I don't think any of my desires or beliefs or other mental states are external to me. Many people will occasionally feel alienated from the motives for an action - "whatever possessed me to do that?". Note, however, that some people feel alienated from the white hairs that recently appeared on their heads - "who put them there?", they might ask the mirror - but the white hairs are still theirs. Similarly, I might feel alienated from an action or a mental state because it does not fit with my visceral self - image.

I don't think any of my desires or beliefs or other mental states are external to me. Many people will occasionally feel alienated from the motives for an action - "whatever possessed me to do that?". Note, however, that some people feel alienated from the white hairs that recently appeared on their heads - "who put them there?", they might ask the mirror - but the white hairs are still theirs. Similarly, I might feel alienated from an action or a mental state because it does not fit with my visceral self - image.

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.

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".

Sometimes we deliberate - for example when we plan a long trip or - if we are not math wizards - when we solve long division problems. However, if we deliberated every time we acted we would never get through the day. Most of the time, we act for reasons without deliberation. I am not just talking about cases of simple, habitual action, like brushing your teeth, but also about more sophisticated action.

When I see two owls and then two more owls and conclude that I see four owls, I am responding to reasons, and it better not be my choice to believe that two plus two always equals four. If I am a rational person, I will have that belief by necessity, whether I wanted to or not. So it's not that strange to discuss responding to reasons out of necessity.

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.