#18 - Doctor: Angiotensinogen is a protein in human blood.

[Jeff Wren]

Hi LeBronSAT,

Before diving into the answers and how the words "phenomenon" and "phenomena" are used, let's just summarize the argument itself and prephrase the flaw.

I've reordered the premises for clarity.

Premise 1: Disease X usually causes higher angiotensinogen levels.
Premise 2: Angiotensinogen levels are (positively) correlated with blood pressure.
Conclusion: Disease X is a cause of high blood pressure.

This is a causal argument and contains one of the several possible causal flaws. Specifically, the argument assumes that the higher angiotensinogen levels are causing higher blood pressure (and then trying to make a causal chain from Disease X to higher angiotensinogen levels to higher blood pressure) when all that is established is that angiotensinogen levels are (positively) correlated with blood pressure. A prephrase for this flaw would be "the argument assumes a causal relationship on the basis of only a correlation." This prephrase should help in identifying Answer C.

For the purposes of the LSAT, the definition of "phenomenon" is basically "a fact or situation that is observed to exist or happen." To keep it simple, you can think of a phenomenon as a thing/fact that happens or happened. It's not referring to the correlation itself.

However, to see how the word is used in each Answer choice, you need to read each answer choice and understand how the word is being used in the context of the answer.

What makes these answers so tricky is that there are 3 different "phenomena" addressed in the stimulus and the wrong answers confuse/mix the terms or their relationships.

In Answer C, the correct answer, "the phenomena being correlated" refers to 1. an increase in a person's angiotensinogen and 2. an increase in a person's blood pressure. The argument improperly assumes that, because these two phenomena are correlated, that one (an increase in a person's angiotensinogen) causes the other (an increase in a person's blood pressure). This is the assumption (i.e. unstated premise) being made that is necessary for the conclusion that Disease X is a cause of high blood pressure.

Answer D describes "one phenomenon causing a second with the second causing the first." It is not clear from this answer which phenomenon this answer refers to, but either way it would be incorrect because nowhere in the argument does the argument mistakenly reverse the cause and effect of any of the phenomena.

Answer E states that the argument assumes (i.e. takes for granted) that if one phenomenon (presumably Disease X) causing a second phenomenon (presumably higher angiotensinogen levels) and this second phenomenon causing a third phenomenon (presumably higher blood pressure), then the first phenomenon cannot be the immediate cause of the third. This is not what happens in the argument. This would be describing an argument where three things were established to be linked in a causal chain and then the conclusion is that the first cause cannot directly cause the third. As is mentioned above, the real flaw is that a causal chain between the three phenomena has not been established by the argument. Instead the argument improperly assumes that the causal chain has been established by confusing the correlation between two phenonema for a causal relationship.

[Administrator]

(disregard the first part of my post. Now I am seeing the replies. I just never received a notification.) Sorry.

Hi LeBronSAT,

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Julie Lipscomb
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[kristinajohnson@berkeley.edu]

Doctor: Angiotensinogen is a protein in human blood. Typically, the higher a person’s angiotensinogen levels are, the higher that person’s blood pressure is. Disease X usually causes an increase in angiotensinogen levels. Therefore, disease X must be a cause of high blood pressure.

Does this reasoning look okay?

(typically) higher angiotensinogen -> higher blood pressure

(usually) disease X -> higher angiotensinogen

The “usually” here belongs on the disease X side right? Not the higher angiotensinogen side?

disease X -> high blood pressure

(A) It confuses a necessary condition for a sufficient condition.

No

(B) It overlooks the possibility that even if a condition causally contributes to a given effect, other factors may fully counteract that effect in the presence of that condition.

I’m unsure if this is talking about disease X -> high blood pressure or disease X -> higher angiotensinogen? In any case is this wrong because of “other factors may fully counteract that effect in the presence of that condition” is not in the stimulus, right? Also, what relationship is it talking about?

So, “It overlooks the possibility that even if a condition [(usually) disease X] causally contributes to a given effect [higher angiotensinogen], other factors [not mentioned in the stimulus, right?] may fully counteract that effect [higher angiotensinogen] in the presence of that condition[(usually) disease X]. Tricky.

(C) It illicitly infers, solely on the basis of two phenomena being correlated, that one causally contributes to the other.

This looks good:

It illicitly infers [disease X -> high blood pressure], solely on the basis of two phenomena being correlated[(typically) higher angiotensinogen -> higher blood pressure AND (usually) disease X -> higher angiotensinogen](Are these the two phenomena?), that one[(usually) disease X -> higher angiotensinogen] causally contributes to the other[(typically) higher angiotensinogen -> higher blood pressure].

Is this the correct placement of the causes and effects the answer choice is referring to?

(D) It confuses one phenomenon’s causing a second with the second phenomenon’s causing the first.

No, the stimulus is saying one phenomenon is causing a second phenomenon, the second phenomenon is causing the third phenomenon, so the first phenomenon is causing the third phenomenon, is that right?

(E) It takes for granted that if one phenomenon often causes a second phenomenon and that second phenomenon often causes a third phenomenon, then the first phenomenon cannot ever be the immediate cause of the third.

No, that’s the opposite of what the stimulus is saying.

Thank you.