Should we make Boris Johnson take a Turing test? Now that OpenAI’s ChatGPT has surfaced, we have to question whether we can tell the difference between someone of the former prime minister’s calibre in debate and speech-making and an AI.

ChatGPT was launched amid some big claims, such as the ability to understand and create correct software code and credible reports and articles. But its owners are less certain about  just how good it is at the job – and perhaps more importantly, whether it has the ability to work out when it is doing a bad job. 

It does not take long to work out where the underlying AI, a slightly trimmed version of OpenAI’s GPT-3 in the case of ChatGPT, falls down. Arithmetic is one of the more obvious weak spots. Though large language models can cope with very simple sums – ask one for two-plus-two, and you would expect it to be right – anything that takes a bit more reasoning to calculate will generally trip them up. Much of that...