IN 2014 Andrew McAfee and Erik Brynjolfsson of the Massachusetts Institute of Technology published "The Second Machine Age". The book was a balanced portrait of how new digital technologies were poised to improve society, even as they increased unemployment and depressed wages. In their latest work, "Machine, Platform, Crowd", the authors seek to explain the business implications behind these developments. Mr McAfee and Mr Brynjolfsson believe that the latest phase of computers and the internet have created three shifts in how work happens. The first is artificial intelligence (AI): a move from man to machine.

Over the past few years we've developed artificially intelligent machines that can do many things that used to require human minds: understanding speech, diagnosing disease, checking the terms of a contract, designing a mechanical part from scratch, even coming up with new scientific hypotheses that are supported by subsequent research. As this new software is embedded in hardware we'll get self-driving cars, trucks, and combines; delivery and inspection drones; and robots of many kinds. These technologies are improving more quickly than even their creators would have predicted at the start of the decade, and the fact that the world's best players of both the Asian strategy game go and no limit heads up Texas hold-em poker are now AI systems indicates just how deeply they're encroaching into human territory. So shouldn't we be preparing ourselves for massive AI-induced technological unemployment? A widely cited 2015 analysis by Carl Frey and Michael Osborne of Oxford University found that 47% of current jobs in the US were susceptible to computerization.

That advice, quoted in Machine, Platform, Crowd, is well followed by Andrew McAfee and Erik Brynjolfsson in their latest business book, which tries to make sense of the "technology surge" that is bewildering so many executives. The two academic authors from Massachusetts Institute of Technology, who became the pin-up boys of the Davos crowd for their previous book on The Second Machine Age (2014), do a neat job of scanning the technological horizon and highlighting significant landmarks. This is a clear and crisply written account of machine intelligence, big data and the sharing economy. But McAfee and Brynjolfsson also wisely acknowledge the limitations of their futurology and avoid over-simplification. No one can really have much idea how the business world is going to evolve or predict the precise interplay between all these fast-changing forces.