The Smarter You Are, The Stupider You Are : 13.7: Cosmos And Culture : NPR: Our values and biases are expressions of who we are. It isn't so much that our prior commitments disable our ability to reason; it is that we need to appreciate that reasoning takes place, for the most part, in settings in which we are not neutral bystanders.
It shouldn't be surprising that smart people who care about an issue will use their wits to fight for their values. This can be a corrupting influence, it can lead you to fill in the wrong bubble, but it need not be.
This is where the real aims of education come in.