It may not be on the level of the Montagues and the Capulets, or the Sharks and the Jets, but in the world of geeks the rivalry is about as intense as it gets. For decades, two competing “tribes” of artificial intelligence experts have been furiously duelling with each other in research labs and conference halls around the world. But rather than swords or switchblades, they have wielded nothing more threatening than mathematical models and computer code.

On one side, the “connectionist” tribe believes that computers can learn behaviour in the same way as humans do, by processing a vast array of interconnected calculations. On the other, the “symbolists” argue that machines can only follow discrete rules. The machine’s instructions are contained in specific symbols, such as digits and letters.

After an initial burst of enthusiasm for connectionist thinking among AI pioneers, the symbolist tribe came to dominate as researchers realised that human and machine intelligence are very different attributes. But over the past decade the maverick connectionists have had their revenge, making many of the most striking advances in AI, such as speech and image recognition systems, conversational chatbots, semi-autonomous cars and the AlphaGo program that famously beat the world’s strongest champion in the fiendishly complex game of Go in 2016.