PTA.S1.Q13 - dirty stone building vs. clean one

Darklord

Hi,
Does anybody here know why the answer is D and not E?

Admin note: edited title; please use the format of "PT#.S#.Q# - [brief description]"

taschasp

The flaw in the architect's argument is a "fails to consider" one. The architect fails to consider that buildings could be cleaned with something other than water, which would render the whole conclusion false. D is correct because the engineer specifically points out what the architect failed to consider, by citing some new facts--which is what "adducing facts selected" means. Though I will say, I don't think the LSAT uses this kind of language anymore, so if that was what got you caught up, I wouldn't worry much about it (seriously, who says "adduce" anymore?)

E is incorrect because the engineer is not "using the evidence cited by the architect to draw
an alternative conclusion." This answer choice implies that the engineer would be using the SAME evidence to draw a different conclusion, whereas in the argument, the engineer is clearly adding in new evidence which forms the basis for the different conclusion.

Darklord

Ok wow thank you!!

taschasp

Anytime glad to help!

Darklord

Wait, but for answer choice E, isn't the engineer technically using evidence that the architect uses (ie the fact that stone buildings don't like water) to come to a different conclusion? Asking because even if I wasn't sure if D was correct or not due to the unknown definition of "adduce", I want to at least fully understand why E was wrong.

taschasp

Is the engineer using that piece of evidence (that stone buildings don't like water) to draw a different conclusion? Or is he using a new piece of evidence to do so?

Remember, the question is asking what the engineer does in order to respond to the architect. It's not enough to say he cited the evidence of the architect. He clearly did acknowledge it. But that's not what led him to the alternative conclusion. He reached the alternative conclusion because of something else, which was the fact that you could actually clean these buildings without using water.

taschasp

More abstractly, the architect says: "because B, we can conclude C".

The engineer doesn't say, "I agree that B, but based on B, we can actually conclude X (alternative conclusion)."

Rather, the engineer says, "I agree that B, but you're taking for granted A which is actually wrong; because of Q, B doesn't actually really matter, so C is false."

A = assumption that water is the only way to clean a building
B = dirt damages stone buildings less than water
C = stone buildings must remain dirty if they are to last as long as possible
Q = advances in technology allow cleaning buildings without water

Darklord

Hmm... that makes sense-- thank you!