The Man Who Built The Chess Machine

By Rob Goodman and Jimmy Soni

If anyone has a claim to be considered the founder of the information age, Claude Shannon does. In his groundbreaking work at the intersections of mathematics, engineering, and computer science, Shannon (1916-2001) laid the theoretical groundwork that made modern digital computers possible.

He also inaugurated the field of information theory, inventing the bit—or the objective measure of information—and describing the digital codes that would make it possible for engineers to compress and accurately transmit information. The internet itself rests on the intellectual foundations that Shannon laid.

When we began the research that would turn into the first biography of Shannon, we were impressed to discover the wide range of hobbies and side pursuits he maintained alongside his scientific work—jazz clarinet, unicycling, amateur poetry, and juggling, to name just a few. Like many scientists of his caliber, Shannon loved chess, as well. But we were surprised to learn that, when it came to chess, he was much more than a hobbyist. He was skilled enough to mount a credible challenge to one of the most highly regarded players in the world. That player was Mikhail Botvinnik, the Soviet international grandmaster and three-time world champion.

In the 1950s and ‘60s, the name Claude Shannon had acquired celebrity status in the Soviet Union. Mathematicians in the Soviet Union were early adopters of Shannon’s theories, and translations of his work were widely distributed. All of this would have been impressive on its own—but it’s all the more remarkable given the era. U.S. and Soviet relations couldn’t have been more fraught, and Soviet pride in their technical and mathematical skill meant that they were swallowing no small amount of esteem in expressing their admiration for Shannon’s work. That an American mathematician was so revered caused some minor controversies, but his work was unimpeachable, even to Soviet authorities looking for a reason to call it into question. On the basis of all this, in 1965, Shannon was invited to visit, and he and his wife Betty were off. 

During the course of the trip, Shannon had an audience with Botvinnik. Like Shannon, Botvinnik was trained as an electrical engineer. He began studying the game at age 12—and never stopped. He won game after game, championship after championship, and by the time he met Shannon in 1965, he was a legend within Soviet Russia. Achievement in chess was a point of pride for Soviet leaders, and Botvinnik was among their very best.

Which is all to say that when he met Claude Shannon in 1965 and was challenged to a friendly game by the American mathematician and engineer, he agreed and planned to play it as casually as one of the countless games of show he had had to play for various visiting dignitaries. He nursed a cigarette throughout, his indifference apparent to all in the room. Then, suddenly, Shannon managed to win the favorable exchange of his knight and a pawn for Botvinnik’s rook early in the contest. Botvinnik’s attention was instantly yanked back to the board, and the atmosphere of the room shifted as the Russian champion realized that his challenger was more than just another hapless dignitary.

“Botvinnik was worried,” Shannon’s wife would remember years later. 

The game went on far longer than anyone, including the surprised champion, could have predicted. No record of the game exists, and outside of that early exchange, we know nothing of the specific moves traded between the two. Still, even for Shannon’s early success, there was no real doubt about the outcome. After an astonishing 42 moves, Shannon tipped his king over, conceding the game. Nevertheless, lasting dozens of moves against Botvinnik, considered among the most gifted chess players of all time, earned Shannon lifelong bragging rights.

If Botvinnik was momentarily surprised by his opponent’s resistance, Shannon’s colleagues back in the United States would not have been. In a life of pursuits adopted and discarded with the ebb and flow of Shannon’s promiscuous curiosity, chess remained one of his few lifelong pastimes. One story has it that Shannon played so much chess at Bell Labs that “at least one supervisor became somewhat worried.” As word of his talent spread throughout the Labs, many would try their hand at beating him. “Most of us didn’t play more than once against him,” recalled Brockway McMillan, one of Shannon’s coworkers.

By the time of his match with Botvinnik, Shannon had also given a great deal of thought to chess on a theoretical level. As early as the 1940s, he had begun to turn his curiosity to the question of how and whether a computer might be programmed to compete at chess against a human being.

 In some ways, Shannon’s work on computer chess resembled his far more famous work on information theory: it was another instance of Shannon dropping into a field and, in one stroke, defining its limits and unearthing many of its central possibilities. Decades after the publication of his 1950 paper, “Programming a Computer for Playing Chess,” Byte magazine would put it succinctly: “There have been few new ideas in computer chess since Claude Shannon.”

Chess, Shannon wrote, was not only fascinating it its own right: thinking rigorously about the construction of a chess-playing computer might “act as a wedge in attacking other problems of a similar nature and of greater significance.” Some of those applications, he imagined, could include artificial intelligence programmed for routing phone calls, translating text, or composing melodies. As diverse as these applications were, they had an important quality in common: they didn’t operate according to a “strict, unalterable computing process.” Rather, “solutions of these problems are not merely right or wrong but have a continuous range of ‘quality.’”

In this way, chess was a valuable test case for the emerging generation of artificial intelligence.

Nearly a half century before Deep Blue defeated the world’s human champion, Shannon anticipated the value of chess as a sort of training ground for intelligent machines and their makers.

Shannon believed that, at least within the realm of chess, the inanimate had certain intrinsic advantages. The obvious ones were processing speeds well beyond the human brain and an endless capacity for computation. Further, an artificial intelligence wouldn’t be susceptible to boredom or exhaustion; it could continue to drill into a chess position well after its human counterpart had lost concentration. Computers were, in Shannon’s view, blessed with “freedom from errors,” their only mistakes “due to deficiencies of the program while human players are continually guilty of very simple and obvious blunders.”

This extended to errors of the psyche: computers couldn’t suffer from a case of nerves or overconfidence, two deficits in human players that led to game-ending mistakes (and, in the latter case, would nearly lead Botvinnik to an embarrassing loss). A robot player could play emotionless, egoless chess: a clinical game in which each move was simply a new math problem.

But—and Shannon was emphatic about the “but”—“these must be balanced against the flexibility, imagination and inductive and learning capacities of the human mind.” The great downfall of a chess-playing machine, Shannon thought, was that it couldn’t learn on the fly, a capacity he believed was vital for victory at the elite levels. He cited Reuben Fine, an American chess master, on the misconceptions about top-ranked players and their approach to the game: “Very often people have the idea that masters foresee everything or nearly everything...that everything is mathematically calculated down to the smirk when the queen’s rook pawn queens one move ahead of the opponent’s king’s knight pawn. All this is, of course, pure fantasy. The best course to follow is to note the major consequences for two moves, but try to work out forced variations as they go.”

In mastering the probabilities of each conceivable position, then, a chess computer would not simply be acting as a superpowered grandmaster, but as a fundamentally different kind of player. Essentially, human and computer would be playing two different games while seated across the same board.

So Shannon cautioned against programming computers to behave too much like human beings: “It is not being suggested that we should design the strategy in our own image. Rather it should be matched to the capacities and weaknesses of the computer. The computer is strong in speed and accuracy and weak in analytical ability and recognition.” Computers needed to be taken on their own merits and flaws, not as ersatz humans. What followed in the paper, and what Shannon would later popularize in a less technical article for Scientific American, was the range of strategies that could be programmed into a computer: a blueprint for turning a machine into a good, if not a great, player.

It is an admittedly broad survey: he studied each move’s possible outcomes, considered game-theoretic approaches, outlined how a machine might go about evaluating moves, and concluded that a computer could be programmed to play a perfect game of chess, but that such an outcome would be wildly impractical. This was, in a way, a limitation of the technology of the time: if a contemporary computer’s goal were to calculate all possible moves for itself and its opponent, it would not move its first pawn, Shannon calculated, for 10⁹⁰ years.

For the time being, working chess computers would have to be more limited. But, as he was developing the argument of his chess paper, Shannon was also putting together one of the earliest practical contributions to the field: a chess-playing machine he built himself.

Completed in 1949, the machine was referred to as both Endgame and Caissac (after the fictional “patron goddess of chess,” Caïssa). As the name suggested, Shannon’s machine could only handle endgames, managing no more than six pieces at a time.

More than 150 relay switches were used to calculate a move, processing power that allowed the machine to decide within a respectable 10 to 15 seconds. The relays were concealed in a box decorated with the pattern of a chess board; once they had chosen a move, a series of lights would indicate it to the user.

Simple as it was, it was one of the world’s very first chess-playing computers, a distant ancestor of Deep Blue. It was also an illustration of Shannon’s eagerness to build with his hands what he had dreamed up on paper.

For Shannon, both the chess paper and the chess machine addressed more enticing questions, as well. How should we think about “thinking machines”? Do machines think in the way we do? Do we want them to? What were an artificial brain’s strengths and weaknesses?

Shannon gave a measured answer: “If we regard thinking as a property of external actions rather than internal method, the machine is surely thinking.”

But he would, over time, grow more positive that artificial brains would surpass organic brains. Decades would pass before programmers would build a grandmaster-level chess computer on the foundations that Shannon helped lay, but he was certain that such an outcome was inevitable. The thought that a machine could never exceed its creator was “just foolish logic, wrong and incorrect logic.” He went on: “You can make a thing that is smarter than yourself. Smartness in this game is made partly of time and speed. I can build something which can operate much faster than my neurons.”

There was nothing more mysterious to it: 

I think man is a machine. No, I am not joking, I think man is a machine of a very complex sort, different from a computer, i.e., different in organization. But it could be easily reproduced—it has about 10 billion nerve cells, i.e., 10¹⁰ neurons. And if you model each one of these with electronic equipment it will act like a human brain.

All of this reflection on the theory and practice of chess helped to make Shannon, in 1965, a formidable opponent for a grandmaster. But that wasn’t the only way his Russia trip was a success.

Arriving at his hotel room on the first night of the trip, Shannon complained aloud when he found that the lock on the door was broken. A locksmith instantly appeared—leading him to suspect that the room had been bugged by the Soviet authorities. His next move was to complain aloud that he had never received the royalties for the Russian edition of his published work—and a check materialized the next day.

The writers are the co-authors of A Mind at Play: How Claude Shannon Invented the Information Age.