So 12:01pm is in the afternoon and even going further than that, 12:00:01pm is in the afternoon as well but 12:00pm is midnight?
It makes sense when you're talking about it on a 24 hour clock but not when you are talking in the terms that I am using above...
win-win:
"The American Heritage Dictionary of the English Language (Fourth Edition, 2000) has a similar usage note on this topic: "Strictly speaking, 12 a.m. denotes midnight, and 12 p.m. denotes noon, but there is sufficient confusion over these uses to make it advisable to use 12 noon and 12 midnight where clarity is required."