Having relatively recently written a book on game theory, I have given quite a lot of thought to the nature of games, and from that I'd say that chess has two significant weaknesses compared with backgammon. One is the lack of randomness. Because backgammon includes the roll of the dice, it introduces a random factor into the play. Of course, a game that is totally random provides very little enjoyment. Tossing a coin isn't at all entertaining. But the clever thing about backgammon is that the randomness is contributory without dominating - there is still plenty of room for skill (apart from very flukey dice throws, I can always be beaten by a really good backgammon player), but the introduction of a random factor makes it more life-like, with more of a sense of suspense.
Chess is wonderfully cerebral, but it lacks any parallel with real life, where luck always plays a significant part. By mixing strategy and luck, backgammon is far more visceral. And this aspect is made even stronger by backgammon’s other strength - it has a gambling element.
This doesn't mean that backgammon has to be about money (and of course you can bet on a game of chess just as much as you can backgammon) - it’s the incorporation of a type of gamble into the play itself. Backgammon has the concept of doubling. At any point, a player can challenge their opponent to make a better forecast on the outcome of the game, gambling on that by accepting a double. If the opponent accepts, the value of the game is doubled, but if the opponent refuses, they immediately lose. If you play backgammon without doubling, you miss a major part of its gameplay attraction.
The originator of game theory, John von Neumann, famously told British mathematician Jacob Bronowski 'Chess is not a game. Chess is a well-defined form of computation. You may not be able to work out the answers, but in theory there must be a solution, a right procedure in any position. Now real games are not like that. Real life is not like that. Real life consists of bluffing, of little tactics of deception, of asking yourself what is the other man going to think I mean to do.' While I think von Neumann was a little hard on chess, and I personally extend the definition of games to include it, for me the combination of a random element and the forecast challenge of doubling makes backgammon the superior game.
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