Without wishing to appear argumentative…which is correcter?
Midnight on Saturday or Midnight on Friday. On the basis that at 11.59, ie one minute before, it is Friday 
I think technically that midnight occurs at the very beginning of a day, not at the very end. The reason I say this is that we say 00:00 and not 24:00. But it’s for this reason that I usually say “a minute past midnight on Saturday morning”, or something like that.
This hurts, but I'm going to agree with Pigfender: midnight marks the start of the day. Have you noticed that on New Year's Eve we count down to midnight as the [i]start[/i] of the new year? Not 1am, not even 12:01am, but 12:00am. :unamused:
Heck, it's even in the designation: "a.m." = "ante meridiem" = "before noon" = "morning"
Neither is correct. Midnight is not an interval of time. It is, rather, a boundary between two intervals of time that are on different days. The interval of time before it is one day and the interval of time after it is the next day. To think that midnight must be assigned to one or the other day would only make sense if midnight were itself an interval of time. But it isn’t.
(But if you don’t want to confuse people, you should say ‘at midnight on Friday’ when you mean the end of Friday.)
This is the “figurative” v “literal” debate but with time!
Isn’t context the determiner of the literal or figurative relative to “midnight” being a unit or a concept? Just like “kill” can be literal (I killed the frog when i ran over it will the car) or figurative (I killed the novel with my superman skilled writing!). When Piggy used it as “sent at midnight” didn’t it become the literal unit 00:00:00.0000? He even went so far as to qualify the unit to a specific location.
The only way I can really see midnight not being a unit is when used to refer to something “not a time”. EX midnight black, midnight silence, midnight slumber. As an adjective midnight would only be a figuration for the purposes of description.
Yes?
That sounds very sensible. The only problem being that having checked a couple of dictionaries, they all define midnight as 12 o’clock at night, and not the boundary between one day and the next.
But it SHOULD be your definition.
Sorry, but no, not really.
But I think that is not incompatible with what I said. The sources you consulted are (apparently) relying on a customary clock representation which is adequate no doubt for the practical purpose of helping someone who did not have the use of the word ‘midnight’, but which does not in any way resolve the matter.
For more on the clock representation of midnight: https://en.wikipedia.org/wiki/Midnight#Start_and_end_of_day
And for more fun:
https://en.wikipedia.org/wiki/12-hour_clock#Confusion_at_noon_and_midnight
–gr
Since you agree with my wife (that is her stock answer) then you must be right.
But I don’t see how your explanation makes it a non-unit. Please explain using words a headless man can understand.
I used to love a good philosophical debate, but these days I’m far more pragmatic: 12:00am Friday come before 12:01am Friday.
Note that the argument “there is no 12am because once a clock displays 12 the moment has passed” is specious as it applies to every single moment in time, no matter how small a unit of time one uses (1 trillionth of a second just passed? Darn! Missed it again!!).
For all pragmatic and practical purposes, 12am midnight marks the beginning of day.
But if you do it in counting terms it goes 58, 59, 60 with 60 being Midnight (Friday). The next unit (Saturday) starts at 1 then 2 etc. (regardless of whether you are counting in minutes or seconds or micro seconds or nano seconds.
ie. Friday doesn’t stop at 59 and Saturday doesn’t start at 60.
Or something…
Aprops 
I think Socrates hit the nail on the head, with this one, When he said,“Y’ wot? Wot did y’ say? Say all that again.” 
This is like any other “measurement” in a circular system (loop). The origin point is both at the same time. It is the schroadinger’s* cat of points; it exists in both states simultaneously. But relative to language, isn’t context really the driver here? Piggy clearly meant “when all the hands point straight up”. As such the point was clear and the unit measurable no matter what our political views on when the day exactly transitions from former to latter.
Yes?
*[size=60] I don’t spell my know name right, you are asking too much if you think I can even get close to his[/size]
Ahh, but, are all the hands pointing straight up on Friday or on Saturday? 
Well, I did not use the word ‘unit’ and it is unclear to me what you meant by it in what you said.
Here is me: Midnight is not an interval of time. An interval of time has some duration. It goes on for awhile. Midnight is not like that. This is what you need to see to see my point.
All of these countings are counting intervals of time. Midnight is not actually any of them. No matter whether you count in minutes or seconds of nano seconds, midnight will fall between two of the things you are counting! (And hence will not even be assigned a number in your counting-off.)
Can someone remind me why we are talking about this? I forgot.
That is a false dilemma for reasons already adumbrated.
GR(rrrrrrr),
Is a point an interval?
Only if you want it to be.
Honest question though.
From a data perspective it is a null interval, an interval of 0. I may be looking at it from the very lopsided view of my experience though… Most folks are smarter than me so I’m willing to think about being wrong.