Question: What exactly is 2+2?
The answer depends:
For a neo-hilbertian-formalist it would be the product of re-writing the string of signs according to axiomatic rules.
For a solipsistic intuitionist the product of a mental construction.
For a die-hard-empricist the average result obtained by a sufficient number of trials by all means possible (notches on a stick, calculator, test-persons, etc.).
For early Husserl a collection of the two sub-collections (or sums) of multiplicities of unities, which in their abstraction are all identical to themselves (and only to themselves) and different from all others.
For a Fregean an element of an extra-mental ideal set of the sums of all couples.
I can go on a while I think ...
(Notice: I am being quite serious about this.
)
However they would all agree to the answer being 4, but vastly disagree on what that would mean, what it would
be and how we obtained the result.