6.36311 That the sun will rise tomorrow is an hypothesis; and that means: we do not know whether it will rise.
Cf. Wittgenstein’s later remark (in CV?) about how we might see the earth and sun from space and see that the sun will rise tomorrow. Since we don’t occupy such a vantage point, we don’t know if it will rise. But this is as much a fact about us as it is about the workings of the universe. The regularity of the laws of nature is not an hypothesis, is it?