Models in which human beings are always maximizing their utility perfectly are the simplest kinds of models. But it is hard to maintain that children are always maximizing their own utility perfectly. In a discrete-time model, it is easy to have an initial period in which someone is not nonrational, followed by later periods of full rationality. But In continuous time, there are likely to be an in-between period in which some types of decisions are close to full rationality, while other decisions are far from fully rational in advancing self-interest. (For example, this post on the Edutopia blog talks about the “hyperrational adolescent brain,” but is about anything but.)

In On Liberty, Chapter IV, “Of the Limits to the Authority of Society over the Individual” paragraph 4, John Stuart Mill has to face the lack of full-scale rationality on the part of children, using the phrase “self-regarding virtues” to talk about the kind of rationality that allows one to advance one’s own interest. He writes:

I am the last person to undervalue the self-regarding virtues; they are only second in importance, if even second, to the social. It is equally the business of education to cultivate both. But even education works by conviction and persuasion as well as by compulsion, and it is by the former only that, when the period of education is past, the self-regarding virtues should be inculcated. Human beings owe to each other help to distinguish the better from the worse, and encouragement to choose the former and avoid the latter. They should be for ever stimulating each other to increased exercise of their higher faculties, and increased direction of their feelings and aims towards wise instead of foolish, elevating instead of degrading, objects and contemplations. But neither one person, nor any number of persons, is warranted in saying to another human creature of ripe years, that he shall not do with his life for his own benefit what he chooses to do with it.

Notice that in American custom, we tend to add to the kind of deference John is recommending for another adult’s decisions in regard to that adult’s own life, a deference for a parent’s decisions in regard to that parent’s own children. But the logic is unavoidably weaker for deference to parent’s decisions about their own children than it is for an adult’s decisions regarding his or her own life. 

One interesting area where our culture is shifting in regard to parent’s decisions about their own children is in our attitudes towards spanking. When I was a child, we children took the possibility of spanking (including many elaborated threats of spanking) and sometimes the reality of being spanked for granted. Not long into my experience as a father myself, I realized that social tolerance of spanking was waning. And nowadays, parents who spank their children often have a niggling, if perhaps exaggerated, fear that child-welfare arms of the government (“Social Services”) will punish them.   

John Stuart Mill allows for the possibility that compulsion might be necessary in bringing up children. And I find it hard to rule out the possibility that there may be situations in which some form of corporal punishment for a child may be the best available option. But compulsion (of which corporal punishment is only one type) should only be used when absolutely necessary, since it tends to have unwanted side effects. For example, in “John Stuart Mill Argues Against Punishing or Stigmatizing, but For Advising and Preaching to People Who Engage in Self-Destructive Behaviors,” I wrote

…punishing and stigmatizing may often be ineffective because the elements of a riven psyche one wants to encourage may have trouble seeing a punisher or stigmatizer as friendly.