Why Why Why Why isn't it IIII?

April 26, 2009 5:20 PM

Why is 4 IV and not IIII? Why is 9 IX and not VIIII?

From what I've been able to Google and Wiki, it sounds like that's the way they were written in ancient Roman times, but changed sometime in the 13th century. But why? What's the reasoning behind it?

A coworker asked me because I'm a fount of useless knowledge, but I don't know, and I haven't been able to find out, and now it's driving me nuts! Thanks!

posted by Caravantea to Writing & Language (17 answers total)

Actually, the Romans apparently did do it that way. Both IV and IIII are apparently used. IIII is still commonly used on clocks. Usage does not seem to have been consistent.
posted by valkyryn at 5:27 PM on April 26, 2009

IV is easier to read, shorter and more distinct from III.

But according to Straight Dope, no one really knows.
posted by Brandon Blatcher at 5:34 PM on April 26, 2009

Here is some speculation from the Straight Dope.

My favorite possibility is because using "IIII" instead of "IV" makes it such that you can cast four identical slugs of "XVIIIII" to create the letters used on a single clock face.
posted by Flunkie at 5:35 PM on April 26, 2009 [1 favorite]

http://en.wikipedia.org/wiki/Roman_numerals

Dunno if you missed it in Wikipedia, but there seems to be a fairly basic explanation. As the alphabet was Latinized, it began to adopt the subtractive notational form. To understand why I guess you would need to understand Latin better than I do though.
posted by mrmojoflying at 5:36 PM on April 26, 2009

Medieval people used IIII and VIIII all the time. One might argue that it was easier for them to conceptualize, though it's a slippery slope once you get going about how "unsophisticated" medieval scholars were, since they weren't nearly as bad as most people think. Still, the facts in this case do seem to speak for themselves to a certain extent.
posted by hiteleven at 5:41 PM on April 26, 2009

Response by poster: mrmojoflying.... yeah, Latin is not my language. I'm wondering why a subtractive notational form would have an advantage? And why IV for 4 and not IIV for 3? (I know there are examples of things like IIX occuring, but it doesn't seem to have ever been a standard system) This seems odd, especially since the shift seems to post-date (or come at about the same time as, depending on which wiki article you're looking at) the introduction of Hindu-Arabic numbers to Europe which were vastly easier to work with.

Also, some have noted that it does often appear IIII on clock faces, but I'm more curious about in things like names, outlines, chapter titles....
posted by Caravantea at 6:16 PM on April 26, 2009

I've always assumed it was for efficiency. (IV is easier to write than IIII, etc.) It was a lot harder to write anything then, so it would make sense to develop your notational systems so they waste as few motions as possible.
posted by nosila at 6:19 PM on April 26, 2009

I'm wondering why a subtractive notational form would have an advantage?

The two extra characters from IV to IIII are no big deal for us to type on a keyboard, but they were probably a big deal if you were trying to carve them into stone or even write in a fancy script.

Allowing subtractive notational form doesn't lose any expressiveness, but it lets you write some numbers using fewer characters. I'm guessing it was added as an optimization by some clever person who had to write lots of numbers, and then people used it inconsistently because they didn't know it or didn't care, or because they were keeping a tally on a write-once medium (II -> III -> IIII)
posted by qxntpqbbbqxl at 6:34 PM on April 26, 2009 [1 favorite]

Regarding the shift to Hindu-Arabic numbers, the transition was not as quick or as simple as if often thought.

Hindu-Arabic numbers first only became popular among the merchant class in Northern Italy, say around the late 13th century. The advantages for merchants of such an efficient number system are obvious.

However, merchants were not well-regarded among the traditional elites of medieval society - that is, churchmen and landed noblemen. Noblemen saw these upstarts (rightfully) as a threat to their own power, while churchmen found their focus on the material world, as opposed to the spiritual, distateful.

So since much of medieval society didn't like the merchants, they wouldn't have readily adopted their numbers - hence the continued use of Roman numerals for quite a long time after the introduction of Arabic numbers.
posted by hiteleven at 6:56 PM on April 26, 2009

I recall a tongue-in-cheek commentary around December of 1999 in which scholars debated how the turn of the first millennium was received. A point made was that chants and ledgers that used dates had always had space for a certain number of syllables or lines. Perhaps "IIII" took up more space in the manuscripts than "IV" and was therefore avoided?
posted by jefficator at 7:17 PM on April 26, 2009

IV is three strokes. IIII is four, so IV is easier.

III is three strokes. IIV is four, so III is easier.
posted by Chocolate Pickle at 9:35 PM on April 26, 2009 [2 favorites]

hiteleven: So since much of medieval society didn't like the merchants, they wouldn't have readily adopted their numbers - hence the continued use of Roman numerals for quite a long time after the introduction of Arabic numbers.

... until, notably, Vieta's sixteenth-century importation and refinement of the recently-developed Arabic extension into symbols of the Greek geometric arts, which he termed 'Algebra.' This fantastic book lays out in detail why Vieta's creation of 'Algebra' fundamentally changed the way we view numbers and mathematics, probably for the worse.

Caravantea: ... the introduction of Hindu-Arabic numbers to Europe which were vastly easier to work with.

This is a complete fallacy. It may seem as though our numbers are easier to 'work with,' but that's because they're what we're used to. In my own opinion, more worthwhile and in-depth mathematics was done before the last five hundred years, anyhow; and, while anyone is free to disagree with me, I wish people would confirm this before simply assuming that no one could do math until they discovered Arabic numerals.

And besides, what no one ever mentions when they talk about the 'handicap' of Roman numerals is that any well-educated Latin, especially near the end of the empire, would not have done math with Roman numerals anyhow; they could and should have used Greek numerals, which are purely base-ten just like Arabic numerals (and in some ways more precise, since it distinguishes between tens, hundreds and thousands by character as well as place) and which they would have been familiar with from the Greek mathematical texts they studied when they were in school.
posted by koeselitz at 4:27 AM on April 27, 2009

I should say this: the fallacy that Arabic numerals are 'easier to work with' than Roman numerals stems from the deeper fallacy, endemic to modern thought, that symbols are equivalent to the things themselves.
posted by koeselitz at 4:34 AM on April 27, 2009

I'd also suggest that, at a glance, IV is easier to read (for me at least) than IIII. The latter makes me do a double-take and verify the number. I think the idea that IV is faster to write/carve is also a good one.
posted by empyrean at 4:47 AM on April 27, 2009

keoselitz- how would it be easier to work with a notational system where the name of the number changes relative to where it is? Isn't that an added layer of complexity? If I'm adding 42 and 98 using arabic numerals, I just work the columns and I'm done. Using the greek numerals, it appears that I'd have to do conversions. It almost seems like their numbering system isn't base 10, but base 1000. Every number from 0-999 has a different name, just as base 16 has a different name for each number from 0-15.

I should say this: the fallacy that Arabic numerals are 'easier to work with' than Roman numerals stems from the deeper fallacy, endemic to modern thought, that symbols are equivalent to the things themselves.

I don't follow.
posted by gjc at 4:57 AM on April 27, 2009

Mark Chu-Carroll's theory: shepherds cut notches on their staffs to count their sheep.
posted by Carol Anne at 5:28 AM on April 27, 2009

I think this debate over the "usefulness" of Arabic numbers is wildly off-topic (I through in my two cents because I felt it informed the discussion in terms of dating the use of Roman numbers).

But while we're on the subject, it should be noted that there is a big difference between mathematics as a scientific/philosophical pursuit, and mathematics as a day-to-day tool. Any genius can use any numbering system to devise mathematical theory, but double-entry bookkeeping for business use was only popularized with the introduction of arabic numerals. Arabic numerals meant that more people could do basic math for quick, practical calculations.

The OP was also interested in the use of numbers in general, not in mathematics. And Roman numerals were used - and still are used - for many purposes that have nothing to do with math (chapter headings being a good example).
posted by hiteleven at 6:01 AM on April 27, 2009