remnants of remnants

The more people who find out that I’m working on an MA at Leeds, the more I’ve realised that I really need to solve a pressing problem. The problem is that I don’t know what to say when they ask, “Oh really? What area do you work on?”.

I’m not saying I don’t know what area. I’m 8000 words into a 15,000-word dissertation, so I have a pretty good idea. The problem is what to say.

Specifically, I don’t have a way to explain the problem without pissing people off. So far I’ve come up with three possible replies. The first one is vacuous and irritating; the second makes me sound completely bonkers; and the third makes my subject sound tedious and pointless.

After much consideration, I think the reason I have this difficulty is that my subject is, in fact, vacuous and irritating and bonkers and tedious and pointless. I knew it was bad when I met a York philosopher — a philosopher, mind you — and he asked what I was working on. I explained it as best I could, and the poor chap’s incredulous response was, “Really? And is that taken seriously?”. Come to think of it, that was also my MA supervisor’s response when I first outlined my subject to him.

But recognising that fact hasn’t helped me to find a good answer to the question. So I’m going to try and iron one out here, in the hope that I can avoid the whole conversation in future simply by pointing people to this blog entry. (Yes, I’m serious.)

Here are my three candidate answers to the question “What are you working on?”.

The vacuous answer

Philosophy. Now let’s change the subject.

The bonkers answer

Basically I’m looking at whether we have reason to believe that we’re actually computer-simulated people living in a computer-simulated world, run by a technologically very advanced species that developed from something like ourselves, rather than real people in a real world as we usually assume we are.

After giving this answer, I usually feel the need to add that I am actually a useful member of society in other ways, for instance by writing about science research and by training choirs. And I’m self-funding, so bog off.

The tedious and pointless answer

All right. Take a deep breath here.

You’ve heard of philosophical skepticism, right? This is the worry that it’s possible that the world as we see it doesn’t actually exist. Think of something like the Matrix, for instance. You might (says Hilary Putnam) actually be a disembodied brain floating in a vat on Mars, being fed computer impulses to make you think that you’re sitting at your computer on Earth, reading these words. Or you might (says Descartes) be constantly deceived by a malicious demon into believing that the world is the way it looks. Or you might (says Chung Tzu) be a butterfly dreaming that you’re a man.

OK, sure, these are silly science-fiction theories, and no, there aren’t any serious philosophers who actually believe them. But the interesting thing is that they’re not impossible — and this is why they’ve have fascinated philosophers for literally thousands of years. You can’t rule them out, it seems. Think about it: everything would look exactly the same to you whether you were a brain in a Martian vat or a human on Earth.

And this causes an interesting complication in our everyday lives. We think we know stuff. For instance, I think I know that I live in York and I’m hungry right now. If I know anything at all, I know these things. But of course, if I’m a brain in a vat, I don’t live in York and I’m not hungry right now; I simply believe these things, and wrongly. And since I just admitted that it’s possible (although highly unlikely) that I’m a brain in a vat, it’s therefore possible that I’m wrong about my beliefs that I live in York and I’m hungry right now. And if it’s possible that I’m wrong about these things, then I can’t be said to know them (assuming knowing involves being sure). Therefore, nearly everything I think I know, I actually don’t. In fact I know hardly anything!

So much for skepticism. Like I said, it’s not that philosophers actually believe it. It’s just that they worry that they can’t rule it out, and this in itself has serious consequences for what we normally think of as ‘knowledge’.

Anyway, what I’m working on isn’t actually skepticism. It’s a new argument which takes the traditional skeptical argument one step further, which says not just that the scenario is possible, but that it’s likely. It’s called the simulation argument, and here it is:

Look at our society. Good empirical evidence suggests that if we manage not to go extinct in the next couple of centuries, our technological abilities will progress to the point where our descendants will be able to run incredibly complex computer programs using a trivial fraction of our total computing power. These programs could include simulations of our descendants’ ancestors, namely us. So suppose our twenty-fifth century descendants decide to create a simulation of twenty-first century Earth, populated by simulated people like us (for historical research, entertainment, whatever). If this ancestor-simulation is detailed enough, the simulated people inside it will be conscious and they will believe themselves to be living in the real world.

The punchline: If all this is true, then what makes you think you aren’t living in an ancestor-simulation run by a future society?

Crunch some numbers. Suppose our descendants create five complete, detailed ancestor-simulations (using a trivially tiny percentage of their computing power). Each one includes six billion simulated people, because there were six billion real people on twenty-first century Earth, which is what they choose to simulate. So across all times, the universe contains six billion real twenty-first-century people and thirty billion simulated ones. (With me so far?) And all of those people believe themselves to be living in the real world, but as it turns out, 5/6 of them are wrong.

In other words, if our descendants create just five ancestor-simulations, the chance that you live in a simulation is 5/6, or 0.833. And what if they create ten, or fifty, or a thousand such simulations? And what if the people in those simulations create their own simulations, each containing loads of second-level simulated people?

Don’t get me wrong, there are some weak points in the argument. Maybe you think that simulated people inside computers will never be conscious, no matter how complex their little sim-brains. Maybe you think that societies like ours are likely to go extinct before they get to the point of creating simulations. These are all issues to discuss and debate. And that’s what I’m working on for my dissertation.

There. Aren’t you glad you asked?