Campaigning in former President Reagan's hometown before last week's Illinois primary, GOP presidential hopeful Rick Santorum asserted that he was the only candidate "who stands on the pillars of what Ronald Reagan built as the modern Republican Party."Speaking in the shadow of a statue of Reagan, Santorum proclaimed: "Let the voice of Reagan be heard across this land."And it isn't just Santorum: During the GOP presidential debates, Reagan's name was invoked nearly 250 times by the GOP field.But many historians argue that if Reagan had a true heir, he or she might raise taxes, compromise with Democrats and put aside...