Why is "Defiance of Nature" Still Invoked?

Healthy life extension defies nature - that is an argument you will hear a great deal of if you make a point of advocating longer, healthier lives. (Alongside the Tithonus Error and poorly considered complaints about boredom). By that criteria, however, houses, heating, medicine and all the other trappings of modern society also defy nature - they are very unnatural indeed. Alternatively, one could view them as the natural result of the natural human inclination to effect change in the world. So something deeper is at work here; the charge of defying nature is applied very selectively. Why? Russell Blackford's latest column at Betterhumans is the first part in an examination of "The Supposed Sin of Defying Nature":

Appeals to what is "natural" have a long history in policy debates about unpopular practices - such as homosexual acts, technological innovations and, particularly in recent times, manipulating DNA. The assumption is that there is something wrong morally about interfering with nature's processes, or defying nature itself - however, exactly, those ideas are to be understood.

You'd think that any concept of the inviolability of nature would long have been abandoned by philosophers, ethicists and cultural commentators. But sadly it isn't so. Nature's inviolability is still a club to bash any controversial practice or technology that conservative thinkers dislike.

John Stuart Mill's essay On Nature seemingly exploded the whole idea more than 100 years ago, but it persists in 21st century policy debates. It's like a vampire with a stake through its heart that refuses to die. Choose any of a vast range of controversial topics, from gay marriage to genetic enhancement and beyond, and you'll find a few thinkers willing to argue that it must be stopped because it defies nature.

And so we're left with two questions: Why does this argument persist? And is there anything that we can do about it?