In the notes collected as On Certainty-composed, of course, long before the Apollo missions-Wittgenstein imagines a tribe whose members believe that they travel to the moon.2 Perhaps, he says, this is how they interpret their dreams; and he notes how difficult it might be to argue them out of their conviction. These reflections lead to the following passage:
108 ‘But is there then no objective truth? Isn’t it true, or false, that someone has been on the moon?’ If we are thinking with our system, then it is certain that no one has ever been on the moon. Not merely is nothing of the sort ever seriously reported to us by reasonable people, but our whole system of physics forbids us to believe it. For this demands answers to the questions ‘How did he overcome the force of gravity?’ ‘How could he live without an atmosphere?’ and a thousand others which could not be answered. But suppose instead of that we met the reply: ‘We don’t know how one gets to the moon, but those who get there know at once that they are there; and even you can’t explain everything.’ We should feel ourselves intellectually very distant from someone who said this.