[kbp]

Clojure isn't Lisp because it doesn't run Lisp programs and has different syntax and semantics to Lisp. McCarthy's original Lisp, Lisp 1.5, Maclisp, Emacs Lisp, Zetalisp, Common Lisp, EuLisp, etc, can share nontrivial programs written for each other with little to no modification; that's why people talk about them as versions of the same language. That doesn't hold at all for Clojure.

That isn't a complaint about Clojure at all, Clojure is a really cool language and does some things better than Lisp, but it's just not a Lisp, it's a Clojure. It borrows some syntax from Lisp in the same way that Java borrows some syntax from C, and it makes about as much sense to refer to Clojure as Lisp as it does to call Java C.

If you want to say that Clojure uses sexprs for source representation, say that; if you want to say that Clojure has dynamic typing and lexical closures (the latter of which most Lisps have not had), say that. Calling it "Lisp" to mean whatever handful of features that you personally think are the defining elements of Lisp doesn't aid clear discussion.

[rpeden]

That's a reasonable way to look at it, and I think we mostly agree. I personally don't call it anything other than Clojure. :)