One may talk of a reliable car. “Reliable” here clearly means a car that has a high success rate of doing what it is supposed to (e.g. getting one where one wants to go in a reasonable time). One may also talk of a reliable source of information, that is, an authority. Can we understand reliability in a similar way here? Some people think that two concepts/notions of reliability are necessary. It seems to me that we can do with just one. An authority about something is just a person that has a high success rate of telling true propositions (/have a % justified beliefs) about the matter.
As an example think of Searle's chinese room example. Is the person in the room a reliable source?
“Imagine a native English speaker who knows no Chinese locked in a room full of boxes of Chinese symbols (a data base) together with a book of instructions for manipulating the symbols (the program). Imagine that people outside the room send in other Chinese symbols which, unknown to the person in the room, are questions in Chinese (the input). And imagine that by following the instructions in the program the man in the room is able to pass out Chinese symbols which are correct answers to the questions (the output).” (Searle, 1999, ‘The Chinese Room’, in R.A. Wilson and F. Keil (eds.), The MIT Encyclopedia of the Cognitive Sciences, Cambridge, MA: MIT Press. Found here.)
It seems to me that the answer is “yes”.
The other explication that has been offered of a reliable source is that “the person knows what he is talking about”. It seems to me that this is a constant phrase (i.e. one that is always used in almost the exactly same way). Such phrases are more often than not best understood non-literally. I suggest that a non-literal understanding/interpretation is a good idea. It could be understood as something similar to the general explication of reliability that I offered in the beginning of this essay.
However, one could insist that the phrase is meant literally and that reliability of persons /experts/authorities implies that the person knows. However it seems to me that the chinese room is a counter-example to this. The person in the room is reliable and does not know.
I also note that a non-literal interpretation/understanding is consistent with a fictionalist account of the field of the matter (e.g. an error theory about ethics) because one could use the notion of justified belief