By definition any perfect knowledge of the future is impossible. Regardless of why. That's a trite observation. What matters is than an estimate can be made be

By definition any perfect knowledge of the future is impossible. Regardless of why. That's a trite observation. What matters is than an estimate can be made better than not estimating at all. It's funny how all these problems come up in other disciplines, but they don't throw their hands in the air and quit. They accept that the Nirvana Fallacy is not an acceptable reason to not estimate and they go ahead and do it anyway.