Imagine you’re having coffee with your best friend; for the sake of discussion let’s call her ‘Basil’. According to common sense, the whole of Basil is present with you in the coffee shop. (If you’re facing her then you probably can’t see the back of her head; but it, and the rest of her, are before you nonetheless.) Now there is a peculiar philosophical position – known as ‘four-dimensionalism’ – which denies this datum of common sense. According to four-dimensionalism, you’re sharing the coffee shop with only one tiny bit of Basil. And that’s because Basil is spread out over time; she is a ‘spacetime worm’.
Suppose Basil was born in 1992 and will die (let’s be optimistic) in 2092. If four-dimensionalism is true, then the human being that is Basil is a four-dimensional object stretched out over these 100 years. And thus only one tiny slice of Basil, one ‘temporal part’ of her, is in the coffee shop with you. As four-dimensionalist Ted Sider vividly put it, if you wanted to embrace the whole of somebody, you’d have to cling to them from cradle to grave.
It is clear that four-dimensionalism is counter to common sense. But many philosophers believe that modern physics, in conjunction with various philosophical considerations, give us reason to think that it’s true. In this post I want to share my reasons for thinking the view cannot be true; or at least for sincerely hoping that it isn’t.
The basic argument is quite simple:
- My conscious experience is not the conscious experience of a spacetime worm.
- Therefore, I cannot be a spacetime worm.
There is at least one thing I know with certainty to exist, and that is my own conscious mind as it is right now. That thing which I know with certainty to exist – my conscious mind – is currently having an experience of a table with a laptop on it, beyond that a window, traffic outside, and a couple arguing in Hungarian in the next apartment. I am certainly not experiencing events of my childhood or of my life at the age of sixty four.
Now consider a Philip-like spacetime worm which is stretched across (let’s hope) seventy or so years of time. That Philip-like spacetime worm is certainly not having the experience I have just been describing; if it is conscious at all it is having some kind of weird consciousness involving all of the experiences of my life. But that is not my consciousness; it is not the consciousness of that thing which right now I know with certainty to exist.
In a recent article Josh Parsons has drawn attention to this point, but offers a solution: I am not a spacetime worm, rather I am a temporal part of a spacetime worm. The thing which has my conscious experience, the thing I know with certainty to exist, is just one tiny slice of the Philip-like spacetime worm stretched over seventy years of time. This is a coherent view, and it might be true. But I hope to God it isn’t. Because on the four-dimensionalist view such temporal parts do not exist for very long at all. Human-like spacetime worms are stretched through fairly long periods of time; enveloping many temporal parts. But the temporal parts which could be plausibly thought to have human experience last no more than a couple of seconds each.
Thus, if Parsons is right, then my conscious mind, that thing I know with certainty to exist, won’t be around in a couple of seconds’ time. It will be replaced by some other conscious mind which will be very similar to it, which will share its memories, but which won’t be me: the thinking, feeling thing I know with certainty to exist right now. This is precisely the content of the fear of imminent death: the fear that I won’t exist in the near future. If four-dimensionalism is true, then there is a very real sense in which I am dying every second.
It is not yet clear whether scientifically-based philosophy can provide us with overwhelming reason to believe four-dimensionalism. Until matters become clearer, I reserve my right to hope that four-dimensionalism isn’t true.