Thought of a sample case that suggests that ordinary language as a direct source of philosophical truth is either wrong-headed or more complicated than the name suggests. I was looking at a story about the ship of Theseus and started thinking about the paper title “A sweater unraveled” (which I have not read).
I thought about someone holding up a pile of yarn and saying “Look at my sweater!!!” Someone might say “We say ‘Look at my sweater!!!’ when displaying an unraveled sweater; therefore the yarn is the sweater, even though it is unraveled.” That doesn’t seem right. I’d say it is more complicated than that.
For one, one might argue that what is meant is “Look what happened to my sweater!” or “This is all that is left of my sweater!” In neither case is it implied that the yarn is the sweater. I think one could argue that because these meanings seem roughly interchangeable, “what we say” seems ambiguous in its logical implications.
Another interpretation of this gesture also doesn’t really seem to support the view that “what we say” settles the matter. It might make sense to say that we do consider the sweater to be the pile of remaining yarn, but not because of the interjection “Look at my sweater!!!” It seems reasonable to make some set of claims about “the sweater” being a functional concept that covers the pile of unraveled yarn. For example, the owner may handle the pile in a special way that suggests it is not “just” a pile of yarn, especially if she thinks it can be repaired, returned to a store, used in a lawsuit, etc.
You could make such arguments. But then you’d probably only want to if you were paid to be a philosopher. And only others paid for similar reasons would probably want to read such things.