#21 - Wirth: All efforts to identify a gene responsible for

[Dave Killoran]

Complete Question Explanation

Point at Issue. The correct answer choice is (D)

Wirth's argument is that since all efforts to identify a gene responsible for manic-depression have failed, therefore any claim that people are genetically predisposed to manic-depression is false. This is a very extreme claim and the language in the conclusion is overly broad and absolute.

Chang agrees that "All efforts to identify a gene responsible for predisposing people to manic-depression have failed. In fact, nearly all researchers now agree that there is no 'manic-depression gene' " but then specifically disagrees with the "claim that some people are genetically predisposed to manic-depression."

It's an exchange that forces you to understand premises and conclusions, and if you aren't clear on the meaning of Chang's "I agree with your evidence butt not your conclusion" statement, you will struggle with this question.


Answer choice (A). Wirth talks about "a gene" but says nothing whatsoever about a "set of several genes" or the research efforts around those, so we don't know Wirth's opinion on the full statement in (A), meaning that alone is enough to kill off (A).

Chang seems more likely to disagree than agree with (A), not on the basis of the single gene but on the actions of multiple genes. Thankfully, we don't have to worry about Chang's view's here since Wirth's lack of opinion alone eliminates (A).

Answer choice (B) uses very strong language, and the presence of "ever" extends this answer infinitely into the future. Wirth hasn't talked about the future, and Chang hasn't discussed single genes aside from agreeing that up until this point all efforts to find a single gene responsible have failed.

Answer choice (C). Both speakers agree with this statement.

Answer choice (D). This is the correct answer choice. Wirth agrees with this statement and Chang disagrees.

Answer choice (E). There is only a reference to current efforts failing; there is no discussion about how thorough those efforts were.

[alexwardschmidt]

I am having a hard time understanding this one because I think that Chang would disagree with A. The very thing that he said (a set of several genes is involved and that complex interactions among these genes produce a predisposition to manic-depression) is a perfect description of predisposition: these genes, interacting with other complex factors, cause some people to get manic-depression.

Additionally, I do not understand how researchers could identify that there is a set of genes without having some idea of what that set of genes is. To me, the language that the researchers have identified 'a set' of genes indicates that they have some information about the identity of these genes, or am I not approaching the language correctly?

Thanks for your help.

[Dave Killoran]

Hey Alex,

Good question! I just wrote a new official explanation at the top of the thread because I didn't love the answer that was there (I've killed that), mainly because I don't see Wirth as the one agreeing with (A)! Wirth talks about "a gene" but says nothing whatsoever about a "set of several genes" or the research efforts around those, so I don't think we know Wirth's opinion on the full statement in (A), meaning that alone is enough to kill off (A).

I'm on your side that Chang would be more likely to disagree than agree with (A), not on the basis of the single gene but on the multiple gene front as you say. Thankfully, we don't have to worry about Chang's view's here since Wirth's statement alone eliminates (A).

Thanks!