There is intrinsic uncertainty in product development. Uncertainty is often confused with risk, where unknowns can be identified in advance. Traditional predictive project management methods are based on risk management and it will be explained why these methods often are less effective in domains with higher uncertainty. Adaptive methods seem to be more effective, as they better deal with that uncertainty. Examples will be given where adaptive methods have led to higher predictability. But many managers still often believe predictive methods lead to higher predictability. We will formulate some hypotheses on why managers still prefer predictive methods, based on own experience and initial research. Further research is required to validate these hypotheses.