I've been reading some online articles on the concept of "function", but I'm not very sure about it. An ashtray, according to my dictionary, is a "container for cigarette ash", but I don't know what this "for" means. It can't mean that people ought to put ashes in the ashtray, because there are other places where we may put it. And it can't mean that people may put there the ashes, since, once again, we may put the ashes in places which are not ashtrays. It can't either mean that the ashtray was made "with the purpose" of serving as a container for the ashes, because an object may be an ashtray now but haven't been made to be an ashtray. So, what is an ashtray?

Your question suggests that answers to the question “What is thefunction of X?’ will have normative implications about what we ought orought not, may or may not, do to Xs. And this fact is puzzling. How,you might be wondering, can certain facts about an object’s functionhave any implications about what I may or may not do to it? And I thinkthat you are right to be skeptical: in the case of ashtrays, functionaldefinitions have no normative implications for us– about what we may ormay not do to them. However, behind your question may be Aristotle’s “function argument” in the Nicomachean Ethics (I 7), where he argues that information about the “function” ( ergon ) of humans has implications for what sort of life humans ought to live-- “ought”, that is, if they are going to be well off. Onmy view, Aristotle’s notion of function does not correspond to any ofthe three notions of function that Nick distinguishes for ashtrays. Todistinguish Aristotle’s notion from those that Nick defines, I’ll...