This article brings to light how AI research has benefited from post-Wittgensteinian philosophy. My research shows that Wittgenstein’s work began to engage the attention of AI researchers not only in the 1970s down to the present but right from the early beginnings of computational research in the 1950s. More specifically, his later philosophy inspired a group of researchers called the Cambridge Language Research Unit (CLRU) to start one of the first programs in machine translation, information retrieval, mechanical abstracting, and knowledge (...) representation technologies in the early 1950s, all of which have later been claimed for AI and cognitive science. I focus on the philosophical work of CLRU founder Margaret Masterman and her extraordinary but forgotten contributions to ordinary language philosophy. (shrink)