PERSON
Michael Dummett
The Oxford logician who spent sixty years asking what it is to understand a language—and whose answers, built for human beings, have become the sharpest available instrument for locating precisely what a fluent machine has and what it irrevocably lacks.
Sir Michael Dummett died in 2011, fourteen years before a chatbot could hold a conversation indistinguishable to most observers from one with an educated adult—and he is, against all expectation, the philosopher whose tools cut deepest into what such a machine is. He never wrote a word about artificial intelligence. His life's work ran through Gottlob Frege, the foundations of logic, intuitionistic mathematics, the reform of voting systems, the history of tarot, and a long fierce campaign against British racism. Yet no thinker of the twentieth century pressed harder on the single question that the existence of fluent machines now forces upon us: what is it to understand a language, and how would you ever know that something does? Dummett refused to let understanding be a mystery hidden inside a skull. He insisted instead, following a line from the later
Wittgenstein reconstructed with far more system than Wittgenstein ever offered, that to understand an expression is