I am indebted to Wesley J. Smith at Second Hand Smoke for a link to a recent article by Peter Singer, noted Utilitarian philosopher at Stanford, "Peter Singer: Germ of a new debate on the ethics of life."
To give you some idea of how Professor Singer thinks about us humans, consider the following extended discourse from the article.
For example, when President George W. Bush announced in 2001 that the US would not fund research into new stem-cell lines that are created from human embryos, he offered the following reason: Like a snowflake, each of these embryos is unique, with the unique genetic potential of an individual human being. But it is precisely this reasoning that is threatened by what Hwang and his team claimed to have achieved. If it is the uniqueness of human embryos that makes it wrong to destroy them, then there is no compelling reason not to take one cell from an embryo and destroy the remainder of it to obtain stem cells, for the embryo's unique genetic potential would be preserved. This possibility highlights the weakness of the argument that abortion, too, is wrong because it destroys a genetically unique human being. By this reasoning, a woman who finds herself pregnant at an inconvenient time could have an abortion, as long as she preserves a single cell from the fetus to ensure that its unique genetic potential is preserved. But it seems absurd that this should make any difference to the morality of aborting the fetus. If, at a later date, the woman wants to have a child, why should she use the DNA of her earlier, aborted fetus rather than conceiving another fetus in the usual way? Each fetus - the one she aborts and the one she later conceives through sexual intercourse - has its own unique DNA. In the absence of special reasons, such as a change in sexual partners, there seems to be no reason to prefer the existence of one child to that of the other.
In other words, all of Professor Singer's thought about human beings is confined to a material framework. Within that narrow framework, he is a very able thinker. He would undoubtedly be the first to admit that his thinking is materialist. What he would undoubtedly deny is that there exists anything in reality, like God or free will, for example, that requires a non-material framework to understand or to deal with. He might also deny the potential intelligibility of an extra-material framework. This is somewhat likely, since his Utilitarianism is largely descended from the family of Positivist philosophies. Where he and many others have failed to dig deeply into their own philosophy is in the area of the intelligibility of material value systems. Such systems always end up being completely circular.
What may be instructive for those of us who would try to defend the inviolability of human life in the public arena is that all attempts to do so from purely material considerations are doomed to failure. President Bush's argument about the uniqueness of each person is a case in point, as Prof. Singer so ably demonstrates. Any such defense will end up appealing to the gut feeling that each person is important, but without having any material explanation of why. That's because there isn't any. What value does an Einstein have if the only value any person has is purely material? I should think we'd all prefer to commit species suicide in order to prevent the existential equivalent of sepsis, hell on earth, knowing damn well that all of our earthly endeavors will ultimately mean absolutely nothing as the universe dies a heat death.