The world is definitely real… right? If you’ve seen the Matrix, then you’ve probably asked yourself this question before. You’ve also probably reassured yourself that Matrix-like simulations are the work of science fiction; it’s just obvious that we’re not currently in one. This view isn’t shared by everyone, however. In fact, the idea that we – and the entire universe we occupy – are nothing more than simulations is becoming increasingly plausible.
Amongst those in favour of this simulation hypothesis are SpaceX founder and CEO, Elon Musk, who thinks it’s almost certain that we’re not in “base reality”, and world-renowned astrophysicist Neil deGrasse Tyson who believes the odds are more like fifty-fifty. Much of this is old news to those who are interested in such things (or just have a Twitter account, for that matter) but the argument behind these seemingly outlandish claims is a philosophical one and it’s pretty convincing once spelled out correctly.
The argument was first advanced by Oxford philosopher Nick Bostrom, who suggests that at least one of the following propositions must be true:
(1) Humanity is very unlikely to reach a stage where advanced, consciousness-containing, simulations are possible.
(2) Even if we find ourselves able to run such simulations, we would be very unlikely ever to do so – especially not on a wide scale.
(3) We are almost definitely living in a simulation.
The argument goes roughly as follows. We are currently seeing exponential growth in the computing power available to us and the forecasts of many technologists suggest that this will only continue. As such, it stands to reason that at some point in the future we will be able to create advanced simulations of entire universes – in fact, this future may not even be so far away (consider the sheer improvement in computing power over the past three decades alone).
If we were able to do such things, then we may wish to employ these simulations on a wide scale in order to study our ancestors and their lives. What’s more, it seems plausible that the humans present in these simulations would be conscious. Certainly, according to a common position in the philosophy of mind, consciousness is substrate-independent; this means that, whilst all consciousness we know of is exhibited by biological organisms, it could just as well be achieved by silicon-based processors inside a complex computer. As the physicist Max Tegmark puts it, there is no reason to believe that there is anything unique about “machines made of meat”.
With all this preamble in place, we can get to the heart of Bostrom’s argument. If it is possible to make many such simulations – and to make them consciousness-containing – then it certainly seems as if we could be in one right now. And it gets worse; basic probability tells us that if such simulations were to be implemented on a wide scale, then it’s not only possible, but exceedingly probable that we’re in one right now. Think of it this way: if many such simulations were created, then there could be trillions of humans ‘out there’ – some real, but most simulated. Unfortunately, this means that the probability that we’re a simulation (as opposed to the original species) is very high. An immediate reply usually goes along the lines of “yeah… but simulations haven’t been made yet so we’re clearly not one”. Regrettably, though, this is to beg the question – to claim that simulations haven’t yet been made is to assume that we ourselves aren’t in one, but as soon as we admit that they’re in principle possible it looks increasingly likely that we are.
Bostrom’s argument isn’t that (3) is correct, however, but simply that one of (1), (2), or (3) is. So, let’s look at (1) and (2) in an effort to escape the simulation. Consider (1):
(1) Humanity is very unlikely to reach a stage where advanced, consciousness-containing, simulations are possible.
If humanity is fated to go extinct before reaching the level of technological advancement required to begin simulating, then we may be able to escape the simulation-conclusion. If this is, in fact, an evolutionary pattern – if any human civilisation would be doomed to die out before reaching the required stage of technological advancement – then no simulations could ever be run. This may be hard to buy, however. It can’t just be the case that we might wipe ourselves out, but that any human society is destined to do so as a matter of its natural course. If this is the case, then, as Musk noted, it seems that (1) may actually be worse than (3). Proposition (2) may thus pose our only hope for a happy ending:
(2) Even if we found ourselves able to run advanced, consciousness-containing simulations, we would be very unlikely ever to do so – especially not on a wide scale.
This could come about in many ways. Maybe, once achieving the necessary level of technological advancement, humanity concludes that it is unethical to run simulations or to subject any sort of consciousness to the ‘barbarity’ of the past. As attractive as such an idea might be, however, it doesn’t – at least on the face of it – seem as if we would have many ethical qualms about simulating the consciousness of people living thousands of years ago. Perhaps we wouldn’t simulate our recent ancestors, but what about the very first homo-sapiens, those that lived hundreds of thousands of years before us? This could very well be how our technologically-advanced ‘descendants’ view us.
Here’s a more out-there way that (2) could be vindicated. It’s possible that any advanced human society would be aware of the simulation hypothesis laid out thus far. In fact, if they had created a simulation, truly believed that it would work, and there were no rules about turning it on, they could be almost certain that they themselves were in a simulation. They may then realise that running simulations within simulations would require a huge amount of processing power on the part of their own simulators and, worried that they would simply be ‘turned off’, never run the simulation themselves. This is somewhat paradoxical: nobody ever runs simulations because they’re constantly paranoid about being in a simulation, but this itself becomes the exact reason that they’re not! You might find this even more unlikely.
But there you have it. Maybe nothing’s really real: if we’re not currently in a Matrix-like simulation, then our descendants will probably never run one. Either way, it doesn’t seem like we’ll change the way we live our lives. Perhaps, then, for sanity’s sake, it’s best to look the other way.