1+1 = a prototype picture of a tie-fighter from Star Wars.

It's also 11, 4, sex, 0 or many other answears depending upon how you look at it.

The choice you make only add's to the complexity when you try to explain your version of the 1+1 event in a way that others will understand.

The original metaphor, of 1 + 1 = 3, was by Edward Tufte. I find it apt