If we are going to have any success at things like raising the sanity waterline, we need to understand how and when human reasoning fails. And we need to appreciate how much that depends on circumstances. In the same way that almost any of us if we were born in the US in 1810 would have been in favor of slavery, and almost any of us born in 1930 would have been against interracial marriage, it is important to understand that we don't have some magic gift of rationality. If one of us were in the same situation as the Kerchers, we'd likely react the same way, and I'd go so far as to say that even someone as highly rational as most LWians with all the experience and awareness of cognitive biases would still likely react the same way.

To destroy bias we must understand it.

There really was a time when I considered self deception a worthwhile excuse for subsequent bad behavior rather than just what it often takes for us to get away with what we are motivated to do anyway.

I don't see a motivation that the Kerchers would be motivated to harm Amanda Knox other than their belief that she killed their daughter. In this context, what do you think is the underlying motive that they are engaging in self-deception to accomplish?