Psychologist: Identical twins are virtually the same genetically. Moreover, according to some studies, identical twin...

Leila on August 14, 2013

Psychologist

I need help with diagraming and why D is the answer and not the others ... Thank u!

4 Replies

Leila on August 14, 2013

Weaken : point out the flaw ...

1) flaw of inclinations being related to genetics ... I skipped because of the first sentence

2) flaw of thinking not subject to environment just because we don't have evidence for it ... Works because it is opposite the conclusion ... So I am sticking w this when going through answer choices ...

In passage I am thinking these people lived in different environments and yet has similar inclinations ... Contra positive ... If they don't have similar inclinations then they live in a similar environment

D is opposite if that premise because it shows similar inclinations in a similar environment.

Furthermore, I diagramed the conclusions like this:

I -> G & ~E
E or ~G -> ~I

D works because it weakens the above conclusion by showing when the environmental influence was there, they has similar inclinations (that's why they forcefully changed then to differentiate themselves)

Mehran on August 15, 2013

There is nothing to diagram in this stimulus as we do not encounter any sufficient and necessary conditions (i.e. no conditional statements).

The Psychologist's conclusion is "many of our inclinations must be genetic in origin and not subject to environmental influences." He supports this conclusion by referencing studies where identical twins who were separated at birth and brought up in vastly different environments still showed similar ethical beliefs, dressed the same way and had similar careers.

This is a cause and effect argument. The observed effect that the Psychologist is trying to explain is why identical twins who were separated at birth and raised apart still showed similar ethical beliefs, dressed the same way and had similar careers. The Psychologist's proposed cause for this observed effect is genetics.

We are asked to weaken this argument so let's take a look at the answer choices.

(A) is irrelevant. So what if some people, including twins, undergo radical changes in their lifestyle at some point in their lives? This has no impact on the Psychologist's conclusion that "many of our inclinations must be genetic."

(B) does not weaken because the conclusion is "many of our inclinations" as opposed to all our inclinations (i.e. the author concedes that there might be differences).

(C) is irrelevant. This is not a discussion about what scientists can or cannot do at this time.

(D) weakens this argument because it is a counterexample to the studies cited in the Psychologist's argument. If these identical twins (i.e. virtually identical genetically) who grow up together have different beliefs, tastes and careers, it would weaken the argument's conclusion that it is not environmental influences but rather genetic by showing the cause (i.e. virtually identical genetically) without the effect of similar inclinations.

(E) seems to strengthen because when we don't see identical twins (i.e. not virtually identical genetically), we don't see similar beliefs, tastes and careers (i.e. no cause, no effect).

Hope this helps! Please let us know if you have any other questions.

Gilbert on September 21, 2014

I understood all this and was leaning towards D, but the statement about them doing so in order to differentiate themselves, makes it seem as though they still have the same inclinations but they just want to distinguish themselves so they act differently.

Melody on September 30, 2014

Which answer choice did you go with if you didn't choose (D)? I understand your hesitation about (D), but the rest of the answer choices are quite obviously incorrect. Answer choice (D) gives us an example where two people with virtually identical genetics grow up to have different beliefs, tastes and careers.

Remember, this is a cause and effect argument. Thus, to weaken it, we must show the cause without the effect. The cause was presumed to be similar genetics. Answer choice (D) shows us the exact same genetics and yet different beliefs, tastes and careers.

Thus, even though it's true that the statement mentioning "differentiating" could mean that they might still have the same inclinations, but are merely making themselves choose varying beliefs and careers to differentiate themselves, it is still the only answer choice that works to weaken the argument. You can refer to the explanations Mehran gave above as to why the rest of the answer choices are not correct.

Hope that clears things up! Please let us know if you have any other questions.