An optimistic benefit estimate is clearly an overestimate, which is the prediction of Kahneman and behavioral science for project planning. But Hirschman and the Hiding Hand predict the exact opposite, as we saw earlier: underestimated benefits. So it’s a clear-cut case of which of the two opposite predictions is supported by the data. And the verdict comes down overwhelmingly in favor of Kahneman and behavioral science and against Hirschman and the Hiding Hand.
