>>41Because the accepted axioms applied to the real numbers concludes so. In Peano arithmetic, from which basic arithmetic gets it's theoretical underpinnings (which is itself derived from numer theory, set theory, and logic), the existence of a successor function, which returns the immediate value that proceeds the given value in the set of natural numbers, is presumed. The addition operator in the form of
a+b
is taken to mean that the successor of
a
is composed
b
times. With
1+1
, the successor function is applied once to
1
, which results in the immeditate successor, which is
2
. Once this is derived from the natural numbers, it can be trivially extended to many other fields, such as
C.
I hope that this has enlightened you a bit!