Why It's a Good Bet that Reality's Really Real

I just returned from the inaugural meeting of my Perception and the Mind class. Our professor spent a while discussing the concept of perception, including the more-or-less philosophical puzzle about how or whether we can know whether our perceptions tell us anything objective about the real world. Is there any way, she wondered, to be sure we're not in a Matrix-style virtual reality, where our brain is being fed information to simulate an apparent reality that doesn't exist? Well, no, we can't be certain. But I do think that we have good reasons for thinking that it's exceedingly likely reality is real, and not a virtual computer simulation*, for the very simple reason that making such a simulation would be extremely difficult.

The world around me is tremendously detailed. Just sitting on my bed in my dorm room, using only my (admittedly very strong) glasses as a sensory aide, there's already enough to take in. If I chose to acquire the right apparatus, I could see, in addition to everything that's apparent on inspection, the tiny molecular structures of everything around me, their electromagnetic images outside the narrow visual band, etc. The amount of sheer information about this world that appears to surround me is staggering, in other words. A simulated virtual reality would have to pour that information into me, and would have to generate it, all at once, all using the strength of some computing system. That's hard.

On the other hand, all that needs to happen for this information to be there, and for me to perceive it, on the hypothesis that it is the actual world is just for a world to exist, one that's got lots of detail to it, and for beings within it to develop the ability to detect information about that world. That's not very hard. Or, to be more precise, it is very hard, probably a great deal more unlikely from a properly a priori vantage-point than the task facing the designer of a virtual reality that I described above, but these things are also necessary for the virtual reality. This is something like Carl Sagan's observation that if you wish to make an apple pie from scratch, you must first invent the universe. In order to have a simulated virtual reality, there must be some real world in which that virtual reality is being simulated, and there must be beings within that world who can detect information about it, and therefore be tricked into thinking they've received information about a world that doesn't exist. All of the complexity, the difficulty, the improbability, and the weirdness of the sheer existence of reality and sentient beings within that reality necessary for me to sit here observing such a wonderfully detailed world are also necessary for that world to be a fake. It's just that, if it is a fake, there's a whole extra layer of complexity, difficulty, improbability, and weirdness, entirely added on top of the original layer.

This doesn't mean, of course, that I do have any way of knowing for sure that this dorm room around me isn't a fake. It just means that, if I don't have any direct evidence on the question one way or another, it's staggeringly unlikely to be a fake. It's a reasonable presumption for me to make, in other words, that reality is really real. I might be wrong, and it might even matter a great deal that I'm wrong (though it might not). But until some Morpheus comes along to give me a reason not to do so, I might as well bet on reality, the less-unlikely possibility.



*Of course, the world I see around myself is in a very real sense a virtual computer simulation, in that it's a model constructed by the profoundly complex computer known as my brain of my surroundings, and is not in any way those surroundings themselves.