 The first debate concerns the reality of tense, that is, our division of time into past, present and future. Is time really divided in this way? Does what is present slip further and further into the past? Or does this picture merely reflect our perspective on a reality in which there is no uniquely privileged moment, the present, but simply an ordered series of moments? A-theorists say that our ordinary picture of the world as tensed reflects the world as it really is: the passage of time is an objective fact. B-theorists deny this. (The terms A-theory and B-theory derive from McTaggart’s (1908) distinction between two ways in which events can be ordered in time, either as an A-series—that is in terms of whether they are past, present or future — or as a B-series—that is according to whether they are earlier than, later than, or simultaneous with other events.)