However, according to historian Stephen Stigler, the second benefit was really Fisher’s main reason for advocating randomization. He was the world’s master of quantifying uncertainty, having developed many new mathematical procedures for doing so. By comparison, his understanding of deconfounding was purely intuitive, for he lacked a mathematical notation for articulating what he sought. Now, ninety years later, we can use the do-operator to fill in what Fisher wanted to but couldn’t ask. Let’s see, from a causal point of view, how randomization enables us to ask the genie the right question.
