During President Donald J. Trump's impeachment trial, we'll hear a lot of talk about our rules for governing. One frequent claim is that our nation is a democracy. If we've become a democracy, it would represent a deep betrayal of our founders, who saw democracy as another form of tyranny. In fact, the word democracy appears nowhere in our nation's two most fundamental documents, the Declaration of Independence and the U.S. Constitution. The founders laid the ground rules for a republic as written in the Constitution's Article IV, Section 4, which guarantees “to...