On Apr 2, 2014, at 8:29 PM, Brian E Carpenter <brian.e.carpenter@xxxxxxxxx> wrote: > In the supermarket the other day, I was handed a free sample > of Red Bush Tea, which is clearly not tea. I do not know > whether it is not-tea. As I mentioned to someone privately earlier, not-tea is the logical complement of tea, which is to say the complete set of all things that are not tea. Hence, Rooibos tea is not not-tea, although it is not tea.