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A millennium is a period of time equal to one thousand years. There are two main viewpoints about naming millennia and there was a popular debate leading up to the celebrations of the year 2000 as to whether 2000 was the beginning of a new millennium. Historically, there has been debate around the turn of the millennium, centuries and decades before.

Counting years


The original method of counting years was ordinal, whether 1st year AD or regnal 10th year of King Henry VIII. This ordinal numbering is still present in the names of the millennia and centuries, for example 1st Millennium or the 20th century, and sometimes in the names of decades, e.g. 1st decade of the 21st century.


In recent years, most people have moved to counting individual years as cardinal numbers, for example 1945 or 1998. The usage 1999th year AD is no longer found. This follows scientific usage, for example astronomical year numbering. As a result, some other calendar names have also moved to cardinals, e.g. 1980s is an acceptable name for a particular decade. However, 1600s could be understood as either a decade or a century.


Although the above change from ordinals to cardinals is incomplete or may never be completed, the main issues arise from the content of the various year ranges. Similar issues affect the contents of decades and centuries.

Those following ordinal year names naturally choose

  • 2001-2010 as the current decade
  • 2001-2100 as the current century
  • 2001-3000 as the current millennium

Those following cardinal year names equally naturally choose

  • 2000-2009 as the current decade
  • 2000-2099 as the current century
  • 2000-2999 as the current millennium


As a side-note to the debate on timing of the turn of the millennium, the arbitrariness of the exact date bears highlighting. Firstly, the Gregorian calendar is the (secular) de facto standard, but is based on a significant Christian event, the birth of Jesus; thus the foundation of the calendar has no meaning to any non-Christian celebrants. Additionally, the calendar is one amongst many still in use and those used historically. Secondly, adjustments and errors in the calendar (such as Dionysius Exiguus's incorrect calculation of AD 1) make the particular dates we use today arbitrary.

However, given that Gregorian calendar is an accepted standard, it is valid to discuss the significant dates within it, be it the timing of religious festivals (such as the moving date of Easter which Dionysius Exiguus was involved in calculating) or the delineation of significant periods of time, such as the end of a millennium.

Finally, although post-2000 the significance of the debate is greatly diminished, we have only to wait until the turn of the next decade, century or millennium for it to rear its head again!

Viewpoint 1: xx01-xx00

Those holding that the new millennium should be celebrated in the transition from 2000 to 2001 (i.e. December 31 2000), argued that since the Gregorian calendar has no year zero, the millenniums should be counted from AD 1. Thus the first period of one thousand complete years would be from the beginning of AD 1 to the end of AD 1000, and the beginning of the second millennium would be celebrated in the transition from 1000 to 1001. The second millennium would then end at the end of the year 2000.

Illustration of years with a 00-01 demarcation
2 BC 1 BC AD 1 AD 2 3 4 5 ... 998 999 1000 1001 1002 ... 1998 1999 2000 2001 2002 ... 2998 2999 3000 3001 3002
First one thousand years (millennium) Second millennium Third millennium

Arthur C Clarke gave this analogy (from a statement received by Reuters): "If the scale on your grocer's weighing machine began at 1 instead of 0, would you be happy when he claimed he'd sold you 10kg of tea?"

Viewpoint 2: xx00-xx99

The "year 2000" has also been a popular phrase referring to an often utopian future, or a year when stories in such a future were set, adding to its cultural significance. There was also media and public interest in the Y2K bug. Thus, the populist argument was that the new millennium should begin when the zeroes of 2000 "rolled over", i.e. December 31 1999 - see astronomical year numbering. This is similar to the common demarcation of decades by their most significant digits, e.g. naming the period 1980 to 1989 as the 1980s or "the eighties". Similarly, it would be valid to celebrate the year 2000 as a cultural event in its own right, and name the period 2000 to 2999 as "the 2000s".

Illustration of years with a 99-00 demarcation
-1 0 1 2 3 4 5 ... 998 999 1000 1001 1002 ... 1998 1999 2000 2001 2002 ... 2998 2999 3000 3001 3002
First one thousand years (millennium) Second millennium Third millennium

The majority of "millennium" celebrations were held at midnight on December 31 1999 / January 1 2000 reflecting the popular mood.


Stephen Jay Gould noted in his essay Dousing Diminutive Dennis' Debate (or DDDD = 2000) (Dinosaur in a Haystack ) that celebrations and media announcements marked the turn into the 20th century along the 1900-1901 border (citing, amongst other examples, the New York Times headline "Twentieth Century's Triumphant Entry"). He also included comments on adjustments to the calendar, such as those by Dionysius Exiguus (the eponymous Diminutive Dennis), the timing of celebrations over different transitional periods, and the "high" versus "pop" culture interpretation of the transition. Further of his essays on this topic are collected Questioning the Millennium : A Rationalist's Guide to a Precisely Arbitrary Countdown.

In the editorial to 2002's Best American Essays Gould highlights the use of historical events, rather than transitional dates, to delineate periods of history: "Many commentators have stated quite correctly in my view that the twentieth century did not truly begin in 1900 or 1901, by any standard of historical continuity, but rather at the end of World War I, the great shatterer of illusions about progress and human betterment... I suspect that future chroniclers will date the inception of the third millennium from September 11, 2001."

(Similarly, some commentators delineate the Middle Ages from the Fall of the Western Roman Empire to the Fall of Constantinople.)

Douglas Adams highlighted the sentiment that those in favour of a 2001 celebration were pedantic spoilsports in his short web-article Significant Events of the Millennium. This sentiment was also demonstrated when, in 1997, Australian Prime Minister John Howard made a point in favour of the 2001 celebration and was named "the party pooper of the century" by local newspapers.

See also

External links

  • The full text of DDDD = 2000 on the Dilettante Press website:
  • Significant Events of the Millennium

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