New Delhi, June 10 -- When in 2019 OpenAI finished training a new large language model called GPT-2, the artificial-intelligence lab initially declared it too dangerous to be released. Dario Amodei, then OpenAI's research director, insisted that the world needed time to prepare.

In the end, it was released later that year. A sequence of far more powerful models have since been developed without unleashing Armageddon. Yet seven years on, Mr Amodei, now the head of OpenAI's bitter rival, Anthropic, is worried once again. On April 7th he declared that the latest addition to his lab's Claude family of models, dubbed "Mythos", is too powerful to be made widely available just yet. This time, he might be right.

According to Anthropic, the capa...