Quarterly notes on civic experimentation.

Campbell's vision.

The psychologist who invented modern policy evaluation — and why his idea of the Experimenting Society is still ahead of its time.

In 1969, a psychologist named Donald T. Campbell published a paper in the American Psychologist titled 'Reforms as Experiments.' It was not a study of any particular policy. It was an argument about what governments should become. Campbell's central claim was this: when a government implements a policy, it is making an implicit prediction — that the policy will improve the outcome it targets. That prediction is testable. It should be tested. And the institutions that implement policies should be designed, from the beginning, to learn from those tests. Campbell called this vision 'the experimenting society.' More than fifty years later, the institutions he imagined are still largely hypothetical. But the tools he developed to make evaluation rigorous — the threats to validity, the quasi-experimental designs, the logic of comparison — are the foundation of every serious policy evaluation conducted today. This is the story of where those ideas came from, what they demand, and why the full vision has proven so difficult to build.