[AndrewC]

Because close enough is generally good enough for our purposes.

Which is the working definition of determine. In QM you cannot "determine" the future state of the system. For instance, if you "precisely" measure where an electron is, you have absolutely no knowledge of its momentum so you cannot know where it will be.

[LeGrande]

In QM you cannot "determine" the future state of the system. For instance, if you "precisely" measure where an electron is, you have absolutely no knowledge of its momentum so you cannot know where it will be.

We are in perfect agreement then. : )