New Year, New Decade: The Debate over When It begins
Are we a year ahead of ourselves or not?

With January 1, 2020, approaching and most of 2019 in the past, the debate about when the old decade ends and the new one begins is heating up. Some say it ends on December 31, 2019, and others claim it doesn’t end until December 31, 2020.
We like those even numbers, so one ending in zero fits the bill.
I found good arguments for both. One is historical and the other logical.
Historically, the argument is on the side of those who claim the new decade is still a year off.
Logically, you could argue that the decade 2020.
You decide.
Historical Argument
The A.D. (Anno Domini) calendar was devised by Dionysius Exiguus, a 6th-century monk who wanted to pinpoint the day for Easter. To do that, he had to identify the year of Jesus’ birth, so he devised a system based on the year he believed Jesus was born.
Dionysius used Roman numerals, and there is no Roman numeral for the number zero. Therefore, the Christian calendar identified the date of Jesus’ birth as Year 1, not Year 0. So yes, there’s a gap. This means that 1 A.D. began immediately after the end of year 1 B.C., and one full year was not accounted for.
However, he never included the years before Jesus’ birth in his calculations.
Fast forward to 731 A.D. to Anglo-Saxon England when the Benedictine Monk Bebe the Venerable, or Saint Bebe, popularized the Anno Domini era and included the years before Jesus’ birth.
Sadly, he again did not include a year zero, so the era went from 1 B.C. to 1 A.D., so in 1999 we were still one year short of two full millennia. Therefore, in 2020 we are still one year short.
Logical Argument
Historically, we can agree that the number zero was not recognized way back when man/woman started keeping track of time.
Logically, however, time started at zero no matter what name you give it, and it was the first year, Year 1. So what they called Year 1 was the beginning of Year 2. Therefore, in year nine, there were ten years or 0–9 completed.
That means the year ending in zero is the beginning of a new decade.
Second, a decade is ten years. Therefore, the decade and the second coming of the twenties begins with the number that has two in the tens column, i.e., 2020.
However, if you’re talking about a new millennium, it’s 2021.
Call it what you want. As Linda Richman (SNL — Coffee Talk) would say, “discuss amongst yourselves.”
It’s confusing, and in the larger scheme of life, it doesn’t really matter.
What I think is even more interesting is that a Christian monk decided that time would begin all over again beginning with the birth of Jesus Christ and everyone went along with it.
But I digress.
One thing is for sure. If you make it to January 1, 2020, it means you’re still alive.
And that’s a great reason to celebrate.