Reality+ - David Chalmers ***

Embarrassingly, I read and reviewed this book back when it came out in 2022, but forgot I had when I wanted to read more about the simulation hypothesis and virtual reality as it's a topic that comes up when considering multiverses - but originally I focused more on it as a piece on VR, where this time I was more focused on the simulation hypothesis. I've written a new review, but in case you want to see if my opinion has changed (it hasn't much) I've included the old review below.

David Chalmers uses the idea that we might be living in a computer simulation, rather than a real universe, to explore a number of philosophical queries. Initially I was really enjoying his approach, bringing in pop cultural references (the inevitable Matrix but various others too), though the cartoon illustrations are somewhat painful. However, after a while we seemed to lose sight of the deeper philosophical applications to provide a heavy going manifesto for our digital existence.

Chalmers argues both that we are likely to live in a simulation and also that virtual worlds are real, not illusion, just differently formed to the universe of matter. He is clearly passionate about these beliefs, but I did not find either convincing. To be fair to Chalmers, he does present alternative views from other philosophers, but inevitably he suggests his viewpoint should triumph.

Part of the problem is that while Chalmers accepts there are many physical limitations on simulating something as complex as a universe and human brains (particularly with added consciousness), he hand-wavingly gets us around these by assuming computing technology will continue to advance indefinitely, and, if necessary, quantum computing will fill the gaps, conveniently overlooking the reality that quantum computers aren't and never will be general purpose devices, nor are they likely to be able to simulate a single whole brain, let alone billions of them.

Chalmers is also an enthusiastic user of virtual reality, and like all enthusiasts for a particular technology is convinced that everyone will adopt it in the future. But in some of the examples given, I'm not sure it's true. I can enjoy a film, for example, in which people are shooting each other - but I wouldn't want to be immersed in it. Often I prefer a book to a film, let alone VR, because it's a less crude form of immersion. I'm sure VR and particularly AR (augmented reality, which Chalmers also covers more briefly) will become more popular with the move away from clunky visor-like headsets, but his viewpoint seems extreme.

Underlying the argument that we are likely to be living in a simulated universe is a very shaky application of statistics, not unlike the inverse gamblers fallacy used to argue for multiverses. It says that if (big if) it's possible to simulate a universe, then it will be done lots of times, meaning there are far more virtual than 'real' universes, so chances are we are in one. But even if (big if again) it were possible, it's an assumption that the envisaged super-civilisation would want to make all these incredibly complex simulations. Even Chalmers admits that if you use this kind of argument you could also argue that the vast majority of simulations would be a lot less complicated than our universe appears to be - but doesn't follow through with the logical conclusion using the same kind of argument - if the vast majority of simulations are simpler than our universe, chances are we aren't in a simulation.

I didn't mind disagreeing with his arguments - that's part of the fun of philosophy - but I did feel that after a while it all got rather samey, where I would have liked to have seen an examination of wider philosophical issues. Glad I read it, but it certainly hasn't changed my mind.

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2022 REVIEW

Thanks to major IT companies putting a lot of time and effort into it (not to mention changing their company names), virtual reality is rarely out of the news at the moment. So it's timely that David Chalmers should attempt an exploration of the nature of virtual reality. What he sets out to persuade us is that 'virtual reality is genuine reality'. That virtual worlds don't have to be illusory, the objects within virtual worlds are real, life can be good and meaningful in a virtual world and that the simulation hypothesis - the idea that what we usually think of as reality could itself be virtual, while not provable could be true.

I became a little wary early on as Chalmers is clearly a virtual reality enthusiast: he tells us he has 'numerous virtual reality systems' in his study. This is not normal. You might think from all the hype that everyone except you is an inhabitant of virtual worlds, but it's still a pretty small minority - around the 1 per cent mark in the UK - and there highly focussed on young gamers. Until the whole business is far less cumbersome and more high quality, I can't see it becoming mass market. (Remember when everyone was supposed to be watching 3D TV within a few years. That went well.)

However, while I don't agree with Chalmers on the idea that VR will soon be ubiquitous, I was still interested to see his arguments. Unfortunately, they turned out to be classic waffly philosophical ones. There was never any convincing evidence, for example, that VR was in any sense real - in the sense, for example, that without necessarily being able to vocalise it, we know what reality is and it should not be capable of being switched off. In a sense this issue reflects the nature of philosophy. I can define an object in a way that requires it to be made of atoms: quite clearly then it is not true that objects in virtual reality are real. That doesn't make me right - but equally it can't be countered.

I'll be honest, I found the constant philosophical noodling tedious - this is real 'how many angels can dance on the head of a pin' territory. (Funnily enough, there is little evidence much time was ever spent discussing angels and pinheads in reality - by which I don't mean virtual reality.) Because of the VR context I had expected more scientific basis for the content, but there was very little that went beyond attempts at proof by argument rather than evidence. The handwaving felt distinctly frustrating, but I suppose it's the nature of philosophy.

Chalmers had an interesting idea to explore virtual reality's relationship with true reality - and the book is worthwhile because of that - but I didn't feel I had learnt much at the end of its 450+ pages.

Review by Brian Clegg - See all Brian's online articles or subscribe to a weekly email free here