- The eighteenth century, if it is to have a coherent character, must be allowed to divest itself of strict chronological limits and wriggle itself into the period from 1660 to somewhere in the 1780s; that is, from the Restoration to the decade when the American Revolution triumphed, the French Revolution began, and the Industrial Revolution got underway with Cartwright's power loom and Watt's steam engine.
The term "nineteenth century" is another verbal convenience of some elasticity. If you want it to mean a century, you use it to cover the period 1815-1914. The quarter-century from Bastille to Waterloo, 1789-1815, is then fitted in as a sort of entr'acte between eighteenth and nineteenth, featuring a special performance by the French Revolution and Napoleon.
-- Barbara Tuchman, Bible and Sword
lilairen's rant reminded me to post one of mine from about ten years ago that's come up again recently: What's with people pedantically claiming that this New Years wasn't the end of the decade, because technically decades start with years ending in 1?
Technically, any ten year period is a "decade". 1988 through 1997 was a decade. 1999 through 2008 was a decade. It actually doesn't need to even be a group of whole numbered years - decades start, and end, every day. The question isn't whether it was the end of a decade, because it obviously was; the question is which decade are we talking about when we say "the decade."
When it comes to centuries, the pedants have a point, because the way we name our centuries implies that we're counting them one by one from the beginning. While the years 1900 through 1999 were most certainly a century, "the twentieth century" is not quite the right name for that period.
But decades? We don't see people calling them names like "the two hundred and first decade". You'd have to be daft to claim that the decades we referred to as "the twenties" or "the 1980s" must necessarily have begun in 1921 and 1981 rather than 1920 and 1980. Not only is it obvious what decade people mean when they say this December 31st was the end of "the decade", but the way we name decades is just as clear.
So, just to be clear:
- The 20th Century AD: 1901 - 2000 (which is a century)
- The 1900s: 1900 - 1999 (which is also a century)
- The 202nd Decade AD: 2011 - 2020 (which is a decade)
- The 2010s: 2010 - 2019 (which is also a decade)
- Any roughly 100-year period you name and describe in context: also a century.
- Any roughly 10-year period you name and describe in context: also a decade.
Next time someone says "the decade" didn't just end, ask them how often they've heard anyone talking about "the two hundred and first decade".