The "end of the decade" argument

Once upon a time, I was a purveyor of this type of idiocy, so I suppose I should be more amused than irritated, but this comment, from Marc Thiessen and others (including, as noted, past-Lyford), is, well, idiocy. And it gets very tiresome.

2010 is the last year of the decade. The new decade begins in 2011!

It's the "I'm smarter than you are" comment. And it's idiotic.

• A decade is a period of ten years.
• Period. End of definition.
• By definition, a decade ends in any instant which is exactly 10 years later than some other identifiable instant.
• A decade ends this morning at 9:59. A decade ends this morning at 10:00. A decade ends this morning at 10:01. Etc. Etc.
• We group decades and give them names as a short-hand for referring to a time period.
• Some people try to make this more complicated than it is.
• These people overload the term "decade" to include the proposition that decade x has the property of being the "x/10"th decade since the birth of Christ, or the beginning of the Common Era, however one wants to define the current year numbering scheme.
• There was no year 0.
• Therefore, the decade ending in the year 9 included the year 1 BC (or BCE)¹.
• The decade beginning with the year 1 ended in the year 10.
• This was the first decade of the Common Era.
• Some people use this to argue that decades cannot end in years ending in 9, but only in years ending in 0.
• This position is pedantic, semantic, sophist and obnoxious.
• The decade of the "20-aughts" includes all of the years numbered 200x.
• The "20-10s" will include all of the years numbered 201x.
• The 1990s included all of the years numbered 199x.
• Etc. Ad infinitum.

And I will have a couple of "end of decade" posts over the next couple of days...


¹ - All of this ignores, of course, that Jesus was actually born in 4 BC or 6 BC.