When Does The New Century Start?

When Does The New Century Start?

Most people assume that the 21st century starts with 2000, but a vocal minority insists that it starts with 2001. This article presents some background on the issue, and explains who is right and why.

The numbering of years in the Gregorian calendar notionally starts from the birth of Christ. I say “notionally”, because it cannot in fact be so; King Herod, who is supposed to have ordered the Slaughter of the Innocents after hearing of the birth, died in 4 BC.

Anyway, the notional birth of Christ was supposed to have taken place in the year 1. This numbering was not actually proposed until sometime in the sixth century, in the year that eventually became known as 525 AD. Thus, there was never in fact any year 1—the numbering before 525 was entirely retrospective.

The reason why the numbering was proposed to start from 1 instead of 0 was because the mediæval Europeans had not yet received the concept of zero from the Indians. These days, of course, the concept of zero is widespread. So widespread, that the idea of numbering the years from 1 is getting to seem less and less natural.

For example, no less an author than Jared Diamond, in his Guns, Germs and Steel, shows, in figure 17.2 (on page 341 in my edition), the Austronesian expansion reaching the Marquesas in “AD 0”. Did he stuff up? Or did he simply realize that putting “AD 1” would suggest knowing the date that people reached those islands to the exact year, whereas putting “0” does not necessarily imply the same accuracy? Could this be the same reason why archaeologist Joyce Tyldesley, in her book Hatchepsut: The Female Pharaoh, puts a diagram of historical events at the end of the last chapter (page 235 of my edition), with a time scale that goes from 3000 BC up to—you guessed it—AD 0?

Following naturally on from this is the way of grouping the years into decades, centuries and millennia. Whichever year marks the start of the calendar is also the start of the first decade, the first century and the first millennium. However, the numbering is one thing, the actual start of the calendar is another. The Gregorian calendar in fact started from 15th October 1582. (And in some countries, it didn’t get adopted until much later—for example, 1762 in Britain, and 1911 in Russia.) I don’t know the full text of Pope Gregory’s proclamation, but did he in fact say that the first decade, the first century and the first millennium would all start with the year 1? Probably not—these were all simply assumptions that other people made later. They are not part of the official specification of the Gregorian calendar.

In short, those who say that, technically, the 21st century of the Gregorian calendar starts with 2001, are wrong: technically, we haven’t even reached the end of the first Gregorian millennium yet—we’re still in the early part of the fifth Gregorian century.

To sum up: the convention of numbering the years is just that—purely a convention. And a convention only works as long as sufficient numbers of people are prepared to go along with it. Most people would rather number the years from 0 than from 1, with appropriate corresponding numberings for the decades, centuries and millennia. If you disagree with this, maybe it’s time to stop fighting and switch.

OK, so this will mean changing all the BC dates by 1. So what’s the big deal? BC dates are, by definition, imposed retrospectively, so they have no correspondence to any written records of the time anyway. To avoid confusion, why not just drop the “BC” suffix for the renumbered dates, and use negative numbers with the “AD” suffix? Thus, the year of Julius Caesar’s death, 44 BC, becomes -43 AD. (1 BC, of course, becomes 0 AD.) Once it is understood that every year number, whether positive, negative or 0, is an AD year number, you can drop the “AD” suffix, as is commonly done with more recent dates. Thus, Augustus, first Emperor of Rome, ruled from -26 to 14.

It is quite rare for commonsense conventions to actually gain popular acceptance—witness the history of attempts to regularize English spelling. When it does happen, it seems to me it is something to be welcomed, not discouraged. Numbering the years from 0 makes far more sense than numbering them from 1, and people are actually keen on this, so let’s just do it!

Created 2000 April 27 by Lawrence D’Oliveiro, <ldo@geek-central.gen.nz>, last modified 2001 January 12.

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