Matthew, that 2008 Campbell study is only one in a long line of empirical studies looking at how religious education (and also secular private education) affect tolerance for the rights of others, as well as other democratic values and practices such as voter participation and volunteer work. The positive impact of religious and private education on civic values and practices is confirmed across the body of studies, giving us a level of certainty that we can never have as the result of just one study. Moreover, some of the studies use random assignment methods, increasing the confidence we can have in the results.
As is always the case in international comparisons, particularly when America is compared to Europe, we must beware of comparing apples and oranges. The public/private distinction does not line up with the religious/secular distinction in Europe the way it does in America. Still, it is undeniable that the president’s comments regarding Ireland’s schools resonate with a smear campaign, now in the closing phase of its second century, to demonize private and religious schooling in the United States. From the Know-Nothings forward, we have never been free of the great lie that private religious schools undermine tolerance—a lie that was false when it was deployed by Protestant bigots against private Catholic schools, and remains false today when deployed against all private schools by teacher’s unions whose professional mission is to keep their gravy trains running on time by destroying children’s lives.
The classic review of this evidence is Patrick Wolf’s article “Civics Exam.” Some studies too recent to be mentioned in Wolf’s article are mentioned in my recent overview of the research on school choice, titled “A Win-Win Solution.”
There are several good reasons that could explain why private schooling produces more tolerant a democratic citizens.
1) A large body of very high-quality evidence establishes that private schools are better at teaching academic subjects like math and reading. Why would we not expect them to be better at teaching tolerance? They’re better at teaching.
2) The fact that the school is chosen establishes alignment between parents and schools. Sociologists report that kids getting the same messages from multiple authorities consistently is important to effective moral formation.
3) Assigned public schools cannot situate moral messages in a deep view of the universe because families are forced to send their children there. They can yell at kids to be tolerant (and be honest, diligent, etc.) but they can’t explain why in any but the most mechanistic, reductive terms. Private schools are allowed to know how the universe works and what the meaning of life is, and that makes effective moral formation possible. This doesn’t always mean a religious view; it just means they’re allowed to be human and not just bureaucratic.