This Saturday is the Fourth of July — and it’s a big one. Two hundred and fifty years since the Declaration of Independence. In that time, this country has done extraordinary things. It has built one of the most diverse democracies on Earth, a haven where people can speak freely and chase a better life. And it’s done real harm: it took land by force, enslaved millions, broke treaties and lives. So here’s the hard question this Fourth of July: Wh…