How long have we got before humans are replaced by artificial intelligence?

My view, and that of the majority of my colleagues in AI, is that it'll be at least half a century before we see computers matching humans. Given that various breakthroughs are needed, and it's very hard to predict when breakthroughs will happen, it might even be a century or more. If that's the case, you don't need to lose too much sleep tonight. One reason for believing that machines will get to human-level or even superhuman-level intelligence quickly is the dangerously seductive idea of the technological singularity. This idea can be traced back to a number of people over fifty years ago: John von Neumann, one of the fathers of computing, and the mathematician and Bletchley Park cryptographer IJ Good. More recently, it's an idea that has been popularised by the science-fiction author Vernor Vinge and the futurist Ray Kurzweil.