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Enumeration Cogitation: A New Decade?

January 4, 2010

Over the last few weeks I’ve noticed a lot of talk about January 1, 2010 marking the beginning of a new decade.  There have been many “decade’s best” lists, “decade in review” programs, and prognostications about the forthcoming “new decade.”  My initial reaction was to question my own understanding that the “new decade” does not start until January 1, 2011.   Moments later I was confident with my logic and figured that all of the current talk regarding the last/ new decade was yet another manifestation of bad math.

If you subscribe to the standard definition of a “decade,” then just measure off ten years from any point in time and you have one.  No issues.  Technically, Jan 1, 2010 does start a new decade;  as does Jan 1, 2011.  For that matter, I could arbitrarily declare that March 22 of any particular year starts a new decade.  In the classical sense of the term, however, I do not believe a new decade was begun on this past January 1.

At a gathering this past weekend I floated this query to a few of the attendees.  I was highly confident that my thinking was correct.  However, when given a whiteboard and a half-glass of whiskey to demonstrate my point, I failed.  I started with the period of Jan 1, 2000 to Dec 31, 2000 and numbered it as One;  Jan 1, 2001 to Dec 31, 2001 was corresponded to Two; and so on.  As I wrote out “12/31/2009” on the board I could see that this was the tenth annual period, marking the end of a decade.  In the interest of unity and humility I conceded that I was incorrect and focused my attention on the promise of late night Nerf gun warfare.

Having returned home, I was cogitating in the washroom last night while brushing my teeth.  Not feeling at ease about my failed mathematical proof on the whiteboard the night before, the subject subconsciously buoyed to my cerebrum.  I cogitated. And then I cogitated some more.

The first year ever was Year 1, not Year Zero.  The first decade of all time was Year 1 through Year 10.  It follows that the first decade of the 20th century was 1901 to 1910; and the first decade of the 21st century was will be 2001 to 2010. Think in terms of how we define centuries.  The 1st Century, or first hundred years, consisted of years 1 through 100.  Note that there is no Year 0.  As the end of Year 1 would mark the start of Year 2, the end of that 100th year marks the start of the next century.  January 1, 101 marked the start of the 2nd century.  Skipping ahead nearly two thousand years, let’s think of December 31, 1999.  That was the end of the 99th year in that century, which is important to recognize as the 20th century.  Following through, December 31, 2000 marked the end of the 100th year in the 20th century.  Many folks erroneously add one (1) to the two first preceding numbers in the year to determine what century it is.  While it is correct to say that 1736 and 1799 both lie in the 18th century, an occurrence on September 27, 1800 is not a 19th century event.  It simply occurred in the 100th year of the 18th century.

In summary, January 1, 2001 marked the start of the first decade in the 21st century.  One minute following 11:59 p.m. on December 31 of 2001, the first full year of the 21st century was complete.  Year 1 ended on 12/31/2001.  It follows that Year 2 ended on 12/31/2002 … And Year 9 ended on 12/31/2009.  The tenth, and final, year of the first decade of the 21st century will be complete on 12/31/2010.

If you think that December 31, 2009 marked the end of decade, tell me which decade got shorted out of a year.

Is my thinking correct or should I go cogitate some more?

  1. Probitee permalink
    January 5, 2010 6:35 pm

    The truth is that there are ordinal year names and those who subscribe to ordinal years see 2001-2010 as the current decade. However those who follow cardinal year names naturally choose 2010-2019 as the current decade. Other considerations should be noted in that the church had input about the calendar and how it is numbered.The most common calendar is the Gregorian calendar with a counting origin of 1, but there is also an astonomical calendar in which year counting starts at 0. You may recall the popular debate surrounding the lead up to the year 2000 celebrations and whether it was actually the start of a new millennia. The issue is tied to the convention of using ordinal numbers to count millennia as opposed to using cardinal numbers. The use of ordinal numbers is common in English speaking countries.

    • Hugo permalink*
      January 7, 2010 11:34 am

      Very informative, Probitee. Thank you. In summary, I am ordinary and reside in an English-speaking country and, ipso facto, the fruits of my cogitation were correct … at least partially.

  2. Kristi Nastars permalink
    January 5, 2010 7:51 pm

    You are correct..stop making your brain tired…. 🙂

  3. Tim permalink
    January 8, 2010 9:58 pm

    Keep on top of the big issues, pal. Glad you got my back in the world. Saw Hugo on TV the other day. Watching “Biography” on Pee Wee Herman (what?), there was Hugo, hanging out at the end of PW’s arm during a skit on an ’81 HBO special. Probitee nailed it, This issue has been on the ‘net lately. Straight Dope did an in-depth answer on this query. 71-80, correct. 70-79, more intuitive. Sidebar – Hugo, are you saying two-thousand ten or twenty-ten? How do you punctuate it? I’ve also heard “oh-ten” like “oh-nine”. Sounds wrong. Hugo, do you believe in time travel? Two funny time things:

    Sir, do you know time it is?
    me: yes
    (walk away)

    Excuse me, what time is it?
    me: time to get a watch. ( i say it every time. also gets a chuckle, and a shamed smirk.)

    Over and out, Timmy Time

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