1+1=2 proof

Machine-translated from the German article

1 + 1 = 2 is a mathematical equation that often stands in for a trivial statement. In the philosophy of mathematics and epistemology, such arithmetic formulas are often cited as an example of a statement that is either obvious or only appears obvious and requires a deeper justification. Immanuel Kant counts the formula 7 + 5 = 12 among the synthetic judgments a priori, that is, a judgment made without a basis in experience (a priori) which is true on the basis of the decomposition of the individual concepts.