Fifteen years after Grand Master Garry Kasparov lost to an IBM supercomputer known as Deep Blue, one of its designers has revealed that the move was the result of a bug in its software.

The revelation was published in a book by statistician and New York Times journalist Nate Silver titled ‘The Signal and the Noise’ — and promptly highlighted by Ezra Klein of the Washington Post.

For his book, Silver interviewed Murray Campbell, one of the three IBM computer scientists who designed Deep Blue, and told him that the machine was unable to select a move and simply picked one at random.

At the time, Deep Blue versus Kasparov was hailed as a seminal moment in the history of computer science — and lamented as a humiliating defeat for the human intellect. But it may have just been a lesson that as humans, we tend to blow things way out of proportion.

Many chess masters have long claimed that Kasparov was at a significant disadvantage during the match.

Deep Blue’s designers had the opportunity to tweak Deep Blue’s programming between matches to adapt to Kasparov’s style and strategy.

They also had access to the full history of his previous public matches.

Kasparov had no similar record of Big Blue’s performance.

Because the machine had been heavily modified since he had last played it, he was essentially going in blind.

That strange move was chalked up to these advantages.

The IBM team did tweak the algorithms between games, but part of what they were doing was fixing the bug that resulted in that unexpected move.

The machine made a mistake, then they made sure it wouldn’t do it again.

The irony is that the move had messed with Kasporav’s mind, and there was no one to fix this bug.

“Kasparov had concluded that the counterintuitive play must be a sign of superior intelligence,” Campbell told Silver.

“He had never considered that it was simply a bug,” he said.