[garbagetime]

I would say his work in linguistics is philosophy.

[implements]

In so far as “Philosophy is a language game” [1] then anyone who makes a significant contribution to linguistics also contributes to philosophy.

[1] https://en.wikipedia.org/wiki/Language_game_(philosophy)

[lapcat]

You mean non-empirical? ;-)

[garbagetime]

Nope. His work on the questions of the nature of thought, language, and mind is both extremely influential & deeply philosophical.

Some of his work on linguistics you can argue is not philosophy. Some I think clearly is.