Suppose that for a literature class, you and I are assigned to present and debate our interpretations of the novel Invisible Man. Our exchange starts promisingly with what appears to be a spirited clash of views. Later, though, and to our mutual mortification, it becomes apparent that you are offering an interpretation of the Invisible Man written by Ralph Ellison, while I am talking about a similarly named novel by H. G. Wells. What would happen at this point?

Well, I suppose that, overcoming the initial awkwardness, we might just proceed to offer our respective interpretations of the different books we have read. But we would no longer be engaged in a debate, and we would no longer be agreeing or disagreeing with each other. That is because in order to debate, and to agree or disagree, we must be talking about the same thing.

Fortunately, this sort of embarrassment could not arise with constitutional interpretation. Or could it? It is obvious, someone might observe, that when lawyers and judges and scholars and even citizens engage in constitutional interpretation, they are all talking about, and interpreting, the same thing – namely, “the constitution.” The observation is correct, I think, and also crucially important, and I will return to it later in this essay. But it is also true that this name or label – “the constitution” – might be variously used to refer to different things.