Block-universe
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Day 4: Does the Future Already Exist?
Yesterday I left you with a question, today we are getting stuck in. If the block universe is right, and my death is already sitting in the loaf at coordinates I haven’t reached yet, then in what sense am I choosing anything?
It turns out this isn’t a new problem. People were freaking out about it 2,400 years ago.
Aristotle’s Sea Battle
Around 350 BCE, Aristotle wrote a short text called On Interpretation. Most of it is dry logic. But in Chapter 9 he stops to consider something that has been bothering philosophers ever since.
Imagine someone says: “There will be a sea battle tomorrow.”
Is that statement true right now?
It seems like it has to be either true or false. That’s basic logic. A statement and its negation can’t both be true. One of them has to be the case.
But if it’s true right now that there will be a sea battle tomorrow, then the sea battle is already locked in. The admirals can deliberate, the sailors can train, the ships can be prepared or not prepared, but the battle is happening, because the statement was true before they did any of that. And if the statement was false right now, then no matter what anyone does, no battle is possible. Deliberation is pointless either way.
This is the original fatalism problem. Aristotle didn’t have a block universe yet. He didn’t need one. He just noticed that if statements about the future already have truth values, the future is already decided.
His escape was to say: future-tensed statements don’t yet have truth values. They become true or false as time passes. The statement “there will be a sea battle tomorrow” isn’t true or false today, it just isn’t yet. Today’s truth is silent on tomorrow’s events.
That’s a tidy answer, and most philosophers since haven’t bought it. Bivalence, the idea that every proposition is either true or false, is hard to give up.
The Block Universe Version
Fast forward 2,300 years. Einstein hands us the block universe. Now we don’t need to worry about statements, we can talk about the actual thing. Tomorrow’s sea battle is sitting at its spacetime coordinates whether anyone says anything about it or not. Tomorrow’s you is sitting at its spacetime coordinates whether you’ve made up your mind or not.
So when you sit down at lunch and choose between the salad and the pizza, is anything actually being decided? Or is the salad-eating version of you already there in the loaf, and your “deliberation” is just the part of the loaf where the neurons fire?
This is the worry that makes the block universe feel like a horror movie.
Compatibilism, or: It’s Not as Bad as It Sounds
The standard response is associated with philosophers J.J.C. Smart and David Lewis, and it goes like this.
Yes, the future is fixed. But “fixed” isn’t the same as “forced.”
When we say tomorrow’s you eats a salad, what does that mean? It means tomorrow’s you deliberated, weighed the options, and chose the salad. The block universe doesn’t bypass your decision. Your decision is what’s written into the block. The reason the future slice shows you eating a salad is because the present slice, the one doing the deliberating right now, picks the salad.
You are not a passenger on a fixed track. You are part of the track-laying. Your choosing is a real causal node in the structure, not a piece of theater performed over a predetermined script.
Compare it to the past. The past is fixed too. Yesterday’s choices are locked in. We don’t usually feel like that’s a problem, because we remember making them. The block universe says the future has the same status as the past, with one difference: you don’t remember it yet.
This doesn’t fully comfort everyone, and I get it. The libertarian objection, made forcefully by Peter van Inwagen, is that genuine free will requires the ability to do otherwise. If the block already shows you eating a salad, there’s no sense in which you could have eaten pizza. Counterfactually, sure, in a possible world where your desires were different, you’d pick pizza. But in this world, the salad is already there. The pizza branch was never on the menu.
I find the compatibilist response more convincing than the libertarian one. But I also notice that I would say that, because I want to keep eating salad and feel like I picked it.
Quantum Mechanics Isn’t Going to Save You
A lot of people, when they first encounter this problem, reach for quantum mechanics. Surely the universe is fundamentally indeterministic at the smallest scales. Surely that means the future isn’t fixed, that quantum events ripple up into our brains and give us real openness.
This rescue doesn’t work, and the reason is sharp.
If your decision to eat the salad was caused by a random quantum event in your brain, then your decision was random. Randomness isn’t agency. If a quantum fluctuation makes your arm jerk and you punch someone, you didn’t choose to punch them. You twitched.
Indeterminism gives you unpredictability. It doesn’t give you authorship. Free will, if it means anything, has to mean you did it, not that a die was rolled inside your skull.
Some philosophers like Robert Kane have tried to thread the needle here, proposing that quantum indeterminism happens at moments of intense deliberation, and that the agent’s “effort of will” resolves the indeterminacy. I find this hard to believe, because it just relocates the mystery. How does the effort of will resolve the indeterminacy? If we knew, we’d be done. We don’t.
Tomorrow is not today’s set of problems, because today’s problems are in the process of being solved.
Sources
- Future Contingents - Stanford Encyclopedia of Philosophy (Aristotle’s sea battle)
- Fatalism - Stanford Encyclopedia of Philosophy
- Compatibilism - Stanford Encyclopedia of Philosophy
- Peter van Inwagen - Wikipedia (author of An Essay on Free Will, 1983)
- Robert Kane - Wikipedia (author of The Significance of Free Will, 1996)
- J. J. C. Smart - Wikipedia
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/ Philosophy / Physics / 30daysoftime / Free-will / Block-universe