Errors in Reasoning

@EvanW, this is an "error in reasoning" question, so you're looking for the answer that weakens the given argument logically. This often occurs by re-interpreting a piece of information or undermining a key premise. With this question, the conclusion is that hospital patients who are more prone to laugh were helped more by laughing a little bit than those who are less prone to laugh were helped by laughing a lot. So let's look at how they got there. First, hospital patients who were shown comic videos showed a tendency to recover more quickly, which is used to suggest that laughter helps with recovery. Second, hospital patients who were prone to laugh showed a more significant benefit to laughing. The author uses this to conclude that a little laughing from a happy person is more effective than a lot of laughing from a less happy person. As you can see, there's a logical leap between the second premise and the conclusion, so we're looking for the answer that points that out. (A) does this by pointing out that if laughing helps with recovery, it is possible that the people who were prone to laugh recovered better because they laughed more when shown the comic videos. This provides an alternate interpretation of a premise, which undermines the conclusion. Does that help?

Yes that clears things up, thank you!

Hello, In the question it says that the patients who had a tendency to laugh more to begin with laughed less than the other patients. "helped more in their recovery from illness even when they laugh a little than other patients are helped when they laugh a greater amount" then the answer goes on to say that the patients who have the tendency to laugh more did in fact laugh more at the video. does this not contradict the part of the question i quoted above?

@jack515, Great question. The portion of the stimulus that you quoted is part of the argument's conclusion. This is a flawed conclusion, as the only premise we're given in the argument is that having a tendency to laugh is correlated with gaining immune system strength. The problem with the argument's conclusion is that it is taking a correlation between the tendency to laugh and immune system strength and falsely inferring that having a high tendency to laugh causes larger gains in immune system strength. Additionally, another flaw of the conclusion is that it assumes that the causal impact of having a tendency to laugh is stronger than the causal impact of the other variable (which is how much a given patient laughed). We simply do not know whether that is true or not, as we don't have enough information. In fact, given the context of the argument, which states that laughter causes better recovery, we have reason to believe that the amount of laughter, and not the tendency to laugh, was the primary component of aiding recovery. Answer choice A is correct because it weakens the argument's causal conclusion by introducing an alternative cause that is entirely possible. It's totally reasonable that patients whose tendency to laugh was greater to begin with laughed more at the comic videos than did the other patients. If A is true, then the correlative effect in the premise of the tendency to laugh being correlated with gaining immune system strength is explained away by the causal relationship provided in the context of the argument (laughter causing better recovery). If this is true, then this casts serious doubt on the author's conclusion, and this is why the argument is vulnerable to criticism—it's overlooking this fact.

From the explanations above, I can see why A is correct, but wouldn't B also be a flaw in this case?

Hi @Minerva, B is not a flaw because the passage is discussing gains in immune system strength. If the passage claimed that patients with a greater tendency to laugh to begin with had the strongest immune systems at the end of the study, this would be a flaw. But, because it discusses gains in immune system strength, this would be relative to how strong each patient's individual immune system was at the beginning of the study. Hope this helps! Please let us know if you have any further questions.

Why is D incorrect?

Hi @amf, As Ravi mentioned above, the flaw in reasoning is its assumption that having a greater tendency to laugh has a stronger impact on a patient's recovery than the amount a given patient laughed. There is not enough evidence provided in this passage to support this assumption. That is why answer choice (A) is correct. Answer choice (D) is incorrect for two reasons: (1) The passage states that patients who received greater health benefits had a greater tendency to laugh "to begin with," i.e. prior to becoming ill. Therefore, it does not follow that the health benefits a patient received influenced their tendency to laugh as the passage suggests that this tendency existed as an independent trait of each given patient. (2) Answer choice (D) suggests a flaw in the passage's causal reasoning whereas the real flaw in the passage is the lack of evidence provided regarding the amount that patients laughed at the comic videos. Hope this is helpful! Please let us know if you have any further questions.