lawschoolplease1 wrote:FEB 96
section 4, #11.
Does "depends on" introduce a necessary condition?
If so, then the argument would read:
Premise: examine fossilized leaves of any prehistoric plant --> determine climate --> altitude.
Conclusion: fossilized leaf --> altitude
and this conclusion would be valid.
even before looking at the answer choices and question stem, however, i didn't feel 100% confident about my logic chain. i thought: it "depends on" the altitude, but is that equivalent to indicating an exact altitude? and when i got down to the answer choices, i was able to get to right answer by process of elimination and it "sounded right" to me (horrible way to pick an answer, i know).
So I was wondering... would anyone be willing to explain the correct reason? where am i going wrong with my logic chain?
thank you so much!
I wouldn't bust out so much formal diagramming on this one, but looking at your chain, I'd say the issue is that we know this:
examine fossilized leaves of any prehistoric plant --> determine climate, but we don't get that final "--> altitude" because the argument doesn't say that each climate has a unique altitude. "Depends on" usually does indicate that something is necessary, but here it's being used to say that climate is a factor, as in me saying that my mood depends on the weather. You wouldn't say "mood --> weather." This is another instance of when simply using key words for conditional logic can lead you astray.
Here's how I'd do this (I'm writing it up for our forums now, so excuse the broader tone of the explanation):
The conclusion of the argument in this ID the flaw question is that the size and shape of a leaf fossil indicate the altitude at which that leaf grew.
Why? Because the size and shape indicate the unique climate that the plant grew in, and climate is related to altitude.
This is a tricky argument in terms of finding the gap because it seems like a great argument if you're not careful. However, notice that the size and shape of a leaf are unique to a given climate, however, each climate isn't necessarily unique to an altitude. We only know that climate "depends on" altitude. Consider that velocity of a car depends on its mass and force applied (right?), however if a car is going 100 mph, there are no doubt various combinations of mass and force that could get there, so we can't deduce the car's mass (or force applied) from speed.
(B) hinges on this issue. Perhaps multitude altitudes have the same climate.
By the way, if you were thinking about what it means if the ground rises up because of tectonic plate movements, you were ignoring that the whole argument is about where the plant grew, not where the fossil was found.
As for the wrong answers:
(A) is out of scope 00 who cares about species surviving?
(C) is pointing out that there could be other ways to "read" a leaf to figure out the climate. Who cares? We're talking about one way.
(E) is tempting if you overlooked that the whole argument is about where the plant grew. Nowhere is the location of the fossil ever discussed. Out of scope.