In the early 1950s, as calculating machines were coming into their own, a few pioneer thinkers began to realise that digital computers could be more than number-crunchers. At that point two opposed visions of what computers could be, each with its correlated research programme, emerged and struggled for recognition. One faction saw computers as a system for manipulating mental symbols; the other, as a medium for modelling the brain. One sought to use computers to instantiate a formal representation of the world; the other, to simulate the interactions of neurons. One took problem solving as its paradigm of intelligence; the other, learning. One utilised logic; the other, statistics. One school was the heir to the rationalist, reductionist tradition in philosophy; the other viewed itself as idealised, holistic neuroscience.