My fundamental thought is that the “logical constants” represent nothing. That the logic of facts does not allow of representation.Propositions represent objects (and their relations), i.e. facts. What must or should be done in any non-factual sense cannot be represented. "If...then" statements can all be replaced by propositions connected with the Sheffer stroke or by truth-tables, and truth-tables are like rules for a game. Nothing tells you that you have to play that game. The only necessity is logical necessity, which is the necessity of a game. Compare Anscombe:
in a divine law theory of ethics [...] what obliges is the divine law‑as rules oblige in a game.Here is more Wittgenstein on philosophy and the limits of the ethical/sayable (not the same thing, but they share a border):
4.113 Philosophy limits the disputable territory of natural science.
4.114 It should delimit the thinkable and therewith the unthinkable.
It should limit the unthinkable from inside, by way of the thinkable.
4.115 It will refer to the unsayable in that it presents clearly the sayable.
4.116 Everything that can be thought at all can be thought clearly. Everything that can be said can be said clearly.I think this backs up what I was saying about the limit in question being a kind of border between scientific facts (which Wittgenstein understands in a very broad sense--scientific facts are basically just facts, and maybe even all possible facts) and the unsayable. The unsayable is also unthinkable, so I don't think this should be regarded as any kind of mysticism. The unthinkable cannot be thought at all. There is no room here for 'grasping' or 'intuiting' the ineffable.