American traditions and the American ethic require us to be truthful, but the most important reason is that truth is the best propaganda and lies are the worst. To be persuasive we must be believable; to be believable we must be credible; to be credible we must be truthful. It is as simple as that.
Bio: Heinz Haber was a German physicist and science writer who primarily became famous for his TV programs and books about physics and environmental subjects. His lucid style of explaining hard science has frequently been imitated by later popular science presenters in Germany.