 As we have seen, to characterize something as possessing the agency distinctive of living things requires bringing to bear norms for the life form of that individual; this is no less true in our own case. Of course, humans are capable of various modes of living, and in light of such diversity, it is questionable whether there is any characteristically human life, and so, whether there is any univocal sense of ‘good human’. Foot acknowledges that humans are rational animals and she believes this characteristic introduces a ‘sea change’ in how we approach describing our own species; reasoning and the application of reasoning to action are features which are evaluated in human beings. As Foot writes, “[W]hile [non-human] animals go for the good (thing) that they see, human beings go for what they see as good” (NG 56). We are capable of responding to reasons in a distinctively explicit way, inasmuch as we act on some understanding of which things are good. In fact, it is precisely the application of reasoning to our action which interests us in ethical evaluation. Foot claims that vices are defects in our responsiveness to reasons for action, which constitutes a sort of natural defect in humans, and, specifically, individuals with vices have defective wills. Inasmuch as we have the capacity to reason about how to act, we are subject to a distinctive sort of evaluation; unlike other natural defects, which may simply be the result of bad luck, we are responsible for our conception of how to act, and therefore can answer to rational criticism of that conception.