The distinctions derive, I think myself, from a specially realistic feature of Aristotle’s thought-that he never forgets the fact that we were all once children. To read almost any other famous moral philosophers is to receive the impression that we, the intelligent adult readers addressed, sprang fully formed from our father’s brow. That children form part of the furniture of the world occasionally comes up in passing(about as often as the mention of non-human animals), but the utterly basic fact that we were once as they are, and that whatever we are now is continuous with how we were then, is completely ignored.
We all know that there is a difference between being a child and being and adult-and we all know that the difference is not merely physical. ‘When I was a child’, says St Paul, ‘I speak as a child, I understood as a child, I thought as a child: but when I became a man, I put away childish things.’ We manifest that knowledge in our ascriptions of moral responsibility-albeit often with great difficulty-regarding intentional homicide committed by eight-year-olds, or those with a ‘mental’ age of eight, differently from when it is committed by those who have ‘reached the age of reason’. So in the moral sphere we do assume there is a distinction between being mentally a child and mentally an adult. But what is it? Most moral philosophers have nothing to say relevant to this question because, having overlooked the fact that the rational adult moral agents they are addressing were children, they do not see it as a problem. But Aristotle does-and hence the distinctions. Neither distinction is entirely unfamiliar in modern philosophy. Many philosophers have wanted to distinguish acting from reason from acting from desire, and many have given accounts of special forms of rational wanting. But the distinctions, as thus drawn, are both technical and highly contentious, whereas the distinction between being mentally an adult and mentally a child is neither. Moreover, they tend to be presented as hard and fast, whereas, as we know, the transition from childhood to adulthood is a continuum; there is no precise point at which the change occurs. Although I would not stake my life on the impossibility of someone’s coming up with the necessary and sufficient conditions for ‘acting from reason’ in the way we, typically, do, and animals and small children do not, I am quite certain that any such analysis would have to embody, somehow, that continuum.