What people with disabilities (current, or subsequent) should be concerned about is Singer's desire to assess value to other people's lives in order to determine how much should be spent to preserve them. Deep into the essay he delves into polling and mathematics and economics to assign value to human lives, especially those who have disabilities.
"One common method is to describe medical conditions to people — let’s say being a quadriplegic — and tell them that they can choose between 10 years in that condition or some smaller number of years without it. If most would prefer, say, 10 years as a quadriplegic to 4 years of nondisabled life, but would choose 6 years of nondisabled life over 10 with quadriplegia, but have difficulty deciding between 5 years of nondisabled life or 10 years with quadriplegia, then they are, in effect, assessing life with quadriplegia as half as good as nondisabled life. (These are hypothetical figures, chosen to keep the math simple, and not based on any actual surveys.) If that judgment represents a rough average across the population, we might conclude that restoring to nondisabled life two people who would otherwise be quadriplegics is equivalent in value to saving the life of one person, provided the life expectancies of all involved are similar."
Singer then begins to suggest a standard called the " quality-adjusted-life-year," a factor he is willing to compute by allowing people with disabilities to judge their lives on the basis of prospective cure.
"If we do that, and we find that quadriplegics would not give up even one year of life as a quadriplegic in order to have their disability cured, then the QALY method does not justify giving preference to procedures that extend the lives of people without disabilities over procedures that extend the lives of people with disabilities ... This method of preserving our belief that everyone has an equal right to life is, however, a double-edged sword. If life with quadriplegia is as good as life without it, there is no health benefit to be gained by curing it."
Singer's argument has three flaws, as I see it from down here in my wheelchair.
If "QALY" is a judgment value, why should we not apply the standard to those who live unhappily in poverty or constrained by the rigors of racial discrimination?
Why does Singer believe it is possible to use mathematically objective formulas to assess other people's subjective appreciation of the value of their lives?
Do those who might support this "quantification of life" understand that this same logic can be applied to any interaction between the individual and the collective, which given Singer's record suggest pre-natal screening and QALY-applications to euthanasia?