In his apologetics for infanticide, Princeton bioethicist Peter Singer has used a baby with Down syndrome as an example of a killable infant based on utilitarian measurements. (He actually supports infanticide because babies -- whether disabled or not -- are, in his view, not "persons.")
To Singer, moral value primarily comes from intellectual capacities, and that means developmentally and cognitively disabled human beings (also, the unborn and infants) have less value than other human beings, and indeed, a lower worth than some animals.
Were society ever to adopt Singer's bigoted anti-human exceptionalism views, it would mark the end of universal human rights, opening the door to tyrannical campaigns against the most weak and vulnerable -- you know, the kind of people that the Singers of the world deem resource wasters.
It would also break the spine of unconditional love, as our children would have to earn their place by possessing requisite capacities.
Consider the recent statements by Singer, published in the Journal of Practical Ethics, in which he explains why he would adopt out a child with Down syndrome. He then expresses a profound bigotry against people with cognitive and developmental disabilities (emphasis added):
For me, the knowledge that my [hypothetical Down] child would not be likely to develop into a person whom I could treat as an equal, in every sense of the word, who would never be able to have children of his or her own, who I could not expect to grow up to be a fully independent adult, and with whom I could expect to have conversations about only a limited range of topics would greatly reduce my joy in raising my child and watching him or her develop.
"Disability" is a very broad term, and I would not say that, in general, "a life with disability" is of less value than one without disability. Much will depend on the nature of the disability.
But let's turn the question around, and ask why someone would deny that the life of a profoundly intellectually disabled human being is of less value than the life of a normal human being. Most people think that the life of a dog or a pig is of less value than the life of a normal human being.
On what basis, then, could they hold that the life of a profoundly intellectually disabled human being with intellectual capacities inferior to those of a dog or a pig is of equal value to the life of a normal human being? This sounds like speciesism to me, and as I said earlier, I have yet to see a plausible defence of speciesism. After looking for more than forty years, I doubt that there is one.
Invidious discrimination exists when equals -- e.g., all human beings -- are denigrated as unequal based on some category that the bigot believes reduces the status of the discriminated against human, e.g., racism, sexism, and Singer-style discrimination against people with cognitive or developmental disabilities.
But human beings and animals do not inhabit the same moral realm. It is not wrong or discrimination to view and treat us differently than we do them.
Moreover, the very concept of "speciesism" -- used liberally in animal rights activism and bioethics -- is inherently and invidiously anti-human because it reduces us to so many carbon molecules with no inherent value beyond our cognitive capabilities at the moment of measurement. To repeat myself, the idea of speciesism, like utilitarianism, makes universal human rights impossible to sustain intellectually.
Assuming such utilitarian values would destroy the principles of Western civilization. And never mind the real capacities of many people with Down, whom Singer mischaracterizes, or their extraordinary loving natures -- which I have yet to see Singer opine much about. To Singer, intellect trumps all.
That's bigotry any way you look at it, no different from racism, except that his victims are less able to defend themselves.
I have always found it odd that Singer faces little of the opprobrium society metes out to other bigots. Indeed, he was brought to Princeton from Australia and given one of the world's most prestigious chairs in bioethics precisely because of these attitudes.
Despite supporting the propriety of killing babies, I have no doubt that Singer will continue to be the New York Times' favorite philosopher.