Can you correctly match ‘a.m’ and ‘p.m.’ to noon and midnight? The answer can be tricky, but it isn’t quite as tricky as some think.
We recently received a complaint at my real job about the use of a.m. and p.m. with the numeral 12 when we’re talking about noon and midnight.
Before reading the specifics, I would have guessed the complaint would have suggested there’s no a.m. or p.m. Instead of those little abbreviations, you should use the terms noon and midnight to avoid any confusion.
I would agree with that. In fact, I suggested that very tactic years ago on this blog.
That wasn’t the complaint. Instead, this viewer complained that we were wrong to place a p.m. after the 12 when referring to noon. He claimed that noon is still 12 a.m. and that midnight is still 12 p.m. The abbreviation, he said, doesn’t change until 12:01 in both cases.
Well, that’s not quite correct.
If you search a variety of sources, you’ll get a variety of answers. There are people who claim that the abbreviation shouldn’t change until the clock changes. There are others who claim the change happens on the dot of 12 o’clock. Others argue that noon and midnight are right on the line and shouldn’t be labeled as a.m. or p.m.
That last group prefers the advice I gave in 2018: avoid the number and use noon or midnight to eliminate confusion.
Here’s why it’s tricky.
The abbreviation a.m. stands for “ante meridiem,” which means “before noon.” That little p.m. stands for “post meridiem,” or “after noon.”
The gripe is that when it’s 12 on the dot, it’s neither before nor after noon. It’s noon exactly.
If you really want to argue a point, I’ll let you fight that fight all you like. I’m not going to play along for a very simple reason: since a specific time is a fixed moment, once you reach that precise moment, the moment has passed.
Time stops for no one, you know.
When the clock reaches 11:59 a.m., it’s still before noon, so there’s no question that the a.m. applies. But once the next second advances, we’re on the other side of noon.
It’s like looking at a person’s death: Once they die, they’re dead. The moment of their death ends that life. Even at the millisecond on which they die, death has occurred. You can’t say they don’t “officially” die for another minute.
Let’s say your clock says 12 noon. But halfway through that first second of noon, the precise time could be expressed as 12:00.5. That fraction of a second is still a point that falls after noon. There’s no question that the change to noon requires p.m.
Likewise, the change to midnight requires the change to a.m. At that point, you’re counting down to the next 12 o’clock not two 12 o’clocks away.
Please, please for the love of all things holy, just use noon and midnight to avoid hair-splitting like this.
It would make everyone’s lives easier.