If we rely on the rights response, however, we may be able to avoid some of the difficulties raised by sentience arguments. It is at least arguable that rights theorists see as necessary for status as a right holder. Under a rights view, a fetus arguably cannot be analogized to a primate that is to be used in experimentation, or to a cow that is to be consumed by human beings, because the fetus does not possess the qualities normally associated with person hood. Of course, the rights theorist can argue that fetuses may have moral rights even if they are not subjects of a life because that criterion is only a sufficient and not a necessary on for having rights. It should be noted that Singer uses his respective theory to condemn abortion.
Singer openly endorses choice and, when justified by the consequences, even infanticide.
Singer also argues that the subject of a life criterion is inexact and that in the case of a newborn infants and fetuses of mature gestation, we should probably go in favor of granting rights. But that would only mean that there was a conflict of rights between the mother and the fetus. However, Singer makes it clear that fetuses in early term do not have moral rights. Whether chooses an approach such as Singer's it must be understood that these theoretical frameworks have been developed largely in context in which there are conflicts between separate entities. In particular, these viewpoints address what we should do when we are confronted with a conflict between, for example, a chimpanzee that is to be used in experimentation and the vivisector that seeks to use the chimpanzee.