The possibility that machines will be able to simulate the human brain is all over the news these days. In the United States, President Obama's Brain Initiative promises $100 million to fund research into "how we think, learn, and remember." In Europe, the Blue Brain Project, headed by Henry Markram, will attempt to recreate the human brain in all of its minute detail so as to engender an artificial mind.
The premise here is that if brains somehow sustain the mind and we deconstruct the brain in detail and we put the information back together in powerful computers, we should be able to recreate consciousness from computer code. Or such is the hope, anyway.
Since the brain integrates external stimuli to give us our experience of reality, would simulated brains be able to recreate reality? And if so, could we be fooled by a simulation, unable to distinguish reality and fantasy?
In his dialogue The Republic, Plato offered the Allegory of the Cave, one of the first meditations on the nature of reality and, more importantly, on how limited our perception of the world is.
The theme has been revisited countless times, for example in the 1999 blockbuster The Matrix. In the 24 centuries separating Plato and Keanu Reeves, we've witnessed the birth of modern science and our growing ability to create mind-bogglingly amazing simulations, virtual allegories that imitate or satirize our world. An obvious question, made famous by Oxford University philosopher Nick Bostrom in 2003, is whether we live in a simulation. And if we do, the next question is, who are the simulators?
In his Allegory, Plato imagined a group of "slaves" chained since birth to a cave. The chained ones could only face forward, toward a wall. Their world was that wall and the images and shadows they could see on it. They were unaware that behind them simulators had made a huge fire and were lifting various objects in front of it. The images and shadows the chained ones saw, their whole reality, were simply projections from these objects. Plato's point was that we are like the chained ones, ignorant of the true nature of reality.
Our senses recreate a small portion of what is out there; only in the pure recesses of the mind, through the power of reason, can we understand the true nature of reality. So, the only perfect circle is the idea of a circle, not the one we draw.
We know that Plato was right, at least in part. Our sensorial perception does give us an incomplete picture of the world, even when amplified by scientific tools such as telescopes and microscopes. Every tool has limits and we can only see as far as it lets us.
I imagine the reader is familiar with the video game The Sims. As the name already says, it is a simulation of reality, where the characters are people doing the things we normally do everyday (well, some activities are pretty weird): go to school, eat, go to the doctor, take care of children and pets, date, etc. Now imagine a hyper-advanced version of the game, where the characters have enough autonomy and ability to self-reflect so as to feel real. Even if, ultimately, the simulators are in control, the characters believe themselves free and independent, responsible for their actions. Clearly, these simulated characters are just a modern version of the chained ones, having the illusion of knowing what their reality is like and, more to the point, having the illusion of personal freedom.
Bostrom suggested something similar, but now we are the chained ones. If simulations continue to grow in sophistication, as they should, we can imagine that, in a not-so-far future, we should be able to create virtual worlds which are practically indistinguishable from the real world, at least as we are able to perceive and measure it. (The simulations would have to grow in detail as we probe deeper into the nature of things, from subatomic particles to the confines of outer space.) We can thus imagine that other intelligent civilizations could be doing the same; or that our descendants are doing it now and we are their game. In this case, we would be nothing but a simulation controlled by the simulators, be they post-human or extraterrestrial.
But here is the thing: if we are truly unable to tell (given that we don't have Keanu Reeves around), does it make a difference if we are a simulation? Does freedom only matter when we are aware that we don't have it?
Note that this is different from having social inequality in the world, with some being freer than others; in the simulation we are all in the same boat, no one freer than any other.
Plato argued that if a chained one had been freed, he would be so terrified that he would quickly run back to the chains and face the wall. He believed, correctly, that only with knowledge can we break the chains and truly ascend to freedom.
We must learn all that we can about the brain, of course. But we must also wonder if there is such a thing as learning too much about how the mind works. Especially if we will have to pay with our freedom.
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