While John D and Jack U are correct that the use of "authority" (A from now
on) doesn't decide the issue; I notice that they as well as most others on
the list make such appeals from time to time. And I think legitimately so.
1) If the question is what do those in authority say about an issue, then
quotes from authority are obviously reasonable.
2) If one makes an unsubstantiated assertion, then a reference to an
authoritative source is appropriate. (What I have done on the PE defined in
terms of work discussion)
3) It behooves any practictioner of science to pay great attention to what
authorities say. (Not blindly accepting). Otherwise we will have no
shoulders to stand on.
It behooves one for another reason, Joe Blow says he can show that perpetual
motion machines exist and he can prove it. He also tells you not to listen
to the authorities that say it can't be done. Do you spend lots of valuable
time on the question or not?