The paper has not been published in written form except at (if you follow the link) Academia.edu. I have, of course, discussed similar issues elsewhere, including in my doctoral dissertation from Monash University and my 2014 book from MIT Press, Humanity Enhanced: Genetic Choice and the Challenge for Liberal Democracies.
In a way, the title is misleading, since I did not actually put a case against "radical enhancement" (radical technological enhancement of human capacities). Rather, I examined the case developed by Nick Agar, in his (then) recent book Humanity's End, and mused more generally about arguments along the lines of Agar's. The paper actually scrutinises such arguments with considerable scepticism.
A large sample (from near the end):
Nor are our current lives ideal, even if all goes as well as can be. Our lives inevitably diminish in many ways as we grow older. What we most certainly do know is that renuciation of radical enhancement, and particularly of [Aubrey] de Grey’s negligible senescence project, would not give us the option, as individuals, to go into the future with undiminished lives. Though we may live to eighty or ninety years, or even longer, we function near our peak for only a couple of decades, early in adulthood, and at our very best of health and strength for even less. Beyond the middle years of life, we are faced by a constant deterioration of our organs, organ systems, and capacities, which eventually spirals down into increasingly debilitating fragility. This is a kind of routine impoverishment of life that we should acknowledge without guilt or shame, despite propaganda about “aging gracefully” and the like.
In his book Better than Well: American Medicine Meets the American Dream (Norton, 2003), Carl Elliott discusses a suggestion by David Gems that the problem in growing older is “ontological diminution” meaning “a flattening of the conditions that sustain our existence.” Though Elliot is no admirer of enhancement technologies, he describes this process of diminution vividly: the dimming of senses and desires; the loss of capacities; the narrowing of perceptions and possibilities as the future grows more and more constricted.
There is something like a taboo against saying so explicitly and openly, but the aging process impoverishes our lives in very basic ways. If we are honest, halting the deterioration of our health, strength, and capacities is something that we have every reason to value, and I do mean right now, before any transformation of our values that new technologies may bring. We cannot, of course, imagine the detail of entire lives without the aging process, but it seems perverse to complain that removing the process, or drastically slowing it down to give us more time at or near our peak, would impoverish us.
Agar may well be correct, however, when he suggests that there is a limit to how much technological change we can absorb if it happens very abruptly. A series of sudden and radical changes in human capacities might well have a psychological downside. It might be shocking and alienating — like the impact of a military invasion by a technologically-superior culture. Even so, there would be gains. The overall outcome might not be a bad one when all things are balanced and considered. In any event, any radical enhancements of human capacities are more likely to take place over generations, allowing time for people and cultures to adapt.
In the end, we are confronted by a fascinating situation. First, I’ve suggested that seemingly scary new technologies such as human reproductive cloning may not be so scary after all when we think about their limited effects on individuals and societies. They may require regulation, but there is no good reason to ban them outright. Second, when we think of more futuristic and radical technologies, the position changes — but not necessarily in a way that justifies draconian legislation. We can imagine scenarios in which radical enhancement technologies change our societies deeply, perhaps undermining practices that we currently value. We can even describe in detail what some of the threatened practices might be, though we can’t be sure of the actual effects on them.
But none of this is a reason to step on the brake. Yes, the development of new technologies can threaten existing practices and attitudes, as has happened in the past with the printing press, railroads, motor vehicles, the contraceptive pill, the internet, and many other examples, but people generally adapt, and new social practices develop to incorporate the technology. These can then provide new sources of happiness and meaning.
Of course, I have not shown that all radical enhancements would be innocuous, or that they could be implemented with no social dislocation, or with no downside for people who might miss out. I have not tried to argue in a comprehensive way that all emerging technologies whatsoever should be accepted politically, subject only to minimal regulation (such as for safety). Nonetheless, it is well to beware of biases that can skew debate, making clear and rational analysis even more difficult. That is my main take-home point.
Often, it is assumed that we face a crisis in responding with sufficient urgency to the emergence of Frankensteinian technologies. I see things in a different light. If anything, the debates of the past decade or two show a crisis for liberal tolerance. We should insist, perhaps politely, perhaps more passionately, that policy makers in our modern liberal democracies require compelling reasons before they embark on programs of political coercion. We can object to distortions of public debate arising from feelings of disorientation or repugnance, undue deference to religious leaders and doctrines, fears of what might be lost from technological change, and the all-too-common impulse to reach for the crude tools of the criminal law.