Midnight and Noon

OK. My wife and I were having a debate today about why Noon is considered PM and midnight AM. She tried various logical approaches to convince me but none of them seemed logical to me. She kept saying things like, "Noon has to be PM because if you add one minute, you are in the PM." My response, "On what logical grounds are you adding one minute? Could you not just as easily say, 'Subtract one minute and you are in A.M.?'"

I am of the opinion that the use of PM for noon has no logical foundation. It is merely a question of customary usage. What do you think?

P.S.: If you are wondering why we are spending time on this, chalk it up to social distancing.

"On what logical grounds are you adding one minute? Could you not just as easily say, 'Subtract one minute and you are in A.M.?"

No you can't, because that would be 11:59am, not 12 something. 

It is a little bit odd and the confusion is because you're at 1am, 2am......11am, then suddenly 12pm. It's illogical from the point of view of reaching 12, but if you think of as a day being 2 groups of 12 hours, you're really starting each count from zero. You only say 12:01 because it says 12 on the clock face. 

Or another way to look at it is, am and pm stand for ante and post meridian. Meridian means midday, and as soon as 12 in the afternoon strikes you are past midday, so it's pm. 

I'm afraid your opinion is factually wrong :-)

My wife and I were having a debate today about why Noon is considered PM and midnight AM.

If that is your typical debate, then congratulations on a successful marriage!

Noon has to be PM because if you add one minute, you are in the PM.

You are correct in that this makes as much sense as saying, "Noon has to be AM because if you subtract one minute you are still in the AM." This kind of thinking is similar to the Argument of the Beard .

I am of the opinion that the use of PM for noon has no logical foundation. It is merely a question of customary usage. What do you think? 

I would think this is a Google-able question with a definitive answer. I am not willing to do the research, but I bet it is :)

The point where the sun is at its highest point in the sky is referred to as 'noon' or 'midday'. This means you are no longer in morning. This also marks the halfway point of the day, hence PM (which does not, as I assumed, stand for 'post morning', but rather 'post meridiem' - or 'after midday').

AM means 'ante meridiem', or 'before midday'. Since 12am is technically 0 o'clock (as the day starts again from there), it is fine to refer to midnight - or 12 - as 'am'.

(Fun fact: it's technically wrong to say '12pm' or '12am', because 12 is neither before midday nor after. Instead, you should say '12 noon' or '12 midnight'. However, it is custom to do so because clocks often require that designator).

I believe it might be customary.

The difficulty is that we take time to do anything, so logically, "now" is already late by the time [ahem] it's expressed.  It's why electronics are used to time winners of races.

If you say "noon", does anyone ask "which noon?"  Twelve noon is redundant.