#20 - The peppered moth avoids predators by blending into

[rachue]

Hi,

I see why D is correct here, that it targets the greater flaw in the argument, however I don't completely understand why E is wrong. Doesn't the argument make the assumption in E?

I'd appreciate some clarification. Thanks!

[Dave Killoran]

Hi Rachel,

The statement in (E) is too strong to be an assumption: the word "only" means this was the sole defense mechanism, but we just don't know that.

Part of the way we can see (E) as incorrect is because the author refers to likelihoods in the stimulus. This opens the door to having other methods of defense available (although the author would likely believe those other defenses were less effective than coloration).

Please let me know if that helps. Thanks!

[rachue]

But since the stimulus doesn't mention any other defense mechanisms, isn't that an assumption we take away? That blending was the ONLY mechanism? It was precisely because the author mentioned only the likelihoods of the blending mechanism, and drew the conclusion from the likelihood of lightly pigmented moths, that I thought the author was assuming that was the only defense mechanism available.

I'm still having a hard time understanding...

[Dave Killoran]

You can't make that assumption either way because there's no language that indicates that blending was the only mechanism.

Let me refer you to question #3 in Lesson 1, on page 1-11. They talk about three students in the waiting room; does that mean they are the only three students in the waiting room? Not necessarily (see answer choice (C), which is wrong). Same situation here...

[rachue]

That helps. Thank you.

[Dave Killoran]

If you have time, examine that L1 question closely--I think it tells you a lot about what you can and can't assume in these problems.

Thanks!

[rachue]

The similarity between the two is that we can only know what is directly stated in the premises, correct?

[Dave Killoran]

Yes, and equally importunately, we can't make any assumptions about what else is going on in the situation. In the case of the L1 question, there could be other people in the room but there doesn't have to be (or that there could be other people registered for the beginners tennis clinic, or not). That type of uncertainty is an area they mine constantly on this test.

[rachue]

That makes sense. Thanks.

[kappe]

please explain the correct answer. and whats is that I am doing that is not allowing me to see the issue