Philosophically (and perhaps linguistically, what is the difference between the question, "who are you?" and "what are you?". To answer the former, I often describe something about myself like my name or that I'm a student. The latter is often posed to me when people ask about my ethnicity or national origin. And perhaps more broadly, how do we "know" which sorts of identifying information is pertinent in answering either? Thanks, and great site.

One way that you might distinguish "What are you?" from "Who are you?" is to take the former question to be asking what kind of thing you are (e.g., a rational animal), and to take the latter question to be asking what distinguishes you from other (maybe, every other) member of your kind. When someone asks you one of the questions, you have to rely on context to decide what information is being asked for. Like you, I generally take "What are you?" to ask for more general information than "Who are you?"

This is a question about Hilary Putnam's twin earth thought experiment. After I read this thought experiment I was not convinced that Oscar's and twin-Oscar's "water" concept have different meanings. But most of the philosophers' intuitions are similar to Putnam (i.e., they think that Oscar's and twin-Oscar's "water" concept have different meanings). I thought that there might be something wrong with me. So I told this thought experiment to different people with different origins but without exception all of them responded that both Oscar's and twin-Oscar's "water" concept have the same meaning. So I still do not understand, why do so many philosophers' intuitions work like Putnam's? Thank you, Deniz

'Water' is a natural-kind term, and the natural-kind that 'water' refers to turned out to be H2O. In every possible situation, 'water' refers only to quantities of H2O. Twin-water is of a different natural kind, say, XYZ. The idea is that physical natural-kinds are defined by what they are made up of. So, the stuff made up of XYZ (and not H2O) is not water. The intuition that the XYZ-stuff on twin earth really is water may come from considerations like these: The XYZ-stuff on twin-earth looks and tastes just like water; it is used in the same way that we use water (brush teeth with it, wash clothes in it, etc.). But what determines the meaning of a physical natural-kind term (it is thought) is its physical make-up, not how it looks or what it's used for. How it looks and what it's used for "fix the reference" of 'water:' The stuff that looks like *that* (pointing on earth to H2O) and is used for teeth-brushing, etc. is water. It turned out (centuries later) that that stuff is H2O-...