Definitions -- Ostensive or Authoritative?

Inspired by any number of threads:

People ask: “What is an ‘X’?” (actual ideologies supressed as much as possible to avoid recriminations). There seem to me to basically be two ways of answering that question:

Method #1: Find a bunch of people who style themselves “X”, follow them around, see how they behave, and then say, “An ‘X’ is the sort of person who does ‘A’, ‘B’, and ‘C’”.

Objection #1a: A lot of other people who claim to be “X” will say, “Oh, but they aren’t real ‘X’!”.

Objection #1b: A lot of people (some of whom who may not even claim to be “X”) will say, “Oh, but you’re confusing coincidential behaviors with ‘D’, which is the real essence of ‘X’”.

Method #2. Find “N” who claims to be (or is widely recognized as) a guru of "X’, and read his statement that, “An ‘X’ is the sort of peraon who does ‘E’ and ‘F’”.

Objection #2a: Some (perhaps many) who claim to be “X” will say, “Oh, but ‘N’ is a heretic” (or perhaps more broadly, “doesn’t really represent the majority of ‘X’”).

Objection #2b: Some (who may not style themselves “X”) will say, “Oh, sure, ‘N’ claims that ‘X’ will do ‘E’ and ‘F’, but we really know that ‘X’ do ‘G’, instead”.

What think ye? Is there a third method that I am missing? How do we determine what “X” really is?

My solution: Crack open that dusty ol’ dictionary. Man, that thing is just chock full of nifty information!

For situations about subjective matters, then it gets tricky (and I’m assuming this is mostly what the OP is referring to). For those situations, I always say that there’s a certain “core substance” that X must have (let’s call it S), and then there’re some “Gray Areas” (G) which can be included.

To wit: X = S + G1 and/or G2 and/or G3. Not so much as stating a requirement for X, but stating the bounds that X must fall in.