Since we cannot interact with the system, without disturbing the system at very small scales, all we can do is compute the probabilities of how the system will behave when we do interact with it.
It’s just like saying, we cannot predict w/o extreme computation the result of a flipped coin – heads or tails. All we can do is postulate the probability of the same. (assume this to be equivalent to our inability to interact with a system without disturbing it, how a system will behave and evolve after interaction).
This is exactly what we would expect, at the smallest of scales. [Plank Scales]