Mr Pfeiffer has found a correlation between declining rates of children being spanked (or otherwise punished physically) and subsequent decreases in violent crime.
In America in 2006-07, according to Human Rights Watch, more than 200,000 children were beaten by their teachers with a stick as a punishment. They overwhelmingly lived in the southern states and in Evangelical families. Two studies in 2010 showed that only 15% of American children are raised by their parents without any physical violence at all. To Mr Pfeiffer, this is one (of admittedly several and complex) factors, that explain why Americans own more guns, commit more crime and punish more severely than western Europeans. The conclusion, suggests Mr Pfeiffer, is that everybody, including Americans, should try raising kids with what he calls “Liebe statt Hiebe” (love instead of beatings).