Friday, April 04, 2003

Common Sense and Inference

Evidence scholarship -- the kind of evidence scholarship conducted by legal scholars, I mean -- has a variety of common presuppositions. Two presuppositions -- or are they canards? -- are very common:

P or C #1: factual inference involves common sense.

P or C #2: common sense involves ineffable intuition.

But now consider this: Douglas Lenat is engaged in an audacious effort to "formalize" and "computerize" common sense knowledge and reasoning.

Is this project not only audacious, but also ... quixotic? Absurd? Bizarre?

Perhaps. But first give the man a break -- and consider the following account in Stanford Magazine (March/April 2002):

To become smarter, the former Stanford professor [Lenat] argues, computers don’t need faster chips or bigger memories. They need an infusion of common sense—all those ordinary facts and assumptions about the world that enable people to survive and communicate with each other. ...

The fruit of his work is Cyc, smart software that according to Lenat knows and applies common sense. Cyc’s schooling has consumed $60 million and 600 person-years of effort from programmers, philosophers and others—collectively known as Cyclists—who have been codifying what Lenat calls “consensus reality” and entering it into a massive database.


No other AI project comes close to Cyc’s scale and ambition, says Nils Nilsson, MS ’56, PhD ’58, an emeritus professor of computer science at Stanford. Though AI researchers acknowledge that the “common sense problem” has to be cracked, most are trying to solve it part by part, he says. “I don’t know that anyone is trying to master all of common sense, apart from Doug.”


After 18 years of painstaking tutorial sessions, Cyc now holds some 1.5 million mostly banal assertions of this kind, all rendered in a formal language developed for the purpose. A few examples:

Water is wet.

Every person has a mother.

When people die, they stay dead.


Will his brainchild live up to its billing? Vaughan Pratt ... expresses doubt. ... [Pratt, an emeritus professor of computer science at Stanford,] ... thinks the problem is Cyc’s premise. Instead of stuffing computers full of knowledge to make intelligent machines, he says, we need to focus on improving their ability to reason and manipulate facts.

Lenat derides this approach as the result of physics envy. He says many AI researchers are consumed with finding the “Maxwell’s equation of human thought”—a simple, elegant formulation that “you could put on a T-shirt and that would unlock the secret of intelligence.” Until that happens, Lenat says, his way is the only way to get a computer to learn common sense.

Is Doug Lenat a post-modern Don Quixote? Or does he hold an important key to intelligence, even human intelligence?

To find out, come to my conference on "inference, culture, and ordinary thinking in dispute resolution" in New York City! Doug will deliver his spiel on Monday, April 28, 2003, at 2:15 p.m. et seq.; and then Henry Prakken, Glenn Shafer, other panelists, and, yes, even you Dear Reader!, will have the chance to question Doug and challenge his views and his audacious bodacious project.

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