Q13 - It is a mistake to think

[tamwaiman]

I wonder why (D) is incorrect, both (B) & (D) include the conclusion that what ecologists once think is a mistake and have the same description: be perfectly adapted to their environment is impossible.

Thank you.

[manoridesilva]

I think D is wrong (i) because it says more than the main conclusion and (ii) it omits information from the main conclusion. (I stand to be corrected.)

As I read it, the main conclusion is the first sentence "It is a mistake....adapted to their environments." Therefore, the answer needed to include reference to it not being possible to ever adapt perfectly to environments AND natural selection. This already eliminates A, C and D because none of them refers to natural selection. Between B and E, E only deals with what ecologist once believed and doesn't state the author's view, namely that perfect adaptation will never happen in the author's view.

I hope this helps.

[siliconrs]

Look at the structure:

"After all" and "for" are used as premise indicators and both sentences that follow them support the first sentence not the other way around. The second sentence if anything is could be called a sub-conclusion.

[noah]

This offers a complex version of the classic ID the conclusion question argument structure (with conclusion in blue)

People say X.
They're wrong.
Here's why.

In this case it's:

It's wrong to say X.
Here's why.
Here's why that.

So, the conclusion is that it's wrong to say that natural selection will make perfectly-adapted organisms. Why? Because perfect adaptation is impossible - and the reason for that is that the environment varies.

As an earlier poster noted, the "after all" signals that the second sentence is a premise.

(B) correctly names the conclusion.

(A) is referring to a premise.

(C) is referring to a premise.

(D) is tempting, but it's referring to a premise too! Where's the reference to natural selection?

(E) is what the argument says is a mistake. It's a counter premise.

[andreperez7]

Does the semicolon at the end of sentence two function as a "after all", in that shows that the third sentence is supporting the second as a premise?

[Laura Damone]

Good question! Punctuation marks do sometimes indicate argument structure. Colons, just regular ones, not semicolons, indicate that what comes after them supports what comes before. But this is not consistently true for semicolons. Semicolons indicate a break between two sentences. Because they can be replaced with periods without changing the meaning of text, they don't tell us anything more about an argument's structure than a period would. And periods, I'm afraid, don't tell us much at all.

In this particular instance, the part of the sentence that follows the semicolon (no single set of attributes could prepare an organism to cope with all the conditions it could face) works in conjunction with the premise right before it (an individual's environment can vary tremendously) to support the intermediate conclusion (perfect adaptation of an individual to its environment is impossible). This, in turn, supports the main conclusion (it's a mistake to think that natural selection will eventually result in organisms perfectly adapted to their environments.)

Hope this helps!