The problem is that people try to eliminate uncertainty instead of trying to manage it effectively. If you're trying to make estimates with more than order-of-

The problem is that people try to eliminate uncertainty instead of trying to manage it effectively. If you're trying to make estimates with more than order-of-magnitude precision, then you're probably doing something wrong. If we drove cars like we develop software, we would pre-calculate a list of instructions, set a timer, and then execute those instructions without regard to what's actually happening on the road. With practice, you could probably get better at making those lists of instructions, but why bother? The general approach is just ridiculous. Decades of experience have shown that there is enough inherent uncertainty in software development that trying to plan everything from the start just doesn't have a high success rate. Even if you know everything that has to be done today to get the job done, your environment will change, and your stakeholders will change their minds. What good is software that perfectly solves the problem you had two years ago? Once you dig through all of the buzzwords, "Agile software development" is simply about applying closed-loop control theory to software development: You structure your project to provide high visibility and to allow frequent changes in direction, then you iterate and make adjustments until the result is satisfactory. Everything else generates unnecessary risks that somebody ends up paying for.