A person is praiseworthy for a right action to the extent that her action manifests, and is rationalized by, good will, that is, concern for the right and the good, not necessarily under the description "right" or "good". A person is blameworthy for a wrong action to the extent that her action manifests, and is rationalized by, ill will - concern for the wrong and bad, also de re - or moral indifference - lack or deficiency of good will.

When you find yourself reluctant to sit on a chair because it had unexpectedly collapsed in the past you might shake your head and think "there, I'm so irrational!". But your reluctance to sit on a probably rickety chair is not irrational - you think it's irrational because you have a false view of what irrationality is.

I don't think we are all irrational every time we fail to see through an argument in a book, but suppose it's true about you. You are still more rational than you think you are. You are irrational in a minor way - believing a misguided theory of the nature of rationality - but rational in a major way - you respond well to probabilistic evidence as you go through the day.

Virtue is about wanting right and good things, not about being particularly good at thinking.

Suppose a student of mine writes in her exam that "morality is completely relative to culture, so nothing is absolutely right or wrong. Because of that, it is absolutely wrong to be culturally intolerant". This student, if she believes what she writes, believes a contradiction. She ought not to believe the contradiction - it's a basic epistemic norm. This is true even if she can't avoid believing it - no amount of studying will show her the light.

For those of us who want to have control over all our mental states, compatibilist substitutes - such as desiring what we desire to desire - will always be like being told, when you desperately want there to be a God, that yes, God exists, as God is simply the good within people.

Duties concern things that are voluntary. I do think that if you have a moral duty to bring me back the book you borrowed, that implies, roughly, that your doing so depends on your wanting to do so: if you want to bring me the book, you will. This is not the case if you are stuck at some airport due to a snowstorm, far away from me. This, however, is not the same as "ought" implying a metaphysical "can".