Dear Willard: Who needs words when one has letters and operators?

Peer-Reviewed Survey Finds Majority Of Scientists Skeptical Of Global Warming Crisis (Feb 2013)
http://www.forbes.com/sites/jamestaylor/2013/02/13/peer-reviewed-survey-finds-majority-of-scientists-skeptical-of-global-warming-crisis/

Regarding ad homininum (circumstantial)
Let X be AGW

1. Person A makes claim ~X.
2. Person B asserts that A makes claim ~X because it is in A’s interest to claim ~X.
3. Therefore claim ~X is false.

If Person B’s assetion is that ~X is false simply because the persons surveyed are petroleum engineers, I agree that argument is fallacious.

But there is a deeper problem. The author obscured the actual scope of the survey, so we aren’t even in agreement about the identity of “Person A”. And the identity of “Person A” has great relevance on the claim, since the whole op-ed is an argument from authority. In the beginning … “these skeptical scientists may indeed form a scientific consensus.” … and again in the end …”Now that we have access to hard surveys of scientists themselves” … much less the title of the piece … “Peer-Reviewed Survey Finds Majority Of Scientists Skeptical Of Global Warming Crisis”

How does the Forbes op-ed construct this consensus of scientists?
Through a fallacy of composition

1. A ‘consensus’ A makes the claim ~X OR ~Y
2. All A are an element of B
3. All B are an element of C
4. Therefore a ‘consensus’ of C makes the claim ~X OR ~Y

Where …
A is petroleum engineers from Alberta
B is geoscientists
C is scientists
X is ‘AGW’
Y is ‘crisis’
(note how Taylor mixes skepticism of causes (X) and consequences (Y) to construct his ‘majority’ and ‘consensus’)

The composition fallacy is more apparent when the actual group surveyed is revealed which is why it wasn’t and why noting the population surveyed isn’t fallacious. The source of the survey doesn’t prove/disprove ~X OR ~Y; it identifies the composition fallacy.