I find the phrase β€œnot an exact science” interesting. We all use it and it probably has its roots back to the days when we all thought science was exact. These days, science (even Maths?) seems to be more of an ongoing and emerging suite of hypotheses that we keep refining.

I don’t expect the phrase to change anytime soon, so I guess we can file it away with the ever-increasing number of idioms (is that the right word?) in our day-to-day language usage.