Is it now the 2nd decade of 21st Century, or still the first decade

This seems to be an area of debate, whether or not 2010 is the beginning of the 2nd decade of the 21st century or the end of the first decade.

I am curious to hear opinions, backed with evidence/facts, regarding this matter.

Technically any period of 10 years is a decade, however people tend to think in terms of 70’s, 80’s ,90’s etc. Based on that logic it would seem to suggest that 2010 is the next decade, however as the common calendar years starts at 1, which implies that a year ending in one is the start of a decade.

The straightforward answer is that it depends what you mean by “decade” and there’s no precise answer.

People who insist that the years 2000 through 2009 inclusive are not a “decade” are wannabe-pedantic nitwits. It quite certainly is, and it’s the commonly understood meaning of the term. 2001-2010 is also a decade, but it would be rare that you would need to describe it as such.

AD 1-10: 1st decade of the 1st century
AD 11-20: 2nd decade of the 1st century
AD 21-30: 3rd decade of the 1st century
AD 1901-1910: 1st decade of the 20th century
AD 1991-2000: 10th decade of the 20th century
AD 2001-2010: 1st decade of the 21st century

I think it is the second decade now.

We usually think about sets of ten years in the same manner already. 1920-1929 = a decade, why not 1910-1919 and 1900-1909?

Thanks for poisoning the well. Anyone who disagrees with you is pedantic nitwit. But the whole point of a question like this is to want a pedantic answer.

The statement in question is “decade of the 21st century”. It’s already been argued ad nauseum that 2001 was the start of the 21st century. Ergo, since the year 2000 is not part of the 21st century, it cannot be part of any “decade of the 21st century.”

It has nothing to do with saying whether 2000 - 2009 was a decade, or wheter 2001 - 2010. They’re both periods of 10 years, so they are both decades. And there’s nothing wrong with referring to either one. But if you are insisting on exact language, the answer to the OP’s question is “last year of the first decade.” If not being pedantic, the question is unanswerable: insisting either way requires pedantry.

But different periods of 10 years are referred to in different ways. If the OP had asked whether we were still in the Aughts (or whatever you want to call the years with a 0 in the tens place), then the answer is clearly no. However, when phrased the way the OP did, the answer is yes, we’re still in the first decade of the 21st century.

For a century comparison, the 20th century and the 1900s have near-total overlap, but the year 1900 was part of the 1900s but not part of the 20th century, and the year 2000 was part of the 20th century but not part of the 1900s.

That’s not precisely what I said, if you want to be pedantic.

Define “century.”

Both the previous posts assume “the 21st century” must necessarily begin in the year 2001. In fact, however, that is not what the term “the 21st century” is commonly understood to mean. So it is perfectly correct to say that this is the first year of the second decade of the 21st century, going by what most English-speaking people are referring to when they say “the 21st century” - the years 2000 to 2099, inclusive.

Defining “century” in popular usage as being a period of a hundred years that begins with the same two digits is every bit as logical as defining “decades” by what the third digit is. And in fact that’s how people usually do it. Defining it was being the years 2001-2100 inclusive is technically true as well, for a different meaning of “21st century.”

Both answers are still correct.

So it’s perfectly correct, then, so say that the 1st century only had 99 years.

Which means you haven’t answered the question. “Both” was not one of the options given. To pick a side, you have to be pedantic. And the pedantic people are the ones that are going to stick with rigid definitions.

As for what most people mean: I submit that most people don’t have an opinion one way or the other. And that most people that do have an opinion choose the answer I’ve already given.

Au contraire. That is exactly what the term is defined to mean and commonly understood to mean (a poll of you and your friends does not pass muster for “commonly understood”). Perhaps you’re mistaking the 21st century with the 2000’s.

It’s better to say, “definitionally” rather than “technically.” At issue are definitions and not science.

The most widely accepted civil calendar, the Gregorian calendar, is itself essentially a result of voting in an effort to create calendar years which reflect orbital years but maintain the vernal equinox in a seasonal position.
In short, all calendar-based terms like “year,” “decade” and “century” are not astronomical definitions but arbitrary terms.

Have fun parsing out which side of the argument you want to champion, but if you want to join the very pedantic ranks, you can out-pedant the amateur pedants by pointing out that midnite on December 31, 2001 did not mark exactly 2000 orbital cycles since 00:00 Jan 1, 0001. Therefore those who missed the millennial celebration at the start of 2000 did so having also hooked up their cart of pedantry to the donkey of ignorance.

In daily life, the best choice is to mark the beginning of ordinary decades as the beginning of that decade, and stop worrying how many prior full decades would get you back to the start of year 1.

Unless you want to say

BC1 - AD9 the first decade of the 1st century
AD10 - AD 20 the 2nd decdade of the first century.

BC1 - AD99 the first century

It’s all how you define it

Sure. I hereby define this year to be the start of the 10,000th century.
And a century is type of flat bread.

It’s all how you define it. :dubious:

Considering the complete shamozzle that entailed in the development of the Julian Calendar, I think it safe to say that when the year 1 was decreed, it was a mistake that they did not decide to actually begin with the year 0, and we should have retroactively slipped it in when we changed to the Gregorian Calendar. Consider that the Astronomical Calendar does exactly that.