The most reckless and treacherous of all theorists is he who professes to let facts and figures speak for themselves, who keeps in the background the part he has played, perhaps unconsciously, in selecting and grouping them
—Alfred Marshall, 1885
Understanding that the evidence itself does not contain all the answers is crucial to an informed society. We’re living in a world that along some dimensions feels very data rich. We’re able to collect a lot of data, we have powerful hardware to store and process them, and we have machine-learning techniques to find patterns in them. But many of the important questions we face are about fundamentally dynamic problems. They’re in areas in which, along some dimensions, our knowledge is sparse.
Uncertainty doesn’t mean that you simply cross your arms, close your eyes, and do nothing while you wait for complete certainty.
Many of the people who influence, or want to influence, public policy are reluctant to acknowledge that we’re often working with incomplete information.
Purely evidence-based policy doesn’t exist, Lars Peter Hansen