One axiom of rationality is to ground current decisions on later outcomes (termed "prospection").The planning fallacy, in contrast, occurs when intuitive reasoning misjudges the future and leads to schedule conflicts, cost overruns, hasty course corrections, missed deadlines, or other regrets. 1 Stunning examples of the planning fallacy occur when sincere political leaders promise large infrastructure projects yet fail to deliver on time and within budget. Mundane examples of the