On Tuesday, the Fourth of July, Americans will drink beer, eat hot dogs and celebrate 241 years of “life, liberty and the pursuit of happiness.” That means you get to do whatever you want, provided that you don’t interfere with anyone else.

Right? Wrong. Although the founders of our country certainly wanted to protect personal freedom, they didn’t see it as an end in itself. Their main goal was happiness, which was a shared condition rather than an individual one. We could only achieve it together.

And that’s precisely the ideal we need to reinvigorate in our frayed and fragmented republic right now. Too many of us have withdrawn from politics, seeking happiness in private. The ancient Greeks — whom the founders invoked incessantly — had a word for such a person: “idiot.” That meant a solitary individual, who didn’t participate in collective life.

Others of us have retreated into communities of the like-minded, refusing to commune with anyone outside of them. That brings us closer to the people in our tribe but alienates us from the nation, which cracks into jagged shards and pieces.

So it’s hard to be happy, at least in the way the founders imagined. America, they knew, was a great experiment. But it was destined to fail unless we conducted it in unison. ...