If somebody can't read Paradise Lost, for example, it doesn't necessarily mean they can't read.
It'd be a shame, especially for a British adult. They should know Milton's most important work.
I do agree; I was trying to make the distinction between "literate" and "educated". I would easily believe that 99% of people in most Western countries were
literate. However, I would also believe that much less than 99% are
educated. Hell, I read a lot of books in the 4th and 5th grade that were far above my reading level. I was literate at that age, however, it wasn't until I was further educated that I understood they were more than just "oh cool, a big white whale...I hope he catches him".
So, indeed it would be a shame for anyone to not be familiar with
Paradise Lost. They could still be literate though. It would just be the bare minimum of literacy.
A lot of people seem to think that if 99% of people are literate, we're doing very well educating our population. 99% need to be educated, not just literate.