In his famous 1950 paper titled “Computing Machinery and Intelligence,” Alan Turing explored the question, “Can machines think?”
In this paper he describes an “imitation game” which involves a human interrogator, another human and a digital computer.
The interrogator is placed in a separate room and exchanges messages with the computer and the other human to determine which is which.
Turing suggested that if the interrogator could not reliably identify which was the computer, “one will be able to speak of machines thinking without expecting to be contradicted.”
In his paper, Turing presents arguments refuting several objections that might be raised about whether machines could think, including the “Lady Lovelace objection” cited above.
This imitation game has since become known as the Turing Test, and Turing himself predicted that computers would pass the test by the year 2000.
In recent years, computers have triumphed against opponents in several different spheres.
For instance, in a highly publicized 1997 chess match, an IBM computer called Deep Blue defeated world chess champion Gary Kasparov.
Deep Blue used custom hardware to compute chess moves using a brute-force approach, analyzing hundreds of millions of chess moves per second.
Later, in 2006, Russian chess grand-master Vladimir Kramnik lost in a six-game match against a chess program called Deep Fritz, which ran on personal computer hardware.
In 2011, another IBM computer named Watson competed on the quiz show Jeopardy and defeated the all-time biggest human winner of the show.
At the time of writing, the Turing Test has yet to be reliably won by a computer, but many clever “chatbot” programs have been written to simulate intelligent conversation.