There is a perfectly legitimate argument to be made that the President of the United States should just sit back and take all attacks and insults hurled his way, even when the magnitude of the attacks is unprecedented. Donald Trump has chosen to ignore that philosophy. In case people aren’t aware by now, when Donald Trump is attacked, he fights back, even when he probably shouldn’t. Whether it’s a war hero like John McCain, the parents of a war hero like Humayun Khan, or just some morning talk show hosts, Mr. Trump feels the need to retaliate for criticism against...