DOUGLAS ADAMS, the late lamented author of “The Hitchhiker's Guide to the Galaxy”, dreamed up many comic creations. One of his greatest was the Babel fish. This interstellar ichthyoid neatly disposed of a problem all science-fiction authors have: how to let alien species talk to one another. It did so by acting as a mind-reader that translated thoughts between different races and cultures. Universal communication did not, unfortunately, lead to universal harmony. As Adams put it, “The poor Babel fish has caused more and bloodier wars than anything else in the history of creation.”

For the moment, mind-reading is still science fiction. But that may not be true for much longer. Several lines of inquiry (see article) are converging on the idea that the neurological activity of the brain can be decoded directly, and people's thoughts revealed without being spoken.

Just imagine the potential benefits. Such a development would allow both the fit and the disabled to operate machines merely by choosing what they want those machines to do. It would permit the profoundly handicapped—those paralysed by conditions such as motor-neuron disease and cerebral palsy—to communicate more easily than is now possible even with the text-based speech engines used by the likes of Stephen Hawking. It might unlock the mental prisons of people apparently in comas, who nevertheless show some signs of neural activity. For the able-bodied, it could allow workers to dictate documents silently to computers simply by thinking about what they want to say. The most profound implication, however, is that it would abolish the ability to lie.

Who could object to that? Thou shalt not bear false witness. Tell the truth, and shame the Devil. Transparency, management-speak for honesty, is put forward as the answer to most of today's ills. But the truth of the matter—honestly—is that this would lead to disaster, for lying is at the heart of civilisation.

People are not the only creatures who lie. Species from squids to chimpanzees have been caught doing it from time to time. But only Homo sapiens has turned lying into an art. Call it diplomacy, public relations or simple good manners: lying is one of the things that makes the world go round.

Minds matter

The occasional untruth makes domestic life possible (“Of course your bum doesn't look big in that”), is essential in the office (“Don't worry, everybody's behind you on this one”), and forms a crucial part of parenting (“It didn't matter that you forgot your words and your costume fell off. You were wonderful”). Politics might be more entertaining without lies—“The prime minister has my full support” would be translated as, “If that half-wit persists in this insane course we'll all be out on our ears”—but a party system would be hard to sustain without the semblance of loyalty that dishonesty permits.

The truly scary prospect, however, is the effect mind-reading would have on relations between the state and the individual. In a world in which the authorities could divine people's thoughts, speaking truth to power would no longer be brave: it would be unavoidable.

Information technology already means that physical privacy has become a scarce commodity. Websites track your interests and purchases. Mobile phones give away your location. Video cameras record what you are up to. Lose mental privacy as well, and there really will be nowhere to hide.