I agree with your main points, but I think it's worth pointing out that even things like 2 + 2 = 4 and X + Y cows in fields A and B, all rest on certain definitions and sets of deductions, many of which go back down to basic axioms which have to be assumed (e.g. for arithmetic, see Peano axioms as an example: https://en.wikipedia.org/wiki/Peano_axioms).
- We have a definition of what a cow is, and we know that cows are discrete/physical objects, and have relatively fixed locations (i.e. that they are not like an electron cloud with a probabilistic location).
- We assume that fields A and B in your hypothetical have clear, non-overlapping boundaries.
- We assume that we are working in a fairly normal universe with a fairly standard model of physics, and that due to the way time works in this universe, a cow cannot simultaneously be located in both fields A and B.
- ...
- (this could get really pedantic and go on forever)
The point is, even the things "we can know with certainty", are only as certain as the framework of observations/deductions/axioms/etc. that they rest upon. Almost nothing is certain on its own, without any further layers of reasoning behind it.
- We have a definition of what a cow is, and we know that cows are discrete/physical objects, and have relatively fixed locations (i.e. that they are not like an electron cloud with a probabilistic location).
- We assume that fields A and B in your hypothetical have clear, non-overlapping boundaries.
- We assume that we are working in a fairly normal universe with a fairly standard model of physics, and that due to the way time works in this universe, a cow cannot simultaneously be located in both fields A and B.
- ...
- (this could get really pedantic and go on forever)
The point is, even the things "we can know with certainty", are only as certain as the framework of observations/deductions/axioms/etc. that they rest upon. Almost nothing is certain on its own, without any further layers of reasoning behind it.