Simulation hypothesis

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A technologically mature “posthuman” civilization would have enormous computing power. Based on this empirical fact, the simulation argument shows that at least one of the following propositions is true:

(1) The fraction of human-level civilizations that reach a posthuman stage is very close to zero;

(2) The fraction of posthuman civilizations that are interested in running ancestor-simulations is very close to zero;

(3) The fraction of all people with our kind of experiences that are living in a simulation is very close to one.

If (1) is true, then we will almost certainly go extinct before reaching posthumanity. If (2) is true, then there must be a strong convergence among the courses of advanced civilizations so that virtually none contains any relatively wealthy individuals who desire to run ancestor-simulations and are free to do so. If (3) is true, then we almost certainly live in a simulation. In the dark forest of our current ignorance, it seems sensible to apportion one’s credence roughly evenly between (1), (2), and (3).

—Nick Bostrom, Are You Living in a Computer Simulation? (2003)

I wish I could summon a strong argument against it, but I can find none.

— Neil Degrasse Tyson

“I speak of none but the computer that is to come after me,” intoned Deep Thought, his voice regaining its accustomed declamatory tones. “A computer whose merest operational parameters I am not worthy to calculate—and yet I will design it for you. A computer that can calculate the Question to the Ultimate Answer, a computer of such infinite and subtle complexity that organic life itself shall form part of its operational matrix.

— Douglas Adams, The Hitch-Hiker’s Guide to the Galaxy

An amusing, but fundamentally preposterous a priori argument which purports to prove by deduction, in the same way that Rene Descartes deduced the existence of rice pudding and income tax, that either we are as good as dead, or we live in a Matrix.

Spoiler: a priori arguments are conjuring tricks. They are fun and entertaining. but don’t try them at home. This one is practically impossible to try at home, of course, which is, perhaps, why apparently intelligent people who ought to know better, like Neil deGrasse-Tyson, are sucked in by it.

The argument

1. If you accept a materialist perspective, and you have a sufficiently powerful computer, you can emulate human consciousness.
2. if you can emulate human consciousness, you can simulate the existence of people like your forebears.
3. A sufficiently fine-grained, conscious, simulated human would be unable to tell itself apart from an actual biological human, and vice versa.
4. if your computers are powerful enough you can run a great many emulations of your forebears.
5. if you ran enough emulations, simulated humans would vastly outnumber actual humans.
6. if simulated humans vastly outnumbered biological ones and one could not tell whether one was biological or simulated, a rational human should assume itself to be simulated.

To help Professor Degrasse-Tyson, here are some strong arguments against the simulation hypothesis:

We are the dead

To take the simulation hypothesis to its logical conclusion — a reductio ad absurdam — you don’t need to travel very far, and you conclude intelligent life capable of creating a Matrix is logically impossible, and we are, therefore, dead — or at any rate well on the way to being dead. Then again, if you can do it, then you are a simulation, and you aren’t biologically alive either. If you can’t do it, then — clearly — you can’t be a simulation, but you must also be incapable of developing a difference engine that could create a Matrix, so you wouldn’t be having this conversation in the first place. We know we aren’t dead, so we must therefore be in a Matrix.

Deep Thought successor redux

But, problem: unless intelligent life becomes capable of simulating itself — that is, creating a Matrix — there can be no Matrix. The definition of a Matrix is that it is a simulation of intelligent life. If there is no intelligent life to simulate, then, whatever a Matrix is, it can’t be a simulation. Matrices are clever, but they can’t bootstrap themselves into existence — not if you want to stick with your materialist assumptions we made earlier. If there is a Matrix, there must be intelligent biological life to have invented it.

But wait: could the Matrix be — the real thing? Like, could the Universe itself be some kind of super computer?

We call this the “Douglas Adams objection”: once we get hip to substate neutrality, isn’t the universe itself a giant computer? If so, what need of a simulation? Doesn’t a copy of the universe, doing what the universe is already doing by itself, fall rather foul of Occam’s razor? Have we just proved that life exists? If so, then I have some news, fellows: someone beat you to this splendid a priori idea by 400 years: Rene Descartes. Is not the simulation hypothesis another way of saying, “cogito, ergo sum”?

When the JC was a lad his Dad, Old Grumpy Contrarian, went snorkelling off a boat in the Ionian Sea. After a while the old man emerged, declaring triumphantly he had found an ancient anchor on the sea bed: a relic, no doubt of Siege of Troy, or the Odyssey. The whole Contrarian family was very excited. T“here is a warp tied to it!” Grumpy exclaimed, excitedly disappearing below the waves with another colossal splash. Bravely he followed the anchor warp for twenty yards across the sea floor, until it rose up, into the warm upper waters, broke the surface and revealed itself to be — attached to the runner over the prow of his own boat.

Real life meets the definition of “a computer simulation”, especially if you go substrate neutral

For this to work, the simulation would not just have to be very good: it would need to be identical to real human sentience, in every respect. Any shortcuts would lead to potential variances, and as we know from our modern morality tales about, butterflies and rain forests, jointed pendulums and so on, any atomic variations in initial conditions have colossal, non-linear knock-on effects.

This would involve not just a perfectly accurate — that is to say transcendently true — theory of human cognitive activity, but a perfectly accurate — that is to say transcendently true — theory of all events in the universe. These theories would not be models as any sense of the word, but actual replications of the actual world, that is to say, the territory itself, not a mere map.

So firstly the sheer computing power required to run this algorithm would be so great as to not only be practically impossible, but theoretically impossible. In fact, its operation would not so much skew the functioning of the real-world, but but duplicate it: but but you cannot duplicate the energy in a closed physical system without violating the laws of thermodynamics.... unless the real world counts as a computer simulation. which on this logic it does. If a computer simulation is indistinguishable from the universe itself, then the universe is the computer simulation and this hypothesis is — semantics.

And about those laws of thermodynamics: in order to draw a complete, functioning, comprehensive theory of the universe, one must first have comprehensive, true, knowledge of the total canon of all laws of science. But science being an inductive process, and quite incapable of establishing anything by way of proof, this is again theoretically impossible. Our present state of knowledge of the laws of the universe is contingent and incomplete.

See also

• The Hitch-Hiker’s Guide to the Galaxy
• Substrate
• A priori
• Rene Descartes