The venue: the British Library, the world's largest library with around 14 million books. The event: the Reith LecturesAn annual series of four lectures, broadcast over the radio and freely available to everyone. It is named after one of the founders of the BBC, John Reith., a radio lecture series delivered every year by one of the world's leading lights. The speaker: computer scientist Stuart RussellA British computer scientist who is best known for his contributions to thinking on AI., a renowned expert on artificial intelligence. It all added up to an explosive warning about the future of AI.

Russell told his audience that existing machine intelligence cannot surpass human intelligence, while machines can be trained to do better than human beings at specific tasks, they cannot use their intelligence for a variety of functions.

For example, search engines have much better memories than human beings, but no capacity for planning. Other AIs can make brilliant plans, but have no memory. Humans have both memory and planning, as well as a number of abilities like logical processing and speech recognition. In other words: "machines do not have an IQA means of measuring human intelligence. A person's IQ is usually ascertained by making them sit a standardised test. Some have criticised these tests as a means of evaluating intelligence, claiming that they ignore much of what it means to be intelligent.".

Because we cannot measure the general intelligence of machines, we define intelligence as the ability to carry out actions to achieve goals. If an AI that is built to win chess games can beat a grandmasterA title awarded to the world's very best chess players., it is an intelligent AI.

But the holy grailSomething that is eagerly sought after. The real holy grail was the cup that Jesus used at the Last Supper, for which Christians searched fruitlessly for centuries. of computer scientists has always been to create artificial general intelligence (AGI): a general-purpose AI that can learn how to do any task, and perform it much more effectively than humans can.

The implications of this are huge. Today, to keep society running, we need a complex network of specialists in a variety of fields. Constructing a building, for example, requires architects, engineers, lawyers and hoards of other workers with specific skills and tasks. But an AGI would have access to all human knowledge and skills. A single programme could carry out every one of these functions. Most human labour could become unnecessary.

The problem is, whether the AI has a specific purpose or many purposes, its intelligence is still measured in the same way: its ability to carry out its aims. That means unlike human intelligence, it is not limited by moral considerations or respect for human life and dignity in its pursuit of these aims.

And whereas an AI that is just built to win chess games cannot do much harm, a super-powerful AGI could do untold damage. Imagine a superintelligent AGI that is designed to make money on the stock market by analysing which companies are likely to be successful and buying shares in them. It might reason that the best way of doing this would be to invest in arms companies - and then start a world war.

And if someone chose to weaponise AGI, they could gain enormous power. Scientists have warned of swarms of tiny armed robots using facial recognition software to identify and assassinate specific targets.

AGI might not be too far off: 40 organisations worldwide are actively researching it. Russell thinks we need safeguards to ensure that AGI works to the benefit of humanity.

Yes, say some. In our haste to produce intelligent machines we have forgotten what intelligence really is. What makes humans smart is not just that we can work to achieve our aims: it is our moral reasoning, our ability to decide that some actions are wrong. We need to teach AI how to think morally.

No, say others. No AGI will ever develop that is capable of outsmarting the whole of humanity. Naysaying and doom-mongering from people like Stuart Russell is just preventing us from producing AI that could revolutionise the lives of billions of people around the globe.