PT 60, S 3, Q 19, "One theory attributes..."

[cyruswhittaker]

I'm having trouble with this question. I initially chose A with the reasoning that perhaps the compounds by themselves don't show the effect, but they work together with appearance to avoid predation.

However, the answer is choice D, which states the flaw as since no individual member of a set has a certain effect (the individual compounds), that the compounds do not have the effect.

Is this perhaps because multiple compounds could be produced at a time, and hence have an aggregate effect not represented by the experiment (in which a single compound was tested)?

Please help me clarify this answer. Thanks

[bbirdwell]

You got it. The flaw hinges on consideration of individual elements (one compound per food pellet) versus the entire group together (all compounds), which is what is actually present in the butterfly.

Note that (A) is wrong because the argument doesn't make a judgement as to whether the first theory is wrong or right. It merely says there are two theories, and, because of this experiment, the second one is wrong.

[cyruswhittaker]

Thank you for the clarification. So just to make sure I have it right, would a flaw represented by choice A be simliair to the following:

"There are two theories, X and Y, for an event. We have proven that theory X is correct. Hence we also know that theory Y is incorrect."

So in this case, the argument would be flawed in that it presumed, without supplying justification, that the two theories are incompatible with each other. In other words, they couldn't both be true.

[bbirdwell]

Word.