Cox-Forbes Theory

The Cox-Forbes theory is a long-debunked theory on the evolution of chess put forward by Captain Hiram Cox (died 1799) and extended by Professor Duncan Forbes (1798–1868).

The theory states that a four-handed dice-chess game (Chaturaji) was originated in India in approximately 3000 BC; and that arising from the results of certain rules, or the difficulty in getting enough players, the game evolved into a two-handed game (Chaturanga). On account of religious and legal objections in Hinduism to gambling, the dice were dropped from the game, making it a game purely of skill.

In Forbes' explanation, he calls the four-handed dice version Chaturanga and insists that Chaturaji is a misnomer that actually refers to a victory condition in the game akin to checkmate. In his 1860 account, the players in opposite corners are allies against the other team of two players. He represents this "Chaturanga" as gradually developing into the two-player diceless form by the time it was adopted by the Persians as "Chatrang". He further asserts that this name later became "Shatranj" after the Arabic pronunciation.

The theory was allegedly based on evidence in the Indian text Bhavishya Purana, but more recent study of the work has shown the evidence to be weaker than previously thought. The earliest Puranas are now assigned a more conservative date of 500 BC, rather than 3000 BC. As a result, the theory is now rejected by all serious chess historians.

Albrecht Weber (1825–1901) and Dutch chess historian Antonius van der Linde (1833–1897) found that the Purana quoted by Forbes did not even contain the references he claimed. While working on Geschichte und Litteratur des Schachspiels (Berlin, 1874, two vols.), Van der Linde also found that the actual text around which Forbes had built his entire theory (Tithitattva of Raghunandana) was actually from around AD 1500, rather than 3000 BC as claimed by Forbes. Van der Linde thought that Forbes deliberately lied, and was furious. John Griswold White wrote in 1898, "He did not even make good use of the material known to him." (Hooper & Whyld 1992, pp. 143, 226–7)