I believe that there is a necessary connection in both directions between the physical and the mental, but that it cannot be discovered a priori. Opi… - Thomas Nagel

The distance between oneself and other persons and other species can fall anywhere on a continuum. Even for other persons the understanding of what it is like to be them is only partial, and when one moves to species very different from oneself, a lesser degree of partial understanding may still be available. The imagination is remarkably flexible. My point, however, is not that we cannot know what it is like to be a bat. I am not raising that epistemological problem. My point is rather that even to form a conception of what it is like to be a bat and a fortiori to know what it is like to be a bat, one must take up the bat's point of view.

Common sense doesn't have the last word in ethics or anywhere else, but it has, as J. L. Austin said about language, the first word: it should be examined before it is discarded.

Ethics increases the range of what it is about ourselves that we can will—extending it from our actions to the motives and character traits and dispositions from which they arise. We want to be able to will the sources of our actions down to the very bottom.