What the announcer at the London underground station said this morning:
- We have no reports of unplanned station closures.
What he did not say:
- There are no reports of unplanned station closures. Perhaps he did not say this because there could be such reports, which he or his station have yet to receive. In either case – whether he had received such reports or not – he would not be able to state truthfully that there were no such reports.
- There are no unplanned station closures. Perhaps he did not say this because stations could be closed without this fact having yet been reported, and so without his knowing this about them.
- No stations are closed. Perhaps he did not say this because stations could be closed intentionally and with forethought, for instance, for scheduled maintenance. Indeed, such a statement would in fact be false as there several London underground stations which are permanently closed, eg Aldwych Station.
- All stations are open. Perhaps he did not say this because stations could be neither open nor closed, for example when they are in transition from one state to the other, or else due to quantum uncertainty.
One has to be so careful in what one says, as I have remarked before.