It was seen in the last chapter that values other than knowledge mean that the route by which a decision is reached may in some circumstances be as important as the decision itself. It is not enough to get the right answer. It must also be got in the right way. Sometimes it may be preferable to have a less good answer reached by a better route. However the constraints imposed by the route may be tighter than was there suggested. Sometimes, however good the answer, there is no permissible means by which it may be reached. Sometimes only one route, or a tightly constrained group of routes, is morally permissible. A natural candidate for such a constraint is that permissible routes should respect the value of autonomy, the principle that people should have control of their own lives.