In this chapter I apply the view of psychopathy developed in Chapter 2, to the account of moral responsibility as responsiveness to reasons developed in Chapter 1. I begin by considering the question of what reactive attitudes, if any, we should hold towards psychopaths, engaging with arguments by Piers Benn and Patricia Greenspan. I then turn to the question of whether psychopaths are responsive to reasons. I argue that evidence of psychopaths’ reasoning impairments, including those suggested by the famous ‘moral/conventional distinction’ experiments carried out by James Blair, may be enough to call into question the reasons-responsiveness of some psychopaths, but that other, even ‘hard-core’ psychopaths, may not exhibit such deficiencies. However, I argue that these psychopaths, though not oblivious to reasons, may be impervious to them, that is, unable to recognise them as reasons which bear on their own choices. I then argue that the specific reasons to which these psychopaths are impervious are reasons stemming from the rights, interests and concerns of other people, and that they are impervious to them because they are unable to see other people as sources of value.