Technology / Computers

There's been a resurgence of discomfort with science, bubbling up from both conservative religious quarters and New Age movements. From the times of Galileo through the 1960s or so, the philosophical debate mostly involved God. Something has changed. We've entered a more selfish era, and with it has come a new challenge. The concern with God has been joined by anxiety over the nature of personhood.

In the mid-20th century, scientists like John von Neumann and Alan Turing presented the world with a new framework for explanation. Suddenly, the mind could be interpreted with a technological metaphor: the computer. The phantasmagorical ideas of Freud have since been replaced by crisper notions supported by personal experiences with a ubiquitous gadget. People are simulated in video games, so it's not too hard to imagine real people as components of a higher-resolution video game. One hears a bit of goading in the way some scientists and technologists, including Steven Pinker, Ray Kurzweil, Marvin Minsky, and others, have tried to challenge the notion that individuals are too special to be understood like any other phenomena.

Humility is valuable in science. Even when a scientific idea is true, it can be misused through grandiosity. Your body has a gravitational field, but that doesn't mean that studying physiology can teach you about black holes. It should be uncontroversial to state that the human brain is only partially understood. Certain mental phenomena might be explained and modeled with computers; the most fashionable candidates at the moment envision thoughts competing in the brain like organisms in the wild. But entirely new dynamics may well be needed to explain what brains can do.

The intellectual groundwork for a truce about God was laid down long ago by 18th-century German philosopher Immanuel Kant and many others: Everyone who considers the matter carefully and honestly comes to the conclusion that you can't prove anything about God with science or logic. God is a matter of faith. A great many people, however, believe that consciousness exists—that there's some sort of self or singularity that is the beholder of subjective experience. I must say, I experience myself as being this way. But it seems to me that it's almost impossible to say anything more than that. Saying that subjective experience is an illusion says nothing. Consciousness is precisely the only thing that is just as real if it's an illusion.

In other words, consciousness controversies can be finessed in just the same way as arguments about God. You can't reason about consciousness or perform experiments. It therefore presents another awkward but workable opportunity for cultural compromise—for scientists to stop the goading and for people who care about whether the self is "special" to recognize that there's no threat from science.

To make clear the potential for compromise, and to examine the extent to which we can or can't define consciousness, I offer two dueling thought experiments. The first one has been around a long time. While no one seems to be absolutely sure who told it first, the master teller is unquestionably the philosopher Daniel Dennett, who, not coincidentally, is also one of the staunchest critics of religious belief of our time. Here's how it goes:

Imagine a computer program that can simulate a neuron, or even a network of neurons. (Such programs have existed for years and in fact are getting quite good.) Now imagine a tiny wireless device that can send and receive signals to neurons in the brain. Crude devices a little like this already exist; years ago I helped Joe Rosen, a reconstructive plastic surgeon at Dartmouth Medical School, build one—the "nerve chip," which was an early attempt to route around nerve damage using prosthetics.

To get the thought experiment going, hire a neurosurgeon to open your skull. If that's an inconvenience, swallow a nano-robot that can perform neurosurgery. Replace one nerve in your brain with one of those wireless gadgets. (Even if such gadgets were already perfected, connecting them would not be possible today. The artificial neuron would have to engage all the same synapses—around 7,000 on average—as the biological nerve it replaced.)

Next, the artificial neuron will be connected over a wireless link to a simulation of a neuron in a nearby computer. Every neuron has unique chemical and structural characteristics that must be included in the program. Do the same with your remaining neurons. There are between 100 billion and 200 billion neurons in a human brain, so even at only a second per neuron, this will require tens of thousands of years.