One objection emerges when we roll libertarian logic out to its logical conclusion. If we were to reform the law so as to allow competent adults absolute, arbitrary autonomy over their own lives, then it would have to permit consensual vivisection and killing. In other words, should an individual consent to being mutilated and killed-say for sexual gratification-then the law would have no objection. In its eyes, the individual would be master of his own life and if he should choose to spend it in what other people consider to be a macabre fashion, then that would be his business and his alone.
In case this sounds just too bizarre to be worth considering, we should remember that in 2004 Armin Meiwes was tried in Germany for mutilating, killing and eating a 43-year-old computer engineer, who consented because, according to the judge, "he wanted to get the kick of his life", reported the Guardian, on 31 January 2004. The fact that Meiwes was convicted of manslaughter, and not just acquitted, is witness to the commitment of German law — as of all traditional Western law — to some concept of the objective worth of human life that is independent of the subjective preferences of individuals. In spite of his consent, the computer engineer's life had a worth that both he and his killer had violated: that is why Meiwes was punished. It follows from this that if English and Scottish law wishes to maintain a commitment to upholding the objective worth of human life, then it can't grant to individuals absolute, arbitrary autonomy over their lives.
I could let this part of the argument rest there. I could presume that every reader agrees that it would not be desirable for Britain to become a society where consensual cannibalism is regarded as a permissible lifestyle and that therefore the principle of arbitrary autonomy is not one that English and Scottish law should incorporate. But let me push the argument one stage further and try to explain my position. First, I appeal to the common sense notion that someone can choose to squander or waste his own life. Such a notion certainly makes sense in terms of my own experience. From what others say and write, it would appear to make sense in terms of theirs, too. But if it does make sense, then that is only because we recognise that our life might actually have an objective worth that we sometimes choose to ignore — that it has an objective worth that can stand over and against us in judgment upon our own free choices. It makes sense only insofar as our autonomy is not arbitrary, but is responsible to a given moral context.
Further, if we were to regard the individual as the sole arbiter of the worth of his or her life, then how could he/she continue to oblige the care and commitment of other people? If the worth of your life is entirely contingent upon your judgment and if I view your judgment as wrong-headed, why should I expend my time and energy in supporting your life? Suppose that you value your life rather more than I value it. Why should I prefer your judgment to my own? Perhaps indifference or self-interest would move me to "respect" your judgment in the thin, negative sense of not interfering with it. But such arm's-length respect falls a long way short of positive care. One problem with dissolving human worth into individual freedom, instead of making individual freedom serve objective human worth, is that it becomes very hard to see why that worth should command our neighbour's love. Another problem is that when arbitrary autonomy severs itself from responsibility, it haemorrhages its own value.
A third reason why the law should not incorporate the principle of absolute, arbitrary individual autonomy is because the private and the public realms are not in fact sealed off from each other. What we do and how we form ourselves in our so-called "private" relations does inform how we behave toward others in "public". If society tells its members, through the law, that a life spent in drug addiction or lethal masochism or ended early in suicide is quite as acceptable as any other — so long as it is freely chosen — then those who choose such lives will become prey to passions that will drive them to abuse and violate their neighbours. The drug addict's passion for a "high", the suicide's passion to escape and the sado-cannibal's erotic passion to penetrate and consume render them incapable of respect for the legitimate claims of other people. The drug addict will assault and rob to get money for his next fix, the suicide will end his own life no matter how many other lives he ruins as a result and the Armin Meiweses of this world will not be as solicitous of their victims' consent the second time around.
The notion that we are all rational choosers is a flattering lie told us by people who want to sell us something. They want a free hand in making a profit out of our fears and desires. The less flattering truth is that much of the time we are driven by social and psychic forces that we barely understand — and even less control — and that hinder us from paying attention to other people. We creatures of passion need the support of legal and social constraints to become the kind of people who are capable of looking beyond their own felt needs to heed the claims of their neighbours. The problem with the libertarian principle of arbitrary autonomy is that it would rob us of this support.