# 12am / 12pm - Which is noon? which is midnight?



## Dalian

I'm confused~help me out [with the use of 12am and 12pm], thank you

Dalian


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## lsp

We've discussed this numerous times, one of those threads is here. You can find others with the Search function.


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## marget

Hi, 

Can anyone explain why we say PM for noon when it's exactly, not after, noon?  Does it have to do with the day beginning at 12:00 AM which is clearly before noon so we must use PM for lack of anything more precise to express the other 12 o'clock?

Thanks in advance!


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## foxfirebrand

We could look at 12N and 12M as ambiguously AM or PM, and be scrupulously mathematical about it forever-- but those of us who have to get on with the business of telling or keeping time have to pick one or the other to assign to each, and that's where convention gets imposed.  It's the same case with idiom, which is of course never logical-- it's just the way we say/do it, the way things have sorted out.  

I suggest we all switch to military time.  Noon is 1200 hrs and midnight is 0000 hrs (pronounced zero hundred).  The "wee hours" become "oh-dark-thirty."  Synchronize your timepieces on my mark-- three, too, won...click!  Problem solved, ball in your court, and smokem if you gottem.
.
.


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## Brioche

marget said:


> Hi,
> 
> Can anyone explain why we say PM for noon when it's exactly, not after, noon? Does it have to do with the day beginning at 12:00 AM which is clearly before noon so we must use PM for lack of anything more precise to express the other 12 o'clock?
> 
> Thanks in advance!


 
I suggest that it may come from digital clocks, the sort that have two "cards" on show, one with the hour, and one for the minutes.
The hour cards are 1 am, 2 am, 3 am, &c, and the minutes 00, 01, 02, &c.
The cards are on  wheels, so that a new card shows each minute.

So the clock shows 11 am :59, then 12 pm: 00, then 12 pm: 01, and so on. 

The makers were not going to have special cards with 12 noon and 12 midnight to show for just one minute - it would make the mechanism pretty complicated too.


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## JeffJo

Using "12:00 pm" for noon is only a convention, based on simple clocks, I agree.  A distinction had to be made, between noon and midnight, for simple clocks, so they used "am" for midnight, and "pm" for noon.  Language then followed the clock convention.

"PM" will be correct for times after noon, so it's reasonable enough to use exact 12:00 as the "click-over" point.  The click-over to PM at exact noon is made so that it _will be_ correct as the clock continues to run.

Strictly speaking, neither 'am' nor 'pm' applies to exact noon, or to exact midnight, but clocks incapable of displaying "noon" or "midnight" had to show _something._  In writing and printing, it would still be best to use "noon" or "midnight" when that's what's intended, but people often use the primitive and technically incorrect clock conventions.  Writing "12pm" for "noon" isn't really incorrect, it's just, oh, mechanical.


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## panjandrum

A.M. and P.M. start immediately after Midnight and Noon (Midday) respectively.
 This means that 00:00 A.M. or 00:00 P.M. (or 12:00 A.M. and 12:00 P.M.) have no meaning.
 Every day starts precisely at midnight and A.M. starts immediately after that point in time e.g. 00:00:01 A.M.
 To avoid confusion timetables, when scheduling around midnight, prefer to use either 23:59 or 00:01 to avoid confusion as to which day is being referred to.
*Source*


Taken from a link provided in:
*What time of day is 12AM.*


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## Sepia

foxfirebrand said:


> We could look at 12N and 12M as ambiguously AM or PM, and be scrupulously mathematical about it forever-- but those of us who have to get on with the business of telling or keeping time have to pick one or the other to assign to each, and that's where convention gets imposed.  It's the same case with idiom, which is of course never logical-- it's just the way we say/do it, the way things have sorted out.
> 
> I suggest we all switch to military time.  Noon is 1200 hrs and midnight is 0000 hrs (pronounced zero hundred).  The "wee hours" become "oh-dark-thirty."  Synchronize your timepieces on my mark-- three, too, won...click!  Problem solved, ball in your court, and smokem if you gottem.
> .
> .



Sounds like a good idea - but I must throw in some trivial info here: The way I learned it we'd never start a military operation at 0000h. It would start at 2359h or 0001h. Just with Murphy's Law in our minds - to make sure that nobody, absolutely nobody would have any confusion about the date and launch his attack 24 hours earlier or later.


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## mplsray

JeffJo said:


> Using "12:00 pm" for noon is only a convention, based on simple clocks, I agree. A distinction had to be made, between noon and midnight, for simple clocks, so they used "am" for midnight, and "pm" for noon. Language then followed the clock convention.
> 
> "PM" will be correct for times after noon, so it's reasonable enough to use exact 12:00 as the "click-over" point. The click-over to PM at exact noon is made so that it _will be_ correct as the clock continues to run.
> 
> Strictly speaking, neither 'am' nor 'pm' applies to exact noon, or to exact midnight, but clocks incapable of displaying "noon" or "midnight" had to show _something._ In writing and printing, it would still be best to use "noon" or "midnight" when that's what's intended, but people often use the primitive and technically incorrect clock conventions. Writing "12pm" for "noon" isn't really incorrect, it's just, oh, mechanical.



I largely agree. I would just take issue with identifying the clock conventions as "technically incorrect." That strikes me as example of the etymological fallacy, just as it would be to say that "It is technically incorrect to say that anyone is _melancholy_ nowadays because _melancholy_ means that a person has an excess of black bile, a theory which has been discredited." The meanings of _AM, PM_, and _melancholy_ depend upon usage, not upon on their origins.


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## panjandrum

There appears to be a convention that 12am is midnight, 12pm is noon - but that is not universal, else we wouldn't be having this discussion for at least the fourth time in WR Forums.


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## Packard

I *never* use 12:00 (AM or PM) *ever*!  (Except right here and now.)  For exactly the reason that this thread has been started.  It will (guanranteed) be a cause of confusion at some point or another.

I say:  *Midnight* or *Noon*.  You will never have any ambiguity if you use those words.

You still have to learn the difference because there will always be some less considerate writer who will use "12:00" and you will have to figure out what they meant.


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## JeffJo

panjandrum said:


> A.M. and P.M. start immediately after Midnight and Noon (Midday) respectively.
> This means that 00:00 A.M. or 00:00 P.M. (or 12:00 A.M. and 12:00 P.M.) have no meaning.
> Every day starts precisely at midnight and A.M. starts immediately after that point in time e.g. 00:00:01 A.M.
> ...



That link, unfortunately, is wrong.  "12:00 pm" does, in fact, have a meaning.  It means noon.  Terms in speech, or writing, have the meanings that people assign to them.  The idea of a day starting at midnight is also a human convention.  There's no such _natural_ division of days.

An example might help to illustrate why "12 pm" is used to mean noon.  Take three clock mechanisms, all highly precise and capable of keeping good time.  Attach one mechanism (A) to a display that shows time to the nearest minute.  Attach another mechanism (B) to a display that shows time to the nearest second.  Attach the third mechanism (C) to a display that shows time to the nearest 1/10 second.  Then look at what can happen around noon.

First, set all the mechanisms to switch the display to PM at their first display interval _after_ noon.  The following is what you'll get, when the time is 12:00:00 and 1/10 second, PM.

A. shows 12:00 AM - and it is _wrong._  The time is actually PM.
B. shows 12:00:00 AM - and it is _wrong._  The time is actually PM.
C. shows 12:00:00.1 PM - and it is _right._  Only this clock is right with its AM/PM display.

Two of the clocks are wrong on their AM/PM displays, just because of how the display is being operated.  If you set all three clocks side-by-side on a table and watch them, you will actually see two of the clocks being wrong about AM/PM.  The third clock will show you the other two being wrong, as you watch (even if all three clocks are equally accurate at keeping time.)

Now, change the way the mechanisms activate the displays, so that they all "click" over to PM at 12:00 exactly.  Then, you'll see the following at a time of 12:00:00.1 PM.

A. shows 12:00 PM - and it is _right._  Earlier it was wrong with its AM/PM display, but now it's right.
B. shows 12:00:00 PM - and it's _right._  This one also was wrong earlier, but is now right.
C. shows 12:00:00.1 PM - and it is _right._  This one is still right, as it was earlier.

All three clocks now agree with their AM/PM indicators, and they're all correct.  You'll never see one of the clocks showing the others to be wrong about AM/PM, just because of how the displays are activated.  What it took, to make the clocks agree, is merely the convention that 12 o'clock exactly is "pm."


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## Packard

All of which is why the military uses a 24 hour clock.

"Dinner is at 18:00 hours."


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## panjandrum

It really doesn't help to protest that 12pm has *a *meaning.
It is evident from all the discussion here and elsewhere that neither 12am nor 12pm convey a specific and reliable meaning.  
They are both ambiguous.
The longer the discussion goes on, the more apparent this becomes.


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## Packard

panjandrum said:


> It really doesn't help to protest that 12pm has *a *meaning.
> It is evident from all the discussion here and elsewhere that neither 12am nor 12pm convey a specific and reliable meaning.
> They are both ambiguous.
> The longer the discussion goes on, the more apparent this becomes.


 

My point exactly. Use *Noon* or *Midnight*.


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## mplsray

panjandrum said:


> There appears to be a convention that 12am is midnight, 12pm is noon - but that is not universal, else we wouldn't be having this discussion for at least the fourth time in WR Forums.


 
I agree. Nevertheless, when the usage is so lopsided as in is in favor of 12 PM being noon, it's a disservice to suggest to someone asking the meaning of the expression to suggest that there is anything other than a tiny possibility that when they read 12 PM it means midnight.

I'd like to point out that using the term _midnight_ itself is no guarantee of clarity. In fact, _midnight on July 13_ means both "midnight, the night of July 12-13" and "midnight, the night of July 13-14." Is there a consensus on which meaning is correct? Even if usage is strongly in favor of one over the other, surely there is even a _stronger_ consensus that _12 PM on July 13_ means "noon of July 13."


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## Forero

Not to mention that noon is closer to 1:00 pm when we have set our watches ahead for the summer.

But here is what has always bothered me about am and pm:  If 3 am is 3 hours ante-meridiem, shouldn't that mean 3 hours before noon (what we call 9 o'clock in the morning)?


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## Packard

The military has it right:  use a 24 hour clock.


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## Packard

mplsray said:


> ...I'd like to point out that using the term _midnight_ itself is no guarantee of clarity. In fact, _midnight on July 13_ means both "midnight, the night of July 12-13" and "midnight, the night of July 13-14." Is there a consensus on which meaning is correct? Even if usage is strongly in favor of one over the other, surely there is even a _stronger_ consensus that _12 PM on July 13_ means "noon of July 13."


 

I was going to write "balderdash!" but instead I will write, "I don't think there is any possibility of confusion when using the word 'midnight'".

For example:

If I were to say, "Meet me at Midnight on Friday."  You will know with certainty that 60 seconds after you meet me it will be 12:01 on Saturday morning.

Similarly, if I were to say, "Meet me on July 13th at midnight."  You will know with certainty that 60 seconds after you meet me it will be 12:01 on the morning of the 14th.

No confusion at all.


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## panjandrum

In another context completely I have recently noted that 8:31pm occurs long after 12:38pm.
What a strange world we live in.


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## Packard

panjandrum said:


> In another context completely I have recently noted that 8:31pm occurs long after 12:38pm.
> What a strange world we live in.


 

???


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## mplsray

Packard said:


> Originally Posted by *panjandrum*
> "In another context completely I have recently noted that 8:31pm occurs long after 12:38pm.
> "What a strange world we live in."
> 
> 
> ???


 
To translate: 2031 hours occurs long after 1238 hours.

Of course, *panjandrum*'s point is lost in the translation.


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## panjandrum

mplsray said:


> To translate: 2031 hours occurs long after 1238 hours.
> 
> Of course, *panjandrum*'s point is lost in the translation.


Thank you.  Exit panj, bowing, scraping and doffing feather-plumed hat.


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## mplsray

Packard said:


> I was going to write "balderdash!" but instead I will write, "I don't think there is any possibility of confusion when using the word 'midnight'".
> 
> For example:
> 
> If I were to say, "Meet me at Midnight on Friday." You will know with certainty that 60 seconds after you meet me it will be 12:01 on Saturday morning.
> 
> Similarly, if I were to say, "Meet me on July 13th at midnight." You will know with certainty that 60 seconds after you meet me it will be 12:01 on the morning of the 14th.
> 
> No confusion at all.


 
From the faq of the newsgroup sci.astro:

"In general, the old English A.M./P.M. notation is extremely problematic. A shorter and more obvious time notation is the modern 24h notation in which the hours in the day range from 00:00 to 23:59. This notation even allows one to distinguish midnight at the start of the day [00:00] from midnight at the end of the day [24:00], while the old English notation requires kludges like starting a contract at 12:01 A.M. in order to make clear which of the two midnights associated with a date had been intended."


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## Sepia

If you take a closer look at the real meaning of the letters AM or PM you all ought to notice that there is no way that "12am" can make any logical sense. 12pm would mathematically make sense but why use it when "12am" can't be used (logically)?


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## Packard

mplsray said:


> To translate: 2031 hours occurs long after 1238 hours.
> 
> Of course, *panjandrum*'s point is lost in the translation.


 
He is mixing 12 hour clocks with 24 hour clocks.  You cannot do that; you end up with gibberish.

There is an old math game you can play with small children.  It goes like this:

Adult:  How many fingers do you have?

Child:  10

Adult:  Count them.

Child:  1, 2, 3, 4, 5; 6, 7, 8, 9, 10.

Adult:  Count down the numbers on your right hand.

Child:  10, 9, 8, 7, 6,

Adult:  OK.  So you have "6" on your right hand, and how many do you have on your left hand.

Child:  5

Adult:  OK, 5 + 6 = 11; you have 11 fingers


The point being that you cannot mix addition and subtraction in the same equation like this.  You end up with gibberish.

The same is happening when you mix 24 hour clocks and 12 hour clocks.  Gibberish.


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## mplsray

Sepia said:


> If you take a closer look at the real meaning of the letters AM or PM you all ought to notice that there is no way that "12am" can make any logical sense. 12pm would mathematically make sense but why use it when "12am" can't be used (logically)?


 
The trouble with that argument is the phrase "real meaning." It makes sense in this context only if you are arguing that the real (that is, "true") meaning of a word or expression arises from its etymology, and if you do that you become guilty of the etymological fallacy (a logical fallacy which is a subset of the genetic fallacy).


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## Packard

Wow.  Does anyone know what time it is?


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## panjandrum

panjandrum said:


> In another context completely I have recently noted that 8:31pm occurs long after 12:38pm.
> What a strange world we live in.





Packard said:


> He is mixing 12 hour clocks with 24 hour clocks.  You cannot do that; you end up with gibberish.
> 
> [...]
> 
> The point being that you cannot mix addition and subtraction in the same equation like this.  You end up with gibberish.
> 
> The same is happening when you mix 24 hour clocks and 12 hour clocks.  Gibberish.


I wasn't mixing anything, I was quoting from another thread.   There is an example in this  thread - if you happen to be living in the GMT+1 time zone. 
I look at the time of Packard's post, 2:32 AM.
Then I look at the time of the post immediately before it, Sepia's post - 12:47 AM.
Yes, in this strange scheme 12:47 comes before 2:32.
I'm not complaining, only supporting the point of view that it is not always possible to apply mathematics to language.


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## roxcyn

11:59 PM ---->  12:00 AM.  If you use an alarm clock, you must put it as AM.  Also my computer says it as AM as well.  I am sure it has gone back to tradition.  During this time people where asleep and it was considered "night" time, so AM time.  

11:59 AM ----> 12:00 PM.  Again, it is the similar explanation above.  People consider the "morning" time has not gone, and it's time for the rest of the day.

You may want to use the 24 hour system, if you are confused.  12:00 (Twelve hundred hours) or 00:00/24:00 (oh hundred hours / twenty-four hundred hours).


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## mally pense

I have to say that as a native English speaker, I get totally confused by references to 12:15am or pm. I've never any idea which one is which.


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## roxcyn

mally pense said:


> I have to say that as a native English speaker, I get totally confused by references to 12:15am or pm. I've never any idea which one is which.



I explained which was which .  

12:15 AM = 00/24:15
12:15 PM = 12:15


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## mally pense

Yes, I know, but next time the issue arises I will have forgotten yet again. Quarter past midnight I'm happy with, ditto 12:15 meaning just after mid-day, but to me 12:15 AM just doesn't sit comfortably in my brain for just after midnight. No amount of explaining will change that.


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## mplsray

mally pense said:


> Yes, I know, but next time the issue arises I will have forgotten yet again. Quarter past midnight I'm happy with, ditto 12:15 meaning just after mid-day, but to me 12:15 AM just doesn't sit comfortably in my brain for just after midnight. No amount of explaining will change that.



It's worth pointing out that there is no controversy concerning 12:01 AM to 12:59 AM, which is why 12:01 AM is used in contracts instead of 12:00 AM to indicated when a contract provision takes effect at the beginning of a given date.


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## mally pense

> It's worth pointing out that there is no controversy concerning 12:01 AM to 12:59 AM, which is why 12:01 AM is used in contracts instead of 12:00 AM to indicated when a contract provision takes effect at the beginning of a given date.


 
I'm sure it _is_ worth pointing this out, but perhaps not all that apposite to quote me in doing so because contractual clarity or ambiguity isn't something that is an issue for my brain when working at this everyday human level of day-to-day thought or conversation. Your point doesn't really follow on from mine in this respect.

No, I think the biggest issue my brain has is in the concept that somehow 12 hours can be considered to have been counted or to have passed at the very start of the day when in fact not even a single hour has passed. (Which is why my brain doesn't have such a problem with 12:15 _(am or pm, or no qualifier, no matter)_ being used to represent a time just after noon. In that instance my brain is aware that roughly 12 hours and some _have_ passed since the start of the day.

I'm saying "my brain", because at this level, I'm not thinking consciously or intellectually, I'm just engaged in basic human interaction, and intellectually I'm pretty much an observer looking on at my brain's "gut reaction" _(if that's not too much a contradiction in terms)_. Contracts, timetables and such can certainly find use in distinguishing times and dates by establishing intellectual conventions and avoiding specific times to circumvent ambiguity, but at the human level, it's nice to be able to refer to these times simply as midnight and noon with absolutely no ambiguity whatsoever _(as Packard will no doubt agree)_ . 

By the way, are legal contracts forbidden to use "midnight" and "noon"? I wasn't aware of such a restriction.



> But here is what has always bothered me about am and pm: If 3 am is 3 hours ante-meridiem, shouldn't that mean 3 hours before noon (what we call 9 o'clock in the morning)?


 
Just to pick up on this earlier point: am and pm aren't used as a _count_ forwards or backwards from noon; they're used to indicate one of two halves of the day, i.e. the half that occurs before noon or the half that occurs after noon. 3am is not "three hours before noon", but "three hours after midnight in the _'before noon'_ half of the day".


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## Sepia

mally pense said:


> Yes, I know, but next time the issue arises I will have forgotten yet again. Quarter past midnight I'm happy with, ditto 12:15 meaning just after mid-day, but to me 12:15 AM just doesn't sit comfortably in my brain for just after midnight. No amount of explaining will change that.




That is just about what I was pointing out further up.

AM meaning Ante Meridiem = before mid-day could makes no logical sense with a time referring to mid-day.

Noon is neither AM nor PM, when AM and PM mean before and after Noon. 
12 hours before or after Noon would both be Midnight.

However, 15 Min after Midnight is definitely AM because within its 24 hour period it is before Noon.


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## mally pense

> ...when AM and PM mean before and after Noon...


 
Well they do and they don't mean this. Yes they do in the sense the that first half of the day is before noon and the second half of the day is after noon, but they're certainly not used in the sense of noon providing a reference point for counting hours before or after. No more so in fact than "afternoon" is used as a counting reference, which is why we say "I'll see you _this_ afternoon" or "I'll be there _in the_ afternoon" and not "I'll be there three hours _afternoon_" (sic).

AM and PM are used in this way too, i.e. to refer to periods of time (with 12 hours in each) rather than as some sort of continuous temporal metric. Hence, regardless of my concerns for the basic human level of comprehension (or otherwise) of 12 am/pm, "12am" does NOT mean twelve hours before noon, it means twelve o'clock in the before-noon half of the day (even if it arguably happens to give the same result in this specific instance).


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## Sepia

mally pense said:


> Well they do and they don't mean this. Yes they do in the sense the that first half of the day is before noon and the second half of the day is after noon, but they're certainly not used in the sense of noon providing a reference point for counting hours before or after. No more so in fact than "afternoon" is used as a counting reference, which is why we say "I'll see you _this_ afternoon" or "I'll be there _in the_ afternoon". AM and PM are used in this way too, i.e. to refer to periods of time (with 12 hours in each) rather than as some sort of temporal metric. Hence, regardless of my concerns for the basic human level of comprehension or otherwise of 12 am/pm, "12am" does NOT mean twelve hours before noon, it means twelve o'clock in the before-noon half of the day (even if it happens to give the same result in this specific instance).




Yes, sure, but this logic still supports your argument and other people's argument for using Noon and Midnight, doesn't it?


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## expenseroso

Hmm... I've seen 12:00 AM and 12:00 PM used quite a bit. Although, if it isn't immediately clear from the context, it still takes a second for me to process, I'd never think of either as being incorrect. Noon and midnight are certainly preferable if you want to increase the fluency with which your writing/speech is understood (and why wouldn't you?).


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## mally pense

> Yes, sure, but this logic still supports your argument and other people's argument for using Noon and Midnight, doesn't it?


 
Yes, though I'm really not arguing a case proactively. Like expenseroso, I'm just saying that it doesn't sit comfortably with my brain, or as he puts it more specifically, it still takes a second or so to process and neither of them will ever be thought of as correct. But as long as the people I know continue to use language such as "I got in just after midnight" in real life I'll be happy.


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## JulianStuart

Forero said:


> But here is what has always bothered me about am and pm:  If 3 am is 3 hours ante-meridiem, shouldn't that mean 3 hours before noon (what we call 9 o'clock in the morning)?



 I was confused by that until I realized that the am or pm part of a time just tells you which 12hour interval is being used for the clock face.  It doesn't mean 3 hours before meridian (like I thought) it means 3 o'clock when the clock is showing the 12 hours before midday (I'm sorry, before noon  )  Or "It's 3 hours since the clock face went from displaying pm to displaying am"

Now, for the pm 12 hrs clock face, the numbers do actually match the number of hours post midday  noon

Let's not think about 3 am meaning 3 hours* A*fter *M*idnight


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## Rover_KE

marget said:


> Hi,
> 
> Can anyone explain why we say PM for noon when it's exactly, not after, noon?



The precise instant of noon only lasts for a nanosecond (or probably less than that).

We have no time to register this moment before it's already after noon (PM).

Rover


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## Peter Tran

As we know that the time between midnight and noon, we have to say a.m after the time such as 3 a.m, 7 a.m etc... and from noon till midnight it should be p.m following the time such as 1 p.m, 10 p.m. But why at 12 o'clock at noon, it becomes 12 p.m and 12 o'clock at midnight -it's called 12 a.m. Please particularly explain that to me. It makes me get confused.

Mod note: Peter's thread is now merged with an earlier thread.


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## Egmont

We say 12:00 a.m. for midnight to be consistent with 12:01 a.m., 12:02 a.m., and so on through 12:59 a.m. It's the same for p.m.

People who want to be certain of avoiding confusion will say "12 noon," often abbreviated 12n, or "12 midnight," which can be abbreviated as 12m - or they use a 24-hour clock.


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## Hau Ruck

There is neither a 12 a.m. nor a 12 p.m. 
There is only 12 noon and 12 midnight.

12:01 a.m./p.m. is possible, as is any of the other 58 minute markers.

a.m. actually stands for Ante Meridiem (before noon) and p.m. stands for Post Meridiem (after noon).

_*12:00*_ a.m./p.m. is never a real _thing_.


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## Copperknickers

Sorry Filsmith but you are incorrect. 12.00 a.m. is always understood to be midnight, and 12.00 p.m. is always understood to be midday. Look on any clock which differentiates between them. 

The reason is obvious: 12.00 a.m. is officially the start of the new day, so there hasn't been a noon yet, hence it is before noon. 12.00 p.m. therefore is after noon (technically it should be 12.00 m. and then 12.01 p.m etc. but that is overcomplicating things).


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## Hau Ruck

Copperknickers said:


> Sorry Filsmith but you are incorrect. 12.00 a.m. is always understood to be midnight, and 12.00 p.m. is always understood to be midday. Look on any clock which differentiates between them.
> 
> The reason is obvious: 12.00 a.m. is officially the start of the new day, so there hasn't been a noon yet, hence it is before noon. 12.00 p.m. therefore is after noon (technically it should be 12.00 m. and then 12.01 p.m etc. but that is overcomplicating things).



No, I'm sorry, but that is not correct.  By the very definition of Ante Meridiem and Post Meridiem, there is no such thing as 12:00 a.m. or 12:00 p.m.  There is a 12:01 a.m./p.m., 12:02 a.m./p.m., 12:03 a.m./p.m., 12:04 a.m./p.m., etc.   It is impossible to have an actual 12:00 a.m. or 12:00 p.m.   

I can assure you that this topic is quite heavily covered out there in the world of google.


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## Copperknickers

Filsmith said:


> No, I'm sorry, but that is not correct.  By the very definition of Ante Meridiem and Post Meridiem, there is no such thing as 12:00 a.m. or 12:00 p.m.  There is a 12:01 a.m./p.m., 12:02 a.m./p.m., 12:03 a.m./p.m., 12:04 a.m./p.m., etc.   It is impossible to have an actual 12:00 a.m. or 12:00 p.m.
> 
> I can assure you that this topic is quite heavily covered out there in the world of google.



I don't know the technicalities of it, but this forum is for language, not metaphysics. No amount of googling can take away from the fact that 90% of English speakers know that 12.00 a.m. is midnight and 12.00 p.m. is midday. Nor can it take away from the fact that 12.00 a.m. comes before 12 noon on any given day.


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## Andygc

Copperknickers said:


> the fact that 90% of English speakers know that 12.00 a.m. is midnight and 12.00 p.m. is midday.


Do you have any evidence to support that _fact_? I am happy to be in the alleged 10% that has never thought that midnight and midday could be described as 12 am and 12 pm. I am fascinated by the metaphysical and existential conundrum posed by 12 pm trying to be both itself and after itself at the same time. This ranks with questions such as "Is Time a Mobius Strip?" and "The answer is 42, but what is the question?"


----------



## Packard

Copperknickers said:


> ...No amount of googling can take away from the fact that 90% of English speakers know that 12.00 a.m. is midnight and 12.00 p.m. is midday. Nor can it take away from the fact that 12.00 a.m. comes before 12 noon on any given day.



Count me amongst the 10% who live in the dark.  I can never get it clear in my mind if a.m. means noon or midnight.

(I also confuse "top up/top down" in convertible automobiles--so this may be more to do with the way my mind works that language.)


----------



## Einstein

Isn't it time the English-speaking world adopted the 24-hour clock for travel purposes, like everyone else? It would save a lot of trouble.


----------



## mplsray

Filsmith said:


> No, I'm sorry, but that is not correct.  By the very definition of Ante Meridiem and Post Meridiem, there is no such thing as 12:00 a.m. or 12:00 p.m.




As mentioned previously in this thread (Post #27), that argument is an example of the etymological fallacy.


----------



## Hau Ruck

mplsray said:


> As mentioned previously in this thread (Post #27), that argument is an example of the etymological fallacy.



I'm not sure why you think this is false etymology?  a.m. and p.m. are not debatable in their meaning nor their origin.  Am I missing something?


----------



## Sedoso

foxfirebrand said:


> We could look at 12N and 12M as ambiguously AM or PM, and be scrupulously mathematical about it forever-- but those of us who have to get on with the business of telling or keeping time have to pick one or the other to assign to each, and that's where convention gets imposed.  It's the same case with idiom, which is of course never logical-- it's just the way we say/do it, the way things have sorted out.



I suggest we all switch to military time.  Noon is 1200 hrs and midnig

AM= Antimeredian
PM= Past meridian

it's noon when come written PM
and AM when it's morning


----------



## Forero

mplsray said:


> As mentioned previously in this thread (Post #27), that argument is an example of the etymological fallacy.


I'll add to this that most of us have no trouble understanding that 3h a.m. is 3 hours after "midnight", whenever that is, not 3 hours before midday.

A.M. refers to the twelve hours beginning at "midnight" and ending at "noon". Unfortunately, the Romans did not "know about" the number zero, so instead of 00:00 through 00:59 they called the first hour 12:00 through 12:59, which puts the twelves, all of them, before one o'clock instead of after the elevens.

I don't know if this makes sense, but this is how I can (finally) remember the "convention".

Also unfortunately, because of how we set our clocks, midday today where I live is after 1 pm— and I still have trouble with what century was the 17th.


----------



## sdgraham

Peter

Given the above lack of unanimity, you probably see by now that good writers and speakers don't say 12:00 a.m. or p.m., but specify 12 noon or 12 midnight, if, in fact, don't just drop the 12:00 altogether and say "noon" or "midnight.
Others, such as some of the major U.S. air carriers, just publish their schedules based upon the 24-hour clock.

.


----------



## mplsray

Filsmith said:


> I'm not sure why you think this is false etymology?  a.m. and p.m. are not debatable in their meaning nor their origin.  Am I missing something?



It's not a question of false etymology but of a logical fallacy. The meaning of a word is not determined by its origin but by its usage. Noon is 12 PM and midnight is 12 AM in actual usage.

This usage was once confined to technical language--the oldest use of P.M. for noon which I have found so far was in an 1835 book on meteorology--but the digital clock has brought it into everyday use.


----------



## Hau Ruck

mplsray said:


> It's not a question of false etymology but of a logical fallacy. The meaning of a word is not determined by its origin but by its usage. Noon is 12 PM and midnight is 12 AM in actual usage.
> 
> This usage was once confined to technical language--the oldest use of P.M. for noon which I have found so far was in an 1835 book on meteorology--but the digital clock has brought it into everyday use.




Many things are in usage but not correct; moderate _usage_ doesn't dictate correctness.  Ain't, nuthin', Day Light Saving*'s* Time, Old Timer's Disease, alot, etc. are used all-too-commonly.  Just because a majority of people don't understand there is no such _thing_ as 12 a.m. / p.m., doesn't mean that they aren't wrong. We should not further propagate such incorrect usage here, or anywhere.  This is not a matter of how something has evolved into somehow being correct; it's just not correct.  
90%+ people say "Daylight Saving*'s* Time".  That's _not_ correct.  Just because a majority think it correct, does it make it so? No, it does not.

There is not, nor has there ever been a 12 a.m. / 12 p.m.    Just because people don't know any better is no reason to give it validity in _any _sort of context.


----------



## mplsray

Filsmith said:


> Many things are in usage but not correct; moderate _usage_ doesn't dictate correctness.  Ain't, nuthin', Day Light Saving*'s* Time, Old Timer's Disease, alot, etc. are used all-too-commonly.  Just because a majority of people don't understand there is no such _thing_ as 12 a.m. / p.m., doesn't mean that they aren't wrong. We should not further propagate such incorrect usage here, or anywhere.  This is not a matter of how something has evolved into somehow being correct; it's just not correct.
> 90%+ people say "Daylight Saving*'s* Time".  That's _not_ correct.  Just because a majority think it correct, does it make it so? No, it does not.
> 
> There is not, nor has there ever been a 12 a.m. / 12 p.m.    Just because people don't know any better is no reason to give it validity in _any _sort of context.



From a linguistic point of view, since 12 AM and 12 PM are used by educated speakers of the English language, they are standard English, unlike _ain't_, which is used by standard speakers only when imitating nonstandard usage.

Since insisting that "12 AM has never meant 12 midnight" is an example of the etymological fallacy, it is just plain wrong. Logical fallacies should be avoided.


----------



## Keith Bradford

I'm in complete agreement with SDGraham here (#56), the trouble with this discussion is that we're asking the wrong question. Like "How many sides has a square triangle?"

The ONLY sensible question to ask is: "How should an intelligent native speaker express the concepts of noon and midnight, in order to be perfectly understood?" All other questions are based on stupidity, or on false expectations of what others will take as conventional (Filsmith _et al_).

My answer:
In everyday speech and non-technical writing: *noon *(or *midday*)* and midnight*.
In technical speech and writing: *12.00 and 24.00 *(pronounced twelve hundred hours/twenty-four hundred hours, (though the BBC shipping forecast pronounces _one two hundred_ etc).


----------



## Hau Ruck

mplsray said:


> From a linguistic point of view, since 12 AM and 12 PM are used by educated speakers of the English language, they are standard English, unlike _ain't_, which is used by standard speakers only when imitating nonstandard usage.
> 
> Since insisting that "12 AM has never meant 12 midnight" is an example of the etymological fallacy, it is just plain wrong. Logical fallacies should be avoided.



_Day Light Saving*'s* Time_ is most commonly said by educated English speakers as well. Should we go ahead and tell people it's fine to misuse that term as well?
Many educated English speakers spell a lot as "alot", should we let that pass?
Where I live, there is a grocery chain called "Kroger".  95% of the people here incorrectly refer to it as "Kroger*s*".  They are neither referring to multiple Kroger nor any possessive form of the word. If 95% of the people refer to it in such a way, should we just rename the store? No. 

Bottom line, no matter how much widespread misuse of a word/term is in place, it does not make that word/term correct.

12 a.m./p.m. _never_ = 12 midnight/noon.  Ever.  Not in reality, not in physical space, and not in linguistics.  It only _exists_ that way in widespread misuse across educated, uneducated, native and non-native speakers alike.  It is our responsibility here to teach non-native (and even native) speakers the _correct_ way.  

There is no real debate there.  It's not correct.  You can pretend that etymological fallacy somehow lends legitimacy to this misuse; it really does not.

Etymological fallacy refer to words/phrases that _everyone_ accepts.  There are plenty of people here that don't think 12 a.m. / p.m. is a real way to express 12 midnight/noon.  The same cannot be said for _knight, hound, lady_ and other words that had different meanings in Old English or other languages we borrowed the terms from.  No one will try to argue that _knight _somehow means _servant  _in today's usage.  No debate.  The same cannot be said for the subject at hand.  It is not etymological fallacy when so many are not accepting of its use.


----------



## Ironicus

For humans,_ noon_ and _midnight_ are perfect. Who could mistake them?
For machines, _12:00_ and _24:00_ are extremely handy for arithmetic, and for rational notation. How the machines say the numbers is a matter for the programmers: good ones will make them say 'noon' and 'midnight' when talking to humans.
Incidentally, if we want to be pedantic, we should not call 12:00 _twelve hundred_: that's not a hundred, it's a zero on a scale that turns over at 59, not 99.


----------



## sdgraham

Ironicus said:


> For humans,_ noon_ and _midnight_ are perfect. Who could mistake them?
> For machines, _12:00_ and _24:00_ are extremely handy for arithmetic, and for rational notation. How the machines say the numbers is a matter for the programmers: good ones will make them say 'noon' and 'midnight' when talking to humans.
> Incidentally, if we want to be pedantic, we should not call 12:00 _twelve hundred_: that's not a hundred, it's a zero on a scale that turns over at 59, not 99.


The fourth sentence shows that the second is not entirely correct. There's nothing simple about arithmetic where time and date is concerned.


----------



## Keith Bradford

Ironicus said:


> ... Incidentally, if we want to be pedantic, we should not call 12:00 _twelve hundred_...



But who wants to be pedantic?  I just want to be understood.  That's why I agree with the beginning of your answer.


----------



## Forero

Ironicus said:


> For humans,_ noon_ and _midnight_ are perfect. Who could mistake them?


I have heard people recommend staying out of the sun "within two hours of noon", and this advice only makes sense if _noon_ refers to the time the sun is highest in the sky, usually close to 1 "P.M.", not 12.

In this reckoning, it would be more logical to call twelve o'clock in the day time, 12 A.M. since it is obviously before midday during most of the year because our clocks are advanced an hour from the mean sun.

If the intent is to be understood, "12:00 P.M." for twelve o'clock in the day time is certainly confusing. Would everyone understand "12h CDT"?


> For machines, _12:00_ and _24:00_ are extremely handy for arithmetic, and for rational notation. How the machines say the numbers is a matter for the programmers: good ones will make them say 'noon' and 'midnight' when talking to humans.
> Incidentally, if we want to be pedantic, we should not call 12:00 _twelve hundred_: that's not a hundred, it's a zero on a scale that turns over at 59, not 99.


I agree that 12:00 is meant to be twelve sixties of minutes, certainly not twelve hundred hours.


----------



## Andygc

Forero said:


> I have heard people recommend staying out of the sun "within two hours of noon", and this advice only makes sense if _noon_ refers to the time the sun is highest in the sky, usually close to 1 "P.M.", not 12.


Isn't this thread wandering a bit? Noon is when the sun is at its zenith. That is 12:00 local time (I am using 24-hour notation in this case). It is not particularly likely to coincide exactly with 12 noon by time zone time (in most time zones a possible error of about ± 30 minutes) and will be approximately 13:00 by daylight saving time. This, of course, makes no difference whatsoever to whether we chose to call it 12 pm or 12 noon.

Or, for that matter, any difference to the price of fish


----------



## mplsray

Filsmith said:


> _Day Light Saving*'s* Time_ is most commonly said by educated English speakers as well. Should we go ahead and tell people it's fine to misuse that term as well?
> Many educated English speakers spell a lot as "alot", should we let that pass?
> Where I live, there is a grocery chain called "Kroger".  95% of the people here incorrectly refer to it as "Kroger*s*".  They are neither referring to multiple Kroger nor any possessive form of the word. If 95% of the people refer to it in such a way, should we just rename the store? No.
> 
> Bottom line, no matter how much widespread misuse of a word/term is in place, it does not make that word/term correct.
> 
> 12 a.m./p.m. _never_ = 12 midnight/noon.  Ever.  Not in reality, not in physical space, and not in linguistics.  It only _exists_ that way in widespread misuse across educated, uneducated, native and non-native speakers alike.  It is our responsibility here to teach non-native (and even native) speakers the _correct_ way.
> 
> There is no real debate there.  It's not correct.  You can pretend that etymological fallacy somehow lends legitimacy to this misuse; it really does not.
> 
> Etymological fallacy refer to words/phrases that _everyone_ accepts.  There are plenty of people here that don't think 12 a.m. / p.m. is a real way to express 12 midnight/noon.  The same cannot be said for _knight, hound, lady_ and other words that had different meanings in Old English or other languages we borrowed the terms from.  No one will try to argue that _knight _somehow means _servant  _in today's usage.  No debate.  The same cannot be said for the subject at hand.  It is not etymological fallacy when so many are not accepting of its use.



You appear to entirely miss the point of the etymological fallacy. It is the belief that the etymology of a word determines the meaning of that word, while instead it is usage that determines that meaning. The meaning of the Latin _ante meridiem_ and _post meridiem_ are irrelevant to the meaning of AM and PM. (They might be _useful,_ since they serve as a mnemonic, but that's not the same as determining meaning.)

Proper names operate by different rules, as do legal terms. Kroger is a proper name and a legal term (a trademark) and Daylight Saving Time appears to be both a proper name and a legal term. In such cases, you can indeed make an argument that the common usage is incorrect. In the case of _alot_, not enough standard speakers use it. If they did, it would become standard, just as _today_ is now standard and _to-day_ is not. To state that "12 AM does not mean 12 midnight" is proven to be evidently false by the linguistic evidence.

(A side point: Because of standardized time, 11:59 AM and 12:01 PM at a given spot on the globe most often take place either both _ante meridiem_, in the strictest Latin and astronomical sense, or both _post meridiem_ Why would you swallow this elephant and then to strain at the gnat of 12 PM equaling noon?)


----------



## sdgraham

Just to stir the pot, what time is meant when somebody tells you "the train leaves at 'ten minutes to 12 p.m.?' "


----------



## Hau Ruck

sdgraham said:


> Just to stir the pot, what time is meant when somebody tells you "the train leaves at 'ten minutes to 12 p.m.?' "



Exactly.  It would not be very clear to do so. "Ten minutes to noon" would be much clearer.



> You appear to entirely miss the point of the etymological fallacy.


I'm not missing the point, I just don't agree with you. 



> To state that "12 AM does not mean 12 midnight" is proven to be evidently false by the linguistic evidence.


_Proven _is a strong word; nothing of the sort has been _proven._

I'm really not seeing why you do not _believe_ that a.m. is short for _ante meridiem_ and p.m. short for _post meridiem_.  I've never seen anything to suggest that they are not true abbreviations of each. 
To say that 12 a.m. does not mean 12 midnight _is_ false.  I, like most of the English speaking world, am accepting that a.m. is short for _ante meridiem_.  After, cannot, by its very definition, be during or before; it is _after.  _12 midnight is not after; it is during.  
If you are truly saying you do not believe a.m. is short for _ante meridiem_, then with that line of thinking, you can consider your argument valid.  However, I've seen nothing that would indicate such a thing.


----------



## kalamazoo

Somebody once won his court case (in NY?) based on the ambiguity in a parking sign that read 12 PM. I got involved in this issue years ago having to with a questionnaire we had administered in which people reported the time at which they last ate.  It ws a problem if they had fasted too many hours.  There were obviously many many people using the times differently. They might say that they had last eaten before 12 PM but their dietary records showed that they had eaten dinner in the evening. Or vice versa.   I have to agree, either use military time or else specify noon or midnight.  12 PM is simply ambiguous.  Some people are sure about it, but not everybody agrees. (And of course for Latin scholars it makes no sense to call noon AM or PM, it obviously is M.)


----------



## mplsray

kalamazoo said:


> Somebody once won his court case (in NY?) based on the ambiguity in a parking sign that read 12 PM. I got involved in this issue years ago having to with a questionnaire we had administered in which people reported the time at which they last ate.  It ws a problem if they had fasted too many hours.  There were obviously many many people using the times differently. They might say that they had last eaten before 12 PM but their dietary records showed that they had eaten dinner in the evening. Or vice versa.   I have to agree, either use military time or else specify noon or midnight.  12 PM is simply ambiguous.  Some people are sure about it, but not everybody agrees. (And of course for Latin scholars it makes no sense to call noon AM or PM, it obviously is M.)



I maintain that the court case in question does not decide the matter. For many years, the US federal government did not accept that _white chocolate_ could be listed as an ingredient in the packaging of food products. Later, it decided that it was acceptable. During all this time, standard speakers of American English happily used the term _white chocolate_. It seems absurd to me to say that it was incorrect in standard speech and writing during the time when the government did not allow it and correct during those times when the government allowed it--with the exception of _those marketing and ingredient-list__ uses_[1]_ forbidden by law_, which were arguably incorrect.

What the court case dealt with was 12 PM as a technical term (in this case, a legal term), _in a limited circumstance and under one particular legal jurisdiction,_ with a high probability that in other court cases in other circumstances and legal jurisdictions the decision went the other way.

Note: That's "ingredient-list uses" placed by the producer of the product on packaging and in advertising. Cookbook recipes, cooking shows, and ordinary people engaged in talking about food were never forced to comply.


----------



## mplsray

Filsmith said:


> Exactly.  It would not be very clear to do so. "Ten minutes to noon" would be much clearer.
> 
> 
> I'm not missing the point, I just don't agree with you.
> 
> 
> _Proven _is a strong word; nothing of the sort has been _proven._
> 
> I'm really not seeing why you do not _believe_ that a.m. is short for _ante meridiem_ and p.m. short for _post meridiem_.  I've never seen anything to suggest that they are not true abbreviations of each.



I have at no point suggested that AM is not short for _ante meridiem,_ nor have I ever suggested that PM is not short for _post meridiem_. I find it baffling that you think that I might have done such a thing.

I did make the point that because of standard time, our AM and PM do not correspond with the ancients' ideas about what _ante meridiem_ and _post meridiem_ meant. All you have to do is to look up at the position of the sun in your area at 11:59 AM to verify this--Most of the time, in most places on earth, the sun is not be where an astute ancient would have expected it to be if you were to tell him it would shortly be noon[1]. (And more ancients were astute about such things than are modern people, because we don't pay as much attention to events in the sky as they did.)

Note: [1] The English term _noon_ being used here as a substitute for whatever term the ancient in question would have given for the moment when the sun is at its highest point in the sky on a given day. The sun would not be there between 11:59 AM and 12:01 PM, in the vast majority of cases when this experiment was done.


----------



## Andygc

mplsray said:


> Note: [1] The English term _noon_ being used here as a substitute for whatever term the ancient in question would have given for the moment when the sun is at its highest point in the sky on a given day. The sun would not be there between 11:59 AM and 12:01 PM, in the vast majority of cases when this experiment was done.


I see. Perhaps what you meant to write was:

"As Andygc so succinctly put it in post #66


> Noon is when the sun is at its zenith. That is 12:00 local time (I am  using 24-hour notation in this case). It is not particularly likely to  coincide exactly with 12 noon by time zone time (in most time zones a  possible error of about ± 30 minutes) and will be approximately 13:00 by  daylight saving time. This, of course, makes no difference whatsoever  to whether we chose to call it 12 pm or 12 noon.


"


----------



## wandle

I follow three rules on this.
(1) Never use the expressions '12 am' or '12 pm' on your own account. 
(2) Only use the expressions '12 noon' (or 'midday') and '12 midnight' on your own account (or omit the '12').
(3) When someone else uses '12 am' or '12 pm', unless it is completely clear from the context, enquire whether they mean noon or midnight.


----------



## kalamazoo

I think wandle's rules are excellent. There actually are a number of court cases in the US involving the question of what is meant by 12 am or 12 pm on signs or in laws. One I read was about a Florida case involving a law that about selling cocaine near a school, which was subject to higher penalities if done betwen 6 AM and "12 AM".  The court did decide that this was vague and clear evidence was introduced to show that the terms were used in different ways (including a photograph of a sign at the local jail about visiting hours from "8 am to 11 am" and  "12 am to 4:30 PM").  This was actually based on evidence,not just on some individual opinion that it was obvious, and the court decided that people of normal intelligence could not necessarily know what was meant.


----------



## Keith Bradford

wandle said:


> I follow three rules on this.
> (1) Never use the expressions '12 am' or '12 pm' on your own account.
> (2) Only use the expressions '12 noon' (or 'midday') and '12 midnight' on your own account (or omit the '12').
> (3) When someone else uses '12 am' or '12 pm', unless it is completely clear from the context, enquire whether they mean noon or midnight.



Brilliant!  

Can I suggest a fourth?  
(4)  Don't accept their answer as being binding on anyone except them.


----------



## RM1(SS)

Having been pointed here by a closed thread, I thought I'd add to the confusion. 8)

"2:00 AM" is the "two o'clock" which occurs "ante meridiem," meaning "before noon."  It is preceded by "1:00 AM," which is the "one o'clock" which occurs before noon, and that in turn is preceded by "12:00 AM," which is the "12 o'clock" which occurs before noon.  So "12:00 AM" is quite obviously midnight.

"10:00 PM" is the "ten o'clock" which occurs "post meridiem," meaning "after noon."  It is followed by "11:00 PM," which is the "eleven o'clock" which occurs after noon, and that in turn is followed by "12:00 PM," which is the "12 o'clock" which occurs after noon.  So "12:00 PM" is quite obviously midnight.

And noon is equally obviously neither before nor after itself, so noon is neither "12:00 AM" nor "12:00 PM."


And if it's not obvious: Yes, I am saying that "12:00 PM Tuesday" and "12:00 AM Wednesday" are the exact same time.


----------



## natkretep

Very clever RM1! But I suppose someone could claim that the extent of the 'before' and 'after' cannot be more than 11 hours 59 minutes! 

For the sake of completeness, I thought I should say that Wikipedia has a nice summarising section about the confusion in their article about the 12-hour clock.


> It is not always clear what times "12:00 a.m." and "12:00 p.m." denote. From the Latin words _meridies _(midday),_ ante _(before) and_ post _(after), the term_ ante meridiem_ (a.m.) means before midday and_ post meridiem_(p.m.) means after midday. Since strictly speaking "noon" (midday) is neither before nor after itself, the terms a.m. and p.m. do not apply. However, since 12:01 p.m. is after noon, it is common to extend this usage for 12:00 p.m. to denote noon. That leaves 12:00 a.m. to be used for midnight at the beginning of the day, continuing to 12:01 a.m. that same day_._[and more]


----------



## RM1(SS)

natkretep said:


> Very clever RM1! But I suppose someone could claim that the extent of the 'before' and 'after' cannot be more than 11 hours 59 minutes!



It's the first "X o'clock" you reach when you begin at noon and move in either the "before" or the "after" direction (as appropriate).


----------



## Hau Ruck

RM1(SS) said:


> Having been pointed here by a closed thread, I thought I'd add to the confusion. 8)
> 
> "2:00 AM" is the "two o'clock" which occurs "ante meridiem," meaning "before noon."  It is preceded by "1:00 AM," which is the "one o'clock" which occurs before noon, and that in turn is preceded by "12:00 AM," which is the "12 o'clock" which occurs before noon.  So "12:00 AM" is quite obviously midnight.
> 
> "10:00 PM" is the "ten o'clock" which occurs "post meridiem," meaning "after noon."  It is followed by "11:00 PM," which is the "eleven o'clock" which occurs after noon, and that in turn is followed by "12:00 PM," which is the "12 o'clock" which occurs after noon.  So "12:00 PM" is quite obviously midnight.
> 
> And noon is equally obviously neither before nor after itself, so noon is neither "12:00 AM" nor "12:00 PM."
> 
> 
> And if it's not obvious: Yes, I am saying that "12:00 PM Tuesday" and "12:00 AM Wednesday" are the exact same time.




And this confusion (which I realize you are just making light of - this comment is not in any way an affront toward you  ) is _exactly_ why there is no '12:00:00 PM / 12:00:00 AM'.  There is technically a '12:00:01 AM / 12:00:01 PM'.

But of course there is a 12 noon as well as a 12 midnight. Both of those clear up any confusion. Makes it quite simple, in my opinion.


----------



## Einstein

This is what scientists and mathematicians call a _singularity_, something at a non-existent point in space in a non-existent period (called an instant) which is not governed by the laws of the universe as we know them (and they then speculate - from outside the singularity, of course - about the suspension of the laws of thermodynamics to deduce such things as the Big Bang, cosmic strings and the rest). In this case the definitions AM and PM do not apply to the singularities of noon and midnight; no problem: whatever instrument you invent, there will always be a higher-precision one that shows it's not _exactly _twelve o'clock.

Apologies to mods if necessary


----------



## Hau Ruck

Einstein said:


> This is what scientists and mathematicians call a _singularity_, something at a non-existent point in space in a non-existent period (called an instant) which is not governed by the laws of the universe as we know them (and they then speculate - from outside the singularity, of course - about the suspension of the laws of thermodynamics to deduce such things as the Big Bang, cosmic strings and the rest). In this case the definitions AM and PM do not apply to the singularities of noon and midnight; no problem: whatever instrument you invent, there will always be a higher-precision one that shows it's not _exactly _twelve o'clock.
> 
> Apologies to mods if necessary



But along the same lines of your thinking, space and time are one, thus nothing is anything by that reasoning.    Time doesn't exist without space, nor space without time. 

The point being, we have to assign such 'things' in order to identify them as a 'point' of reference.  That's how humankind gets by.    Without such references as A.M. and P.M. (of which we are defining as a point) we have epoch anarchy!


----------



## Einstein

Hau Ruck said:


> But along the same lines of your thinking, space and time are one, thus nothing is anything by that reasoning.    Time doesn't exist without space, nor space without time.
> 
> The point being, we have to assign such 'things' in order to identify them as a 'point' of reference.  That's how humankind gets by.    Without such references as A.M. and P.M. (of which we are defining as a point) we have epoch anarchy!


OK, it wasn't a very serious comment; that's why I apologised to the mods. But as I and someone else suggested some time back, we could adopt the 24-hour clock for travel purposes and otherwise say "12 noon" and "12 midnight".


----------



## Egmont

The time designation "12 pm" is ambiguous. To me, it means noon: if 12:01 pm is in the afternoon, which it clearly is, then 12:00 pm should be one minute earlier. I think most English speakers feel the same way. A few, however, treat it as midnight, and still others say "I don't know what it means." Here, you seem to mean midnight. Be aware that you are in the minority if you use it this way. Some might even say you are wrong.


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## Parla

I agree with Egmont's comment, and I find it so confusing that I don't use "12 a.m." and "12 p.m."; I always say "12 noon" or "12 midnight", which makes the meaning clear and unambiguous.


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## RM1(SS)

To me 12 AM and 12 PM are both midnight, so I agree that specifying "noon" or "midnight," or "1200" and "2400," is much better.


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