Now in any field there may well be experts with controvesial opinions, if they are speaking about their field how does one deal with an appeal to their authority in an argument?The Appeal to Authority uses admiration of a famous person to try and win support for an assertion. For example:
"Isaac Newton was a genius and he believed in God."
This line of argument isn't always completely bogus when used in an inductive argument; for example, it may be relevant to refer to a widely-regarded authority in a particular field, if you're discussing that subject. For example, we can distinguish quite clearly between:
"Hawking has concluded that black holes give off radiation"
and
"Penrose has concluded that it is impossible to build an intelligent computer"
Hawking is a physicist, and so we can reasonably expect his opinions on black hole radiation to be informed. Penrose is a mathematician, so it is questionable whether he is well-qualified to speak on the subject of machine intelligence.
Of course you can name opposing experts, but that just leads to a stalemate.
My intuition is that an argument based on facts and logic cannot be over-ridden by an appeal to a authority, but I don't know what type of fallacy this would be - if it is one. Without going into a big debate into facts/logic versus expert opinion everytime this arises, is there any way to deal with a quoting of a relevant expert opinion in refutation to an argument based on facts and logic?