Edge in the News: 2007

Daniel C. Dennett, a philosopher and cognitive scientist at Tufts University who has written extensively about free will, said that “when we consider whether free will is an illusion or reality, we are looking into an abyss. What seems to confront us is a plunge into nihilism and despair.”...

A vote in favor of free will comes from some physicists, who say it is a prerequisite for inventing theories and planning experiments.

That is especially true when it comes to quantum mechanics, the strange paradoxical theory that ascribes a microscopic randomness to the foundation of reality. Anton Zeilinger, a quantum physicist at the University of Vienna, said recently that quantum randomness was “not a proof, just a hint, telling us we have free will.” ...

If by free will we mean the ability to choose, even a simple laptop computer has some kind of free will, said Seth Lloyd, an expert on quantum computing and professor of mechanical engineering at the Massachusetts Institute of Technology.

Every time you click on an icon, he explained, the computer’s operating system decides how to allocate memory space, based on some deterministic instructions. But, Dr. Lloyd said, “If I ask how long will it take to boot up five minutes from now, the operating system will say ‘I don’t know, wait and see, and I’ll make decisions and let you know.’ ”

Why can’t computers say what they’re going to do? In 1930, the Austrian philosopher Kurt Gödel proved that in any formal system of logic, which includes mathematics and a kind of idealized computer called a Turing machine, there are statements that cannot be proven either true or false. Among them are self-referential statements like the famous paradox stated by the Cretan philosopher Epimenides, who said that all Cretans are liars: if he is telling the truth, then, as a Cretan, he is lying.

One implication is that no system can contain a complete representation of itself, or as Janna Levin, a cosmologist at Barnard College of Columbia University and author of the 2006 novel about Gödel, “A Madman Dreams of Turing Machines,” said: “Gödel says you can’t program intelligence as complex as yourself. But you can let it evolve. A complex machine would still suffer from the illusion of free will.”