Moving Beyond the Planning Fallacy: The Emergence of a New Principle of Project Behavior

The question—what explains cost overruns and benefit shortfalls—remains an important conversation in project management. Two theoretical principles, the Planning Fallacy Hiding Hand, shed light on behavior, that is how projects take different complex out-turns. denotes tendency for forecasts of schedules, costs, benefits to be unrealistically close best-case scenarios. however, suggests it not always bad overrate underrate costs difficulties proposed as creativity may help succeed unforeseen ways. This article focuses versus Hand or debate. bone contention whether trumps thus best behavior performance. We unravel ontological, epistemological, theoretical, methodological assumptions behind Then, considering these contrasting uncertainties complexities surround large-scale projects, we xmlns:xlink="http://www.w3.org/1999/xlink">complexify debate line with tradition complexity thinking. In face either/or framing prevails, propose a balanced approach would accommodate both explanations understand why experience shortfalls. so doing, lay foundations emergence new principle— xmlns:xlink="http://www.w3.org/1999/xlink">The Fifth Hand . conclude research agenda highlights key challenges need addressed determine presence Hand.