In order for autonomy to discharge this duty, we should be able to say something about why it is itself of value; but this can be surprisingly difficult. To be more precise, there are various reasons for regarding autonomy as valuable, but none of them seem able to capture its importance for us. For example, it is certainly the case that autonomy can allow one to live a more pleasurable life, but this does not exhaust its worth. A life filled with pleasure but without autonomy would fundamentally lack something valuable; you would have grounds to reject the offer of such a life, and to protest if someone attempted to force your life into such a mould.
One apparent problem here is that autonomy is defined in terms of certain abilities or capacities, and it is natural to think of abilities as valuable not in themselves, but in terms of what they enable us to do. In a similar way, it would be odd to have any particular regard for a kettle unless one had some reason to value hot water. But autonomy is not merely one capacity amongst others, such that one could give it up and remain fundamentally the same. It is definitive of each of us as a person, as someone capable of rational behaviour, of choosing what to do, of voluntarily engaging with other persons. To the extent that we value this array of capacities, we must value autonomy. Conversely, to forgo autonomy would be to choose to give up the power to make any further choices.
It is worth pointing out that a life without autonomy is not thereby disconnected from any values. Animals can feel pleasure or pain; infants can respond to affection or coldness. Autonomy does not by itself introduce value into our lives, but it makes it possible for us to live according to a value or values. It is this which makes it the basis for treating others with dignity; and treating others with dignity requires regarding them in an important sense as equals. But to show this, I shall first have to examine what it is to respect the autonomy of others.