It's only fallacious when we refer to an improper authority like referring to the local pastor on the latest scientific discoveries.
I disagree. An appeal to authority is fallacious when we say that something must be true
because Mr./Ms. X said it is. It doesn't matter if this is a "proper" authority or not.
Who who says something has no
logical baring on it's truth.
Of course, separate from the logic it is reasonable to expect an experts pronouncements to be more likely true than someone who knows something but that is only a first cut at the issue.
It is
why they say it that really counts.
Edited by NosyNed, : No reason given.