Except, the reason 1+1=2 has to do with how our elementary mathematics systems are setup (the big why questions)---which means that there are possible worlds where 1+1=/=2, but assuming those systems are logically consistent (albeit incomplete---see Godel's Incompleteness Theorem regarding knowledge of a system), there may be other ways to articulate this that would itself be logically consistent and thus translatable. Remember, it's all about defined true premises in a argumentative framework where if the premises are true, then the conclusion must be true.
The joys of maths! =P