Barack Obama says he believes in universal preschool and if he's elected president he'll pump "billions of dollars into early childhood education." Universal preschool is now second only to universal health care on the liberal policy wish list. Democratic governors across the country -- including in Illinois, Arizona, Massachusetts and Virginia -- have made a major push to fund universal preschool in their states.

But is strapping a backpack on all 4-year-olds and sending them to preschool good for them? Not according to available...