Ok, but what about philosophical positions that CAN be defended? For example, your statement is a philosophical position in itself, no? A position, I assume, you believe to be "defensible?"
Through defensible positions even if we ultimately believe the conclusion is wrong we learn new ways to reason about life and the world around us. New tools to inform our interaction with the world or at least new thought processes to communicate with our fellow humans.
The bald statement that 2+2 = 17 or even that 2+2=4 is worth nothing if you can't explain why you think its correct.