There's certainly a clear distinction between "definition" and "semantics". They are -- to echo PeterJ -- in different categories. In his evening talk on Post some LICS' ago, Martin Davis told us of his sense of revelation when he learned he'd been a computer scientist all these years. Now I know just how he must have felt. What a relief to find I have *not* been a semanticist all these years. All I ask is a tall ship and a star to steer her by. Definitions tell us our position relative to both our destination and the rocks of inconsistency. Whatever semantics is, if the navigator says he can't do his job without it we're lost. Another round of semantics for the navigator. let's start with the Church polymorphic notion of number. Of course when the navigator's had so much semantics he tells you he's seeing double, you do worry a bit. That semantics is heady stuff. Vaughan Pratt