Are we starting a new decade?

Here’s the basic logic:

The 20th century started in 1901 and ended in 2000.

The 1900’s started in 1900 and ended in 1999.

The 80’s started in 1980 and ended in 1989

We count decades by the starting digits, not by enumerating them. Therefore, we’re the second year of the 10’s.

Technically no, technically yes. You’re right that the second the clock turned to January 1, 2010, we were technically in a new decade (as the ten years of the previous decade had ended).

But most people still count that entire 0 year, as part of the decade.

The 1920s stretched from 1920 through 1929.

It is not referring to “the 1920th thru 1929th years of Our Lord”. It is simply the years starting with “192”. And everyone understands that. To insist otherwise is a silly a waste of time.

If someone wants to be pedantic and boorish like that, they must also take into account what year the Gregorian calendar was adopted.

That would be 1752 for Great Britain and its colonies and 11 days were skipped. So probably the pedants need to say the decade starts 11 days before (or is it after?) Jan 1, 2011.

Spain adopted the new calendar in 1582, Latvia in 1915, Germany in 1700 – the calculation is different for all different places – so those who want to be really precise should spend their time with this chart (and leave the rest of us alone).

@grumpyfish: Do not your first logical statement and your second contradict each other?

20th century started in 1900 and ended in 1999. Yes?

@grumpyfish‘s statements are consistent

The twentieth century AD started in 1901 if you are referring to “the twentieth 100-year span AD”. There was no year 0, so the first span was 1–100, then 101–200, etc.

However in universally understood parlance, the 1900s were 1900 thru 1999.

Any 4-digit year ending in a “1” is a new decade: 1991, 2001, 2011, 2021…

I agree with @grumpyfish and @jaytkay. The problem is that we have different ways of discussing time periods. Sometimes we talk about them in relational terms (e.g., “the fifth century”), and other times we talk about them in absolute terms (e.g., “the nineties”). The fifth century is constituted by the years 401–500, whereas the nineties comprise the years 1990–1999.

So when we ask if we’re starting a new decade, we need to know whether or not the question is posed in relational or absolute terms. The year 2011 starts the 202nd decade, but is the second year of this millennium’s teens.

Typically speaking, we think of centuries in relational terms and decades in absolute terms, which perhaps explains why we’re so often confused about these things.

I like to think we are starting a new decade, because the last 10 years didn’t do much for me. Technically I would say the decade runs year 0–9, but since we commonly count 1–10 maybe we can have it both ways?

@SavoirFaire How is 10 or 11 teens? I would guess teens is derived from the word ten, although I never thought about it, but teens in English generally is thought to begin with 13.

@JLeslie You are correct that the term “teens” is derived from “ten,” and it is true that we refer to young adults as teens only between the ages of 13 and 19. But “teens” is also the colloquial name for the years ranging from 10–19 within a century. That’s what the years 1910–1919 were called by my grandparents, for instance.

00–09 = Aughts
10–19 = Teens
20–29 = Twenties
(And so on.)

@SavoirFaire Makes sense.

The first year in the current calendar was not Zero, it was 1. So the first decade was
1—10 and the second decade started with 11. The fact we have piled 200 years on that doesn’t change the real start date. Yes, this January started the second decade of the Y2K, and the new millennium didn’t actually start till 2001, despite what poorly written computer software may have “thought” about it. :-).

@ETpro Now that is a good point. We went from year 1 BCE (BC) to year 1 CE (AD).

@JLeslie Yep. Zero was just the crossing point. My appologies for the typo in my comment. The number 200 should have read 2000.

Here’s a pertinent note from Wikipedia’s List of common misconceptions:

A belief that decades/centuries/millennia begin not on the year ending in 0, but rather on the subsequent year ending in 1 (e.g., “The current millennium didn’t really begin on January 1, 2000, but rather on January 1, 2001”)—based on an assumption that there was no year 0—are founded in an incomplete understanding of historical calculation. The currently dominant system of numbering years, known as the “Anno Domini” or “Common Era” system, was proposed by Dionysius Exiguus in 525 for application to the Julian Calendar (and later was applied to the Gregorian Calendar).[28]

For this reason, all year numbers prior to 525 are the result of calculation rather than historical record. Two systems of calculation exist in parallel: The Historical System, which holds that 1 AD/CE was preceded by 1 BC/BCE, and the Astronomical System, which incorporates a year 0, and thus has 1 AD/CE preceded by 0.[29] With scholarly works in which precision is important in BC/BCE years, it is necessary for the researcher to identify which system of calculation is being used. The Astronomical System (with a year 0) is reflected in ISO 8601, the standard published by the International Organization for Standardization that covers representation of dates and times.[30]

…but I’m not sure that I want to change my answer above.

@gasman While the Wikipedia article is certainly pertinent to the discussion, all it says in the end is that there are other calendars in which a year 0 is placed before year 1. But there are, of course, many alternative calendars. Buddhist calendars also include a year 0, and I doubt they are alone. Still, the tradition of labeling centuries ordinally (e.g., as the “second century” or “nineteenth century”) arose out of a tradition without a year 0 (i.e., the Historical System). Same with ordinally designated decades. Thus I do not think we need to change our previous answers, though it is interesting information all the same.

@SavoirFaire Well, I think there’s general agreement that the present decade is the 2000 -teens & the following decade will be the 2000 -twenties, and so on. I suppose a real pedant might claim that the period Jan 1, 1900 through Dec 31, 1900 was the beginning of the nineteen hundreds but not yet the start of the twentieth century. It’s an ancient conundrum : do we reference time by counting or measuring?

It also makes sense that (ordinal) century numbers begin with “first.” (Computer programmers, however, may want to call it the zeroeth.) This makes the 1900s the 20thC and the present century 21C. So far so good.

But we expect the beginning of a new decade, century, or millennium to coincide with the 10 – , 100 – , or 1000-year anniversary of the start of the previous period. Thus whether the initial year is labeled 0 or 1 in the system matters very much, because it will propagate forever into the future. In a zero-based system the second decade begins in year 10 (not 11), the second century begins in 100 (not 101) and so on. (If not, why not?)

Buddhist and other alternative calendars are of great cultural interest, but they don’t represent international standards. I hadn’t previously heard of ISO 8601, but if it represents some kind of new consensus among intelligentsia then maybe present new decade did start with 2010.

The late evolutionary biologist Stephen Jay Gould discussed the historical calendar debate in Questioning the Millennium, published in 1997. My copy is buried somewhere…

@gasman I don’t disagree with anything you said, and said much of it myself above. I certainly didn’t mean to say that whether or not there was a year 0 is unimportant. It obviously is. And my point about Buddhist calendars was just that of course there are alternative calendars, but the question seems to be asked in reference to one without a year 0.

ISO 8601 was new to me, too, though. And it’s a good point that you make regarding the possibility of a new consensus. I guess we will have to change our answers if everyone starts thinking in terms of the Astronomical System!