The duo studied samples of 806 children ages two to four and 704 children ages five to nine and then retested both groups four years later. The IQs of children between the ages of two and four who were not spanked ranked five points higher compared to those who were spanked in their same age group. Children who were five to nine years old that were not spanked were 2.8 points higher in IQ four years later compared to their spanked counterparts. ...These were not controlled studies. We know that IQ and personality disorders are largely inborn. All these studies show is that low-IQ misbehaving kids get spanked more. Black kids get spanked the most.
A study published in the Journal of Family Psychology by researchers at the University of Texas at Austin and the University of Michigan claims that children who get spanked are more likely to “defy their parents and to experience increased anti-social behavior, aggression, mental health problems and cognitive difficulties.“
The researchers and the libertarians reverse the causality here, and conclude that spanking causes low IQ and bad behavior. Similar reasoning would conclude that spanking causes black skin.
The dishonesty of these folks is apparent from their refusal to even mention the possibility of reversed causality. The anti-spanking research and advocacy is driven by unscientific beliefs about nonviolence and child rights.