How do words achieve their function of allowing communication between two speakers of a language?
Words gain meaning through work. That is, one must create the concept associated with a word, and make sure two speakers share enough of the concept that they can communicate. (One can imagine how this might occur piecemeal.)
In novel or rare situations for word usage, a consensus on the concept may not be there. That is, the ‘core’ concept may not speak directly to it.
Take ‘dog’. Now imagine that you start changing the genetics of things we take to be dogs today. At what point does it stop being a dog? There is probably no sharp consensus, because this is a novel situation that the concept hasn’t been created to deal with.
If it became important, we could then innovate on the concept, creating new distinctions so that the word ‘dog’ could be used to communicate relatively clearly. (We would ask: “What is important to us about the concept ‘dog’?”)
This makes many debates in philosophy moot. Consider what the word ‘know’ means. People use the word to do things, in situations that come up every day. If, as a philosopher, you conjure some strange situation and then ask people whether someone ‘knows’ something or not in such a situation, there might be no consensus to the concept that has been worked out. You might get differing intuitions, or people might say they don’t know.
As far as these sorts of thought experiments are doing anything, what the philosopher is doing might be seen as instigating new conceptual construction. “Let us innovate on this concept, so we can solve this conceptual problem …” (such as at what point in genetic change we should stop calling something a ‘dog’). That is, most debates about what the meaning of words ‘are’, are actually debates about how to change the concept of a word. “What is the way to innovate on this concept so as to solve this problem?”
(Of course, some concepts refer to things, and the conflict is about some aspect of that thing. For example, if we want the concept ‘dog’ to refer to animals with a genetic code similar to the animals we paradigmatically call dogs, what kind of genetic code is that? If we don’t already know, we will have to investigate to find out.)