If this is true, it is an empirical fact; and you should be able to see the alternative as possible!

Indeed, 2+2=4 is only true in some contexts. For example, sometimes 1+1=1 -- in contexts where separate objects lose their distinct identity as soon as they are grouped. (Think of a particular object several times. How many times did you think of it? But how many objects did you think of?)

Later edit: It is interesting that such a benign comment would get 4 down votes. Perhaps I understand this group well enough to guess why: the experiment I suggested is an entirely "internal" one, it provides no external proof of what I am suggesting. I think that a common reader here feels dismissive of, if not entirely antagonistically towards, knowledge that is internally generated. Personally, I have a preference for the knowledge that arises from internal experience.