The men who dominated British philosophy from the 1920s to the 1950s all agreed: there is a strict dichotomy between facts and values. The world itself contains only facts, values arise only from our own subjective judgements. But four brilliant women philosophers disagreed. Elizabeth Anscombe, Philippa Foot, Mary Midgley and Iris Murdoch thought the image of the world devoid of value was wrong. They would go on to change the field of moral philosophy forever, writes Benjamin J.B. Lipscomb.

Elizabeth Anscombe, Philippa Foot, Mary Midgley and Iris Murdoch met in Oxford as undergraduates and supported and inspired one another for the rest of their lives. I recently published a book about the interweaving lives and work of this extraordinary quartet of twentieth-century philosophers. When my publisher proposed a subtitle that referenced how they revolutionized ethics, I hesitated. Had these four revolutionized ethics? (Has anyone?)

As I’ve reflected on their achievement, though, I’ve come to think that “revolutionized” is the right word. The four were central actors in an intellectual revolution. Their thought was revolutionary in the sense that Thomas Kuhn explores in The Structure of Scientific Revolutions. Any community of inquirers goes through stretches in which nearly everyone shares the same basic assumptions—the same paradigm. Intellectual progress, in these times, is refinement and problem-solving: tidying up and extending the paradigm. But no paradigm is forever. And when people within a community of inquirers begin highlighting the limitations of a paradigm, and exploring thoughts that won’t fit into it, then you get a revolution. A revolution happened in Anglophone ethics in the second half of the twentieth century, and it was down to these four philosophers.