Additional Flaw #58

[Nadia0702]

Hi PS,
This question tripped me up a bit, and it might be just because of a "tiny" detail of language. In Causal Reasoning on the LSAT, the cause ALWAYS causes the effect, there is no effect without the cause. So on this question the psychologist says that trauma must not cause phobias because it doesn't do so ALL the time. Well isn't that correct causal reasoning? If the cause (trauma) doesn't lead to the effect (phobia) ALL the time, and the effect (phobia) can exist without the cause (trauma), then why is the conclusion - that trauma "does not contribute to phobias" flawed reasoning? I think I know the answer but I don't like it Is it because "do not contribute" is not the same as "cause" ?

Second part of my question - can you please translate correct answer choice D into good ol' English?

Thank you!!!
Nadia

[Jacques Lamothe]

Hey Nadia,

I am happy to help, but I am having some trouble finding the question that you are asking about. What page of the Lesson 7 homework is #58 on?

Jacques

[Nadia0702]

Hi Jacques, it's a question on the supplemental "Additional Flaw" questions found on the student website.

Nadia

[Jacques Lamothe]

Alright, now I see it! Your suspicion about the phrase "do not contribute" is correct. That phrasing does make the argument slightly different from one that concludes "traumatizing events do not cause phobias." To give a general example, event A can contribute to the occurrence of event B even if B does not always happen after A happens. The important thing is that A increases the likelihood of B occurring. That's why the psychiatrist in the stimulus is wrong to infer the conclusion from the information that "not everyone who is traumatized by an event develops a phobia."

However, I think you are making a small mistake in your characterization of causal reasoning questions on the LSAT. It's true that when the author of a Logical Reasoning stimulus makes a causal claim, they are making an argument that the effect is always produced by the same cause (you would have picked this up from your initial introduction to causal reasoning in lesson 3). That does not mean that identifying a situation in which the effect occurs without the cause is sufficient to disprove the causal relationship.

As an example, If I observed that lots of people eat ice-cream on hot days, I might make the causal claim that hot days cause people to buy ice-cream. You could respond to my argument by telling me that you have seen people eat ice-cream on very cold days. That definitely weakens my causal claim, because it is now possible that there is some other cause that makes people eat ice-cream on hot and cold days. But it does not prove that my argument is wrong. You would be mistaken to say that, on the basis of observing people eating ice-cream on cold days alone, you know that hot days do not cause people to eat ice-cream. It's possible that the amazing taste of ice-cream causes people to eat it on cold days and that heat causes other people to eat ice-cream on hot days.

And that brings us back to the question that you asked about. The conclusion of the psychiatrist's argument is that "traumatizing events do not contribute to the occurrence of phobias." Rather than arguing that some causal relationship does exist, the psychiatrist is denying the existence of a causal relationship. But the psychiatrist does this by pointing out that the effect does not always follow the cause. Just like (in my long-winded example above) it would be wrong to say we can be certain that hot days do not cause ice-cream just because we observe people eating ice-cream when it is not hot out, the psychiatrist is wrong to say we can be certain traumatizing events do not contribute to phobias just because phobias sometimes appear without a preceding traumatizing event. So even if that conclusion switched out the phrase "do not contribute" for the phrase "do not cause," it would still be flawed.

I hope that helps with your first question! The important part for understanding the flaw with the question is distinguishing the phrase "do not contribute" from the phrase "do not cause," which is what I talk about in the first paragraph of this answer. The rest is a long-winded side note that I included to help you think about causal claims in Logical reasoning questions. I really hope I did not accidentally make things more confusing by adding it. Please let me know if you want me to clear anything up.

To answer your second question, Answer choice (D) roughly says: "assumes that something can only contribute to the occurrence of something else if those two things always occur together."

Jacques

[Nadia0702]

Hi Jacques,
Thanks so much for your response, it does help a lot. At the risk of over-thinking this, I'm going to state my understanding of what you said. Essentially, you cannot "disprove" a causal argument simply by stating that the effect is happening without the cause. What you do by stating that is simply weaken the argument and call into question its validity. So essentially the psychologist's flaw is that he saying to be absolutely true that traumatizing effects do not contribute to phobias when the evidence that he is citing may simply "weaken" the argument that trauma causes phobias were someone to make that argument - Yes? Maybe it's time to go to sleep

Thanks!
Nadia

[Jon Denning]

Hey Nadia,

Thanks for the questions. I'm going to just quickly jump in and give my thoughts.

Jacques is correct in noting (with a good example, I might add) that the idea of "hot days cause people to eat ice cream" is not necessarily proven wrong by observing "some people eat ice cream on cold days," if you take "wrong" to mean completely false. But on the LSAT, for an argument to be considered wrong, all you have to do is show that it is not 100% right--something that ice cream on cold days would certainly accomplish. I think a lot of test takers tend to view wrongness in absolute terms, where an argument that isn't right means that it is essentially impossible. However that's not the case! The burden of proof is on the author, so anything that shows the conclusion/argument may not be exactly as it's believed to be means that the argument itself is incorrect as given.

And that's a particularly important idea for causality! Causality is reasoning at its most fragile/vulnerable, because it is SO easy to introduce doubt about the 100% correctness (or constancy) of the relationship. Showing the effect without the cause is a great way to introduce that doubt (they don't always go together!) and thus makes the author's belief incorrect on the test.

Hope that helps!