Nick Bostrom, Department of Philosophy, Oxford University has written an interesting paper, Are You Living in a Computer Simulation.

This paper argues that at least one of the following propositions is true: (1) the human species is very likely to go extinct before reaching a “posthuman” stage; (2) any posthuman civilization is extremely unlikely to run a significant number of simulations of their evolutionary history (or variations thereof); (3) we are almost certainly living in a computer simulation. It follows that the belief that there is a significant chance that we will one day become posthumans who run ancestor-simulations is false, unless we are currently living in a simulation. A number of other consequences of this result are also discussed.

It is certainly the case that one of the 3 propositions has to be true, but the interesting one is (3) where, if it is true, Bostrom argues convincingly that most of us now are likely to be simulated minds.

The objection that actually being in a simulation undermines the simulation argument is addressed thus:

A. If we are in a simulation, then the underlying reality is such as to permit simulations, it contains at least one such simulation, and (3) is true.

B. If we are not in a simulation, then the empirical evidence noted in the simulation argument is veridical taken at face value, suggesting that a technologically mature civilization would have the ability to create vast number of simulations; and consequently, by the simulation argument, there is a very high probability at least one of the disjuncts in (1)-(3) is true.

Which seems an adequate rebuttal unless simulated reasoning is different from ground-zero reasoning – and nothing compels it to be the same; in this  case, the rebuttal only has meaning within the simulation, resulting in the possibility that A. may not be true outside the simulation, falsifying the rebuttal.

Going back to the 3 initial propositions, only (3) yields an interesting result; but is (3) possible? There are a number of problems. For (3) to be possible, “[a] common assumption in the philosophy of mind is that of substrate-independence” must be true. For it to be true, mind must be containable by the material: no part of the mind can be numinous. The Christian view is that a person, including the mind, is created in God’s image and, while it is dependant on the brain in this life, it will survive the decomposition of the brain in the next. From the Christian perspective, mind even though it uses the material, cannot be fully contained by it and  is, therefore, not substrate-independent in the sense used by Bostrom – it cannot be moved to a computer.

The second problem is found in the nature of computers themselves. If we take the non-Christian view that the mind has no existence outside of the material, could it be moved to a machine? In The Emperor’s New Mind, Roger Penrose makes the point that all digital computers now operate according to algorithms, rules which the computer follows step by step. However, there are things that cannot be calculated algorithmically. We can discover them and know them to be true but clearly we are using something – insight for example – other than calculation; they are so little understood that they cannot be duplicated by computers. In other words, current computers are elaborate adding machines with basic logic abilities; no matter how fast they run, they will be unable to create. A computer will never be able to algorithmically produce Bach’s Bm Mass or Dostoyevsky’s Brothers Karamazov without the works being part of the initial programming. It could be argued that, while ground-zero minds have creative ability, simulated minds do not but have been pre-programmed with the fruits of creativity and the ability to indulge in sufficient self-deception to believe they are the creative products of the simulated mind. If this is the case, though, the simulated minds would not be minds at all: they would be imitations, detailed simulacra unable to do anything other than follow their initial program.

So, although one of the three opening propositions must be true, it can’t be (3), even though (3) yields the best science fiction. Of the fiction noted on the simulation web site, Tad Williams’ Otherland series is  missing – it is one of the more entertaining series of novels to make use of this idea.

Perhaps the most pertinent conclusion one can draw from all this is that the preoccupations of modern philosophy are largely vanity.