“3:AM: So one of the big issues in science and metaphysics that you have looked hard at is time and implications running from different conceptions of time. There are several philosophically interesting and paradoxical seeming things about time. McTaggart‘s arguments about the unreality of time is a pretty cool argument. He basically argues that time doesn’t exist because the past doesn’t exist because it’s finished, the future doesn’t exist because it hasn’t happened yet and the present doesn’t exist because to understand the present you have to relativise it to the past and the future. Given that they don’t exist time doesn’t exist. You have recently asked the question whether time is an illusion. So is it? If not, what is it and what isn’t it?
Craig Callender: We all seem to possess a kind of proto-theory of time. Let’s call it manifest time. Manifest time says that time has a global, shared present that is metaphysically distinguished. This present carves the world into three, a past, a present and a future. This present flows. It is intrinsically directed. It is independent of the distribution of matter. And so on. No matter how scientifically literate, I bet the reader shares this theory. Think of how important this conception of the world is to you! The way you live your life depends crucially on it. What you take yourself to cause, know, your very freedom and sense of self are all bound up with this conception of the world. Manifest time really is, as the philosopher Mellor calls it, the time of our lives.
Yet physics tells us that this picture is more or less complete rubbish. I believe that. That is, I don’t think, merely by sifting through the physics, you’ll be able to recover manifest time.
Does that mean that physical time is inaccurate or incomplete? No, physical time may be all the time we need, fundamentally. However, it may be that by looking at more than physics we can explain why a creature embedded in a physical world such as ours would conceive of the world as we do in terms of manifest time. That is, I think that we can show why manifest time makes sense for creatures like us. I talk more about this project of getting from physical time to manifest time in the book I’m currently writing. The idea is that physics provides important constraints on any being like us, and these constraints, in concert with our psychological mechanisms, means of communication, macroscopic environments, and senses of selves, all together explain why we conceive of the world in terms of manifest time.
Is manifest time an illusion? In one sense, yes: manifest time is not accurately representing physical time. But there is a sense in which a world without perceivers lacks colors; only when perceivers are around do colors obtain. (Alternatively, maybe the colors exist as dispositions to look colored if an appropriately configured perceiver is present.) Either way, we don’t regard colors as illusions. Maybe some aspects of manifest time are like this, in which case we wouldn’t judge them as illusions. Embed a creature like us in a world like ours and that triggers a sense of flow, say. Once you break down manifest time into its various components, it becomes a bit tricky whether we ought to say its illusory. What I can say is that I don’t think manifest time maps onto the fundamental picture of time we have from physics.”