think than on devising formulas to organize, store and probe data. What had begun as a problem of “artificial intelligence” became, in the end, a puzzle of mathematics. The mystery of human thought, that great unknowable sea of chemicals and instinct and experience that would have let you place your finger on just the song to open the heart of your date, had been unlocked by data. Here was the “Disappearing Al Problem.” A puzzle that looked like it needed computer intelligence demanded, in the end, merely math. The AI had disappeared. For several decades this accidental digital magic trick - “Hey, where'd the AI go?!” - bedeviled machine intelligence. It gave the entire thinking machines enterprise a bit of an occultish flavor. Many problems that once seemed to demand the miracle of thought really only needed data. The human was still doing the thinking; the computer was simply computing. It was extremely easy to draw a line between where the human ended and the machine began. This was a puzzle that had been, in a sense, anticipated at the very dawn of the digital revolution by the mathematician Alan Turing in a 1950 paper called “Computing Machinery and Intelligence” that he published in the British journal Mind. “Can machines think?” Turing began.?5” His idea was to test this question in the following way: Have a research subject - a secretary, a graduate student, anyone - chat with an invisible interlocutor by way of a keyboard. Then ask: What are you connected to? Another human? A machine? Turing figured you could call a machine “artificially intelligent” if it could fool a user into thinking it was human. “Please write me a sonnet on the subject of the Forth Bridge,” Turing suggested a tricky user might ask. What computer could possibly know about this famous Scottish landmark; to say nothing of being able to rhyme “Forth”? When the response came back, “Count me out. 1 could never write poetry,” you'd think that sounded awfully human. “Add 34957 to 70764,” Turi