My question takes as an assumption that using sources as authorities is a practical necessity even while acknowledging that appealing to an authority can be considered a logical fallacy in deductive argumentation.
In some contexts it is an accepted practice to cite the claims or works of other people, and in others it is not. I find it a perplexing problem to decide on a method to assess whether to accept a source as an authority because I have not been able to develop a method that is both universally-applying to this problem, and can be demonstrated as generally reliable when tested. I have considered that it may be necessary, or at least more useful, to classify proposed sources and use different assessment methods for different classes to optimize reliability.
Here is an unordered list of heuristic questions I have considered:
Do the people pertinent to the source have verifiable credentials?
Do the people pertinent to the source have a record of fraudulence?
Do other verified authorities, assuming that any can be established, cite the source as an authority?
Do the people pertinent to the source have the same view as the consensus view of other verified authorities? [Assuming there is a consensus and that there are other verified authorities]
I feel that this list is not well-formed, and incomplete, and I would appreciate input from other skeptics on how to approach the issue of assessing whether to treat sources as authorities.