Yes indeed, many of these are arbitrary pairs - some of them are entirely debateable - good/evil for instance. And I think Jeb is onto something with that "people want simple choices" thing, but What I wonder is do they tend towards YES/NO choices due to the bilateral symmetry within their bodies? I wonder how much the shape of our brains and bodies affects the way we conceptualize. I bet its a lot more than most people would think about on a daily basis.