In a so-called knowledge society, whenever we have to choose, decide, anticipate, or entrust a task, the range of options available tends to be so large that we cannot be satisfied that no relevant possibilities have been overlooked. Both individuals and societies as a whole are compelled to manage this explosion of opportunities in its myriad forms, which is why the astute management of the excess of options occupies the majority of their time. Our most important act is the organization of uncertainty. Given the lack of proportion between our limited knowledge and the problems we need to confront, what we celebrate as a “knowledge society” is also a society of ignorance. This essay, published as a guest column, concludes that, in the coming years, the principal controversies we will face will involve questions about what we know, about what we do not know, and about the incompleteness of the knowledge on which we must base collective decisions.