Truth is for striving at, for the sake of good collective action. With new media technologies, it seems that falsehoods can spread faster and further than ever. And with new norms of public discourse, while being caught in a lie would once end a politician’s career, today it is shrugged off, which has profound implications for democracy. Does the truth no longer matter? This optimist’s guide to truth argues that the problem of truth is an ancient one. It contends that truth is the best device we have for coordinating collective decisions and actions, and that, while the truth itself is perpetually elusive, the concept of truth as a target ideal to strive for is supremely useful. If we do not strive for truth, our decisions will be risky at best, often foolish and sometimes disastrous. This longstanding problem will not be solved with modern technology or regulations, but with measures we must all apply: mindfulness, humility, cooperation and optimism.