For Ursula Wolf, empirical differences concerning the dimension of suffering, which can be experienced by the respective moral subject, do not justify a graduated moral consideration. A moral subject’s ability to suffer, be it an animal or a human being, can only in rare exceptions be weighed against a higher moral good. Hence, it is not permitted to weigh, for instance, the joy of consuming pork against the suffering of a pig raised in factory farming. Furthermore, differences in the capability of reflection on the own suffering do not justify a moral gradation since some animal species, for example, cannot abstract from their pain, while human beings can partly do so. According to Wolf, only the ability to suffer is decisive for a moral judgment; those living beings which additionally have at their disposal a conscience of their own pain are worthy of protection on a higher level.

The presence of particular closeness, too, does not necessarily justify more rights for human beings. Wolf claims that a close social relationship can also exist between a human being and an animal.

Within the circle of human beings there would further exist very different types of relationships which do not justify a reduced worthiness of protection. This is the case particularly in situations where individuals, as opposed to the majority of human beings, do not possess full rational capabilities. Wolf thus underlines that we should not undertake any reduction in protection based on different social relationships concerning human beings with different rational abilities (e.g. patients in a coma) and that, analogously, we should not do so with respect to animals either.