IBM pitted a computer against human debaters in the first public demonstration of artificial intelligence technology it's been working on for more than five years.

The company unveiled its Project Debater in San Francisco on Monday, asking it to make a case for government-subsidised space research. The computer delivered its argument by pulling in evidence from its huge internal repository of newspapers, journals and other sources. It then listened to a professional human debater's counter-argument and spent four minutes rebutting it.