I usually agree with Bill Gates on matters of public policy and admire his emphasis on the combined power of markets and technology. But I think he went seriously astray in a recent interview when he proposed, without apparent irony, a tax on robots to cushion worker dislocation and limit inequality.

The Microsoft co-founder is right about the gravity of the problem and need for action, but he is profoundly misguided in his proposed solution — and in ways that point up problems with the current public debate.

First, I cannot see any logic to singling out robots as job destroyers. What about kiosks that dispense aeroplane boarding passes? Word processing programmes that accelerate the production of documents? Mobile banking technologies? Autonomous vehicles? Vaccines that, by preventing disease, destroy jobs in medicine?