Roger Daltrey of the Who sang it with a full-throated scream in 1971: “We won’t get fooled again!”

And yet, we still do. Oh, do we ever.

Remember this one from the presidential campaign? The “news story” that spread the lie that Pope Francis had endorsed Donald Trump for president? It was shared more than a million times. Or recall the faked report that the leader of the Islamic State was urging American Muslims to vote for Hillary Clinton.

With the proliferation of hoaxes, conspiracy theories, doctored photos and lies that look like news, it’s inevitable: We’re all chumps som...