A former colleague of mine—not the philosopher interested in tosspots, but an American historian—liked to search for words or expressions having two, diametrically opposed meanings.  These are sometimes called “Janus terms,” because like the Roman god of beginnings they face in two directions simultaneously.  An example would be the verb “table,” which in meetings held in the US means “shelve,” “postpone discussion on,” and in British meetings “put on the agenda for immediate discussion,” “bring up.”  “Cleave” means both “split asunder” and “cling to.” 

As for my colleague’s collection, he told me once that its jewel was “I felt a perfect ass.”  This might be spoken by someone making a sexual appraisal, or alternatively by an altogether less virile type, an English, Bertie-Woosterish figure confessing his embarrassment at some social contretemps.  My colleague might have found this two-ways-facing phrase in a book by the English novelist Kingsley Amis or in a story by the American Peter DeVries.  As an addition to his collection I suggested the famous response given by an established writer to an aspirant who has sent him a manuscript: “Thank you for your book.  I will lose no time in reading it.”  Over the years this nicely equivocal phrase, on the one hand polite and encouraging, on the other frankly dismissive, has been attributed to William Cullen Bryant, Disraeli, and Evelyn Waugh.  Perhaps they all used it, copying from each other.

At least one radically ambiguous phrase, when spoken aloud, had very serious consequences.  In 1952 two teenage English delinquents tried to rob a warehouse in Croydon, south London.  One, the sixteen-year-old Chris Craig, was armed.  The other, a developmentally challenged, slightly older youth named Derek Bentley, was not.  The two were spotted and the police came to investigate.  At one point during the subsequent confrontation on the roof of the warehouse, as the police officers were closing in and demanding the weapon be given up, Bentley said to Craig “Let him have it, Chris!”  By this, he might have meant “let the copper have your gun,” “give up.”  Equally, he might have meant “fire away,” “shoot him”—the standard meaning of the four words in American film noirs or cop shows on television. 

In the event, Craig did start firing his gun, eventually killing a police sergeant.  At the subsequent trial, the meaning of the words became the key legal issue, and eventually the court chose to believe they bore the “fire away” meaning.  As a juvenile, Craig received a relatively light sentence, but Bentley, convicted of having incited murder, was hanged.  Miscarriage of justice?   For a treatment of the story on film, see the British action-and-courtroom drama from 1991, Let Him Have It, with a superlative cast directed by Peter Medak.  Here’s the key sequence:

Does it matter what Janus language means?  Ask Derek Bentley’s family.