Yale psychologist Alan Kazdin argues in Slate today that parents shouldn't spank children. He says studies find a host of negative consequences:

"The negative effects on children include increased aggression and noncompliance—the very misbehaviors that most often inspire parents to hit in the first place—as well as poor academic achievement, poor quality of parent-child relationships, and increased risk of a mental-health problem (depression or anxiety, for instance). High levels of corporal punishment are also associated with problems that crop up later in life, including diminished ability to control one's impulses and poor physical-health outcomes (cancer, heart disease, chronic respiratory disease). Plus, there's the effect of increasing parents' aggression, and don't forget the consistent finding that physical punishment is a weak strategy for permanently changing behavior."

Two quick thoughts about this. First, I wonder whether spanking, like any other parenting technique, might work better (or worse) for some children than others. We often want a single policy for all children, but since children differ widely in temperament, personality, and so on, it seems likely that no single policy would be appropriate in all cases.

Second, it is interesting to note that modern psychology seems to be catching up with . . . Herbert Spencer! Spencer argued in his 1851 Social Statics that children deserve the same respect as adults and are equally protected by the law of equal freedom; one consequence of this, he thought, is that corporal punishment of children--or what he called" coercive education"--is as unjust as slavery.