Anyone who fears that we may be wiped out by artificial intelligence should just buy a robot vacuum cleaner and watch the unshakable determination with which it returns, over and over again, to the one corner of the room where it gets stuck every time.

A realistic “Terminator" movie would consist of two hours of well-meaning humans patiently disentangling the T-800 from the rug or dragging it out from under the bookshelf while it beeps pathetically for assistance.