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Are you living in a simulation? Does it matter?

By Jack Walker - Philosophy Student @ Churchill College, Cambridge


The idea of a simulated reality is typically rolled out in philosophy to illustrate Descartes’ sceptical challenge to the possibility of knowledge – how can you know anything about reality if there is always the possibility that you are being deceived. If you are genuinely in a simulation, then the world you experience doesn’t really exist. Even if we think that there is some good evidence that we’re not living in a simulation, this is going to be of little use since that evidence could have been simulated too.

More interesting than the fact that we cannot rule out the simulation hypothesis, is the idea that we might have some positive reasons to believe that we are simulated beings. To this end, Nick Bostrom gives us his Simulation Argument. To begin with, we are asked to make two assumptions:

i. A sufficiently complex computer could manifest consciousness.

ii. Incredibly advanced civilisations would have enough computing power to run large numbers of simulations, even while using only a fraction of their resources for this purpose.

If we accept these, Bostrom says that three possibilities are open to us:

1) Humanity is likely to go extinct before it reaches an incredibly advanced stage.

2) Incredibly advanced civilisations are for some reason unlikely to run a significant number of simulations.

3) You are almost certainly living in a computer simulation.

The basic idea is that either advanced civilisations will never run these kinds of simulations because they will go extinct or for some independent reason, or that we are very likely living in a simulation. There are good reasons to doubt 1) and 2), which leads us to accepting 3).

However, given the difficulties in assessing their probabilities, Bostrom says that we should apportion our beliefs roughly equally between the three hypotheses. This argument alone leaves us with the unsettling conclusion that we are likely simulated beings, and that our world is not operating at the fundamental level of reality.

Another thing to recognise is that it might be possible for simulations to run their own simulations. However, as Preston Greene points out, the decision to do so must be taken very seriously since the consequences could be disastrous. Any computation taking place within a simulation must ultimately be supported by the basement level i.e., the genuine reality. This places a limit on what can occur within simulations since the computational capacities of the basement level world must be limited and would quickly become overwhelmed by stacks of different tiered simulations.

As a result, we should expect that any rationally created simulation would be terminated if its inhabitants got too close to being able to run their own simulations, for fear of the simulation becoming infinitely demanding, with each simulated world potentially hosting other simulated worlds. Based on this insight, Greene suggests that we should refrain from running our own simulations for fear that we might ourselves be simulated beings. To quote John Tierney writing on this issue, ‘We’d start our simulation, expecting to observe a new virtual world, but instead our own world might end — not with a bang, not with a whimper’.

What should we make of the possibility that we exist inside a virtual world? To many this idea will seem either so ludicrous or so fear-inducing to not merit much further thought. However, there are good reasons to believe that a virtual existence should seem neither far fetched nor terrifying to us. David Chalmers argues that the possibility that we are living in a simulated world shouldn’t really make that much difference to our lives. For Chalmers the world would still be real – just digital!

One final insight from Chalmers that is worth thinking about concerns the future of this technology. Whether we are simulated ourselves or not, interest in virtual reality is perhaps at an all time high. Facebook recently committed to the creation of a metaverse, understood as a genuine simulated digital environment. The worry here is that large corporations like Facebook are going to have the lion’s share of the power in creating, monitoring and conceptualising digital spaces. We run the risk of a future of simulated worlds, which are at best uninspiring and myopic and at worst, yet another tool to monitor and market to people. Despite seeming like a philosopher’s fantasy, conversations about the possibility and future of simulated life are hugely important if we want this technology to be as beneficial and liberating as it could potentially be.

Further Reading:

1. Bostrom, Nick. “Are You Living in a Computer Simulation?” Philosophical Quarterly (2003) Vol. 53, No. 211, pp. 243‐255.

2. Chalmers, David. Reality +: Virtual Worlds and the Problems of Philosophy, London: Penguin Books. 2022.

3. Greene, Preston. “The Termination Risks of Simulation Science.” Erkenn 85, 489–509 (2020).

4. Webb, Richard. “David Chalmers interview: Virtual reality is as real as real reality” The New Scientist, January 26, 2022,


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