As I mentioned last time, there are both causal and non-causal varieties of determinism. Most people think of determinism only in terms of the former: events are determined, they might say, if they are the result of prior states along with strict laws of cause and effect (so that given those prior states and laws, the events could not have failed to occur). But historically there have also been arguments for determinism that have nothing to do with causation, such as logical determinism and the type of theological determinism based on God’s foreknowledge (as opposed to God’s foreordination).
I’ll return to theological determinism next time. Today, I want to talk about a much less well-known kind of non-causal determinism.
According to the theory of relativity, there is no absolute “now,” or present moment. What for you are two simultaneous events won’t necessarily be simultaneous for someone else. So, for instance, take what is going on in a galaxy far, far away at the moment you are reading this. There are events occurring there that, from your perspective, are occurring right now. You can’t know about them yet, of course. If the galaxy is, say, 2.5 million light years away, then you have to wait 2.5 million years for its light to reach us. But if you look at it then, you will see what was happening there at the time you were reading this (approximately). However, you can’t say that those events that for you are occurring right now are occurring right now in any absolute sense — because for someone else right now who is travelling relative to you, what is going on in that galaxy will be some other set of events. But that means the universe as a whole cannot be absolutely divided at each moment into past, present and future.