 Second, on either the threshold or the proportionality account we need a measure of that ability that marks the threshold or is simply progressively acquired. How much intelligence and understanding, for instance, is sufficient? In the first place this measure must be taken independently of any judgement of what is in the child’s best interest. That a child would choose what is taken to be in her best interests is at most evidence that she does have sufficient intelligence and understanding of the relevant issue. Her making such a choice is not a necessary condition of her having the requisite ability. Similarly the making by a child of a poor choice is not conclusive evidence of her general incapacity to choose for herself. Wise adults can occasionally make stupid decisions just as fools sometimes get it right.