Why do we say 18th century?

Here is one possibility.

In England arabic numerals did not really take off until the mid-16th century, and roman numerals lack a real place-value system. Also note that roman numerals were still used to denote the Anno Domini years. Until we started to dump roman numerals for tracking years “seventeen hundreds” would not had made any sense.

Do we? I don’t recall if I ever heard that, or certainly not very often. You have to think twice to get what it means. Someone in his fourth decade is 30 to 39, right? (I even had to think twice more to convince myself that one’s fourth decade is ages 30 through 39 and not 31 through 40. Nobody wants to have to think that much!)

This would be the main reason for me. “The 1700s” could refer to either the entire century or the first decade of the century and for this reason, particularly in academic writing, I would avoid it. Certainly not mix them in the same sentence.

I usually use the 1700s because it’s clearer. If you use 18th century amongst a certain crowd, they get confused with which of the hundreds it is - do you go one up or one down? Or is it the same number? I make the same mistake if I’m not paying close attention, and (for some reason) it’s the earlier numbers; if anyone says the 11th Century I have to stop and really concentrate on which that is.

If we really dug into the history of the phraseology we’d probably find two competing “standards” imported from two competing languages. Or else one existing Olde/Middle English “standard” and one later import. So English just keeps using both “standards” despite the fact they’re redundant and mutually incompatible. English is like that.

It’s beyond my expertise to dig out the actual history, but even if we knew it that wouldn’t change the reality of today’s usage.

Aside, I’d quibble with the OP a bit. I find uses of “18th Century” and “1700s” to be about equally split. I suspect it depends a lot on what kinds of material one reads. Most periodicals probably have a definite preference for one over the other.

1700s: 1700-1799.
18th century: 1701-1800.

So be careful: Napoleon crossed the Alps in the 18th century, but not in the 1700s.

Just ran across this article , she’s entering her 10th decade.

http://www.independent.co.uk/news/people/profiles/honor-blackman-turns-90-hollywoods-toughwomen-owe-a-debt-to-the-avengers-star-10462108.html

Huh. I see it or the equivalent all the time. It’s extremely common.

Google search for fourth decade yields 7,450,000 hits.

The second hit is from the Dope: It’s official: I’m in my fourth Decade. (And yes, she gets the number wrong since she just turned 40. :smack:)

Because *Settecento *just sounds way better.

Another reason the pedants who insist 1900 is in the 19th century are wrong is that it makes the meanings of “19th century” and “1800s” slightly different.

Thus King Charles I of Spain was born in the (pedantic) 15th century but spent his entire life in the 1500’s. Exactly one century later King Charles I of England did a similar trick.

You’re not the Caliph of me!

Finnish uses “1700-luku” which is a lot closer to “1700s” than “18th century”. It’s taken me forever to try to learn the “18th century” thing and even after over 20 years of using English daily it still feels wrong.

We’re NOT wrong, because there isn’t anything wrong with them being different.

I’m pretty sure he did it in both notations, since the First Italian Campaign took place in 1796.

I totally grasp the concept, but I still have to mentally translate: mention the 18th century, and I’ll have to think “Oh that’s the… 19… no wait—the 1700’s. Why couldn’t they just say the 1700’s in the first place, instead of making me figure it out?”

So I appreciate this thread’s question.

I think we have a winner here.

Does anybody really know what time it is ?

It’s like how we call the 2000s the “Naughties”.

(Or am I the only one?)

Does anybody really care?

Yup. In discussing recent history, “the 1900’s” means a specific decade, not to be confused with “the 1920’s” or “the 1960’s.”

Some people might say the American Revolution happened in “the 1700’s.” They would be wrong. If people find “18th century” confusing–that just means that some people are easily confused.