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".

A very tall man once asked a question after my talk. Before beginning his question, he explained that the reason he was standing up is not to be intimidating but rather to make eye contact. His question was essentially "are we really interested in moral motives? Isn't it all about action?". I pointed out to him that it was not enough for him to do the right thing - stand up - but he also wanted me to know that he is doing it from the right motive or for the right reason - to make eye contact, rather than to be intimidating. Voila, moral psychology.

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.

Sometimes I suspect that there are two prototypes of philosophers who write about humans - I call them "celestials" and "terrestrials", without implying that celestials have their heads in the clouds or that terrestrials have theirs buried in the ground. The difference between these two types is not so much in their theories but in whether or not they would find it a very sad thing if it turned out that the only way a human is superior to a wolf is this: the human brain is significantly more capacious and complex.

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.

The fact that only humans above a certain age can be morally virtuous, rather than babies or cats, means that that being moral requires some cognitive ability. If virtue is about desires, it is worth remembering that you can't desire some things without being able to conceive of them. Suppose a virtuous person will desire to make people happy and desire to tell the truth. You can't desire to make people happy without having the concept "happy" and you can't desire to be truthful if you don't have have the concept "lie", so a cat or a baby cannot desire these things.

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".