Probability theory is nothing but common sense reduced to calculation — Pierre-Simon Laplace 1749-1827)
So when you hear we can't forecast the future, or estimates are evil, or we can't know what we need to do until we start doing, focus on the last part of the quote — if you don't apply probability theory and its partner statistics, they are correct and missing that basic common sense. If we apply basic statistically thinking to project management issues, we can calculate the probability of anything. The resulting probability may not have sufficient confidence levels - but we can calculate non the less.
When you hear we can make decisions without estimating the cost, schedule, or capability impacts of those decisions, consider Laplace and the nonsense of that notion. And a recent example of how to do the math for forecast the future behaviour of a project in a specific domain Earned Value Meets Big Data and the annotated briefing of the same paper.
