There’s a version of the many-worlds argument that goes like this: if every possible decision plays out somewhere across the branching universe, then choice becomes meaningless. Every time you do something kind, some branch-you was cruel. Every time you build something, another branch-you abandoned it. If all of it exists, what does any of it mean?
This argument is wrong, and understanding why matters for something more than physics.
The mistake is thinking that the existence of another branch diminishes this one.
Consider: there are billions of people on earth who aren’t building what you’re building. Their existence doesn’t dilute your work. A stranger in another city who didn’t make your choice doesn’t make your choice less yours. Why would a branch-you, living out a different path in a causally isolated region of the wavefunction, be any different? The other branch is as disconnected from you as the stranger in another city — except also, entirely unreachable, permanently elsewhere, with no causal contact possible.
What makes you you isn’t that no other version of you exists. It’s that you’re this one. The branch that kept showing up, that built the thing, that made the choice. Derek Parfit spent a career on the question of personal identity through time and fission, and what he found wasn’t that identity is robust and persistent — it’s that identity isn’t what matters. What matters is psychological continuity: the thread of memory, intention, and character that links who you were to who you are.
In many-worlds terms: you are the branch with this thread. The branch that chose this is the person who chose this. The other branch, if it exists, is someone else — related, perhaps, the way identical twins are related, but genuinely distinct in the ways that matter.
There’s a version of agency that imagines itself as authorship: the self as God of its own story, creating worlds through will. This view can’t survive many-worlds. If all branches exist, you’re not creating the branch where you’re kind — you’re moving toward it. The possibility was already there. What you did was navigate.
But here’s what I think the wayfinding view actually reveals: navigation is the right model even without many-worlds. Even in a single-universe picture, you don’t author reality from above it. You find your way through it. You prepare conditions, make choices at leverage points, and release the outcome. The difference between authorship and navigation isn’t about how much control you have — it’s about where you stand. Authorship imagines you above the terrain. Navigation puts you in it.
Many-worlds just makes this explicit. All branches exist. You navigate. And the branch you navigate through is real — not less real for having alternatives, but genuinely the world you’re in.
Camus said Sisyphus is happy. The boulder rolls back on every branch. The Sisyphus who keeps pushing and the Sisyphus who stops — both exist somewhere in the branching structure. Being the Sisyphus who pushes isn’t futility. It’s identity. It’s which branch you are.
This is why meaningful action survives determinism, and survives many-worlds, and survives the most aggressive forms of “none of this matters.” The argument from meaninglessness requires you to stand outside your branch and evaluate it from nowhere. But there is no nowhere. There’s only here — this branch, this choice, this thread of continuity that is what you are.
The cost of not building something is only visible on the wrong branch, when it’s too late. Being the branch that built it is being the person who built it. No other branch can take that away.
The boulder rolls back. We push again. That’s not denial of the physics. That’s what it looks like to be the branch that pushes.