What was the highest mountain in the world before Everest was discovered?

Yes, I know that a number of pedants will read the title of this blog post and mutter under their breaths with a shrug of indignation:

‘What was the highest mountain in the world before Everest was discovered? Why, Everest of course. It was still the highest mountain in the world, even if nobody who knew of its existence knew how high it was.’

But for every 50 pedants who read this blog (yes, I’m afraid the ratio will be that high) there will be at least one metaphysician who will answer:

‘If...