Notice that mathematicians don't take real numbers for granted too - we need to assume their existence first. Looking at this, complex numbers stop being that a

Notice that mathematicians don't take real numbers for granted too - we need to assume their existence first. Looking at this, complex numbers stop being that arbitrary, just another extension of reals. Also, it's nitpicking, but i is imaginary, not irrational. Also, complex numbers were accepted by mathematicians before negative numbers (it's something that boggles minds of some people).