Reasonableness - More Value-Based Than Fact-Based

We have no scientific way to measure how reasonable something is, so even though it sounds strange, we must conclude that reasonableness is more rooted in value than in fact.  Sometimes I think reasonableness is a preference for facts, but even a preference for facts would be considered a value and not a fact itself.

Why do people prefer logic to emotion?  Probably because it's closer to truth.  But why do they like truth?  Probably for an emotional reason.