 One might attempt a more sophisticated explanation of the notion of ruling out, for instance in terms of information theory, or perhaps possible worlds. One may claim that a statement ‘rules out’ something insofar as there are situations, or worlds, at which it fails. In this sense, ‘Everything is true’ does rule something out. But now, it is this account of propositional meaning which can be challenged in general. If mathematical truths have a strictly necessary status (which may safely be assumed here), Fermat’s Last Theorem rules out nothing: being a necessary truth, it holds at all possible worlds. But it is perfectly meaningful; people wondered whether it was true or false for centuries; and its proof by Andrew Wiles was a substantial discovery.