptions.

Answer Choice (C) says that the argument is weak because it fails to take into account that doctors who are incompetent to practice medicine can cause more harm than can logicians who discuss logic illogically. Okay, (C) tries to point out a difference between doctors and logicians. The problem is that (C) can’t point to just any difference. The difference has to matter. That’s what’s meant by “relevant” dissimilarity (if you’re trying to disanalogize) or “relevant” similarity (if you’re trying to analogize). What counts as “relevant” changes depending on what specifically the argument is talking about. Here, we are talking about why it’s important for logicians to practice what they preach yet not as important for doctors to practice what they preach. What’s “relevant” isn’t the disparate impact that doctors and logicians have on other people, because that doesn’t expose the disanalogy. What exposes the disanalogy is, again, what was already discussed in (A).

Perhaps a different argument will illustrate the point: doctors are required to attend four years of medical school and then complete four years of residency before they are allowed to practice their trade. Therefore, logicians should also be subject to similar educational requirements. This argument by analogy is vulnerable because of what (C) says. The reason why doctors are required to go through eight years of training is because they have the potential to cause great harm. This is a point of relevant dissimilarity between doctors and logicians. This dissimilarity is why the argument’s reasoning by analogy fails.

Answer Choice (D) says that the argument is weak because it fails to take into account that it’s more difficult to become logical than it is to modify an unhealthy lifestyle. Similar to (C), (D) points out a difference but not a relevant difference. The fact that it’s harder to become logical than it is to adopt a healthy lifestyle isn’t why the argument’s reasoning by analogy fails. Even if the two endeavors were equally difficult, the argument’s reasoning by analogy would still fail for the reasons stated in (A).

Answer Choice (E) says that the argument is weak because it fails to take into account that it’s not necessary for logicians to be logical in order to competently discuss logic, though it is highly desirable. No, it is both highly desirable and necessary for logicians to be logical in order to competently discuss logic.