The reason some languages write down the accents while others don't

Question

This may be a difficult question to answer but I'm curious as to the reason for this.

The word película in Spanish is pe-LEE-cu-la. It has an accent to mark how to say the word.

The word peninsula in English is pronounced pen-IN-su-la. But it doesn't have an accent mark. It seems like we simply learn how to pronounce this word at one point in our lives, and then from then on out, the written word reminds us of the pronunciation. (I don't think the pronunciation is inherent in the way the word is spelled, similar to how worse and horse are pronounced differently, or tear has multiple pronunciations for different meanings).

It seems like accents are a bit repetitive. It seems that you could just put together a dictionary of pronunciations, and then learn the word pronunciation once from the dictionary, and then this makes the writing a little easier, since you can omit the accent.

Then the idea of a written word is simply a helper or tool to invoke a memory of the pronunciation. You already have to remember the definition of the word (it's not like the definition is written next to every word you read). Likewise, the accent marks can be omitted.

The only reason I can see accent marks being useful is when it is not your first language and you need that extra help all the time to remember how to say things. Or perhaps the accent marks like in Spanish serve to standardize how the population speaks. I'm not sure. Wonder what the history of accent marks was in Latin. They seem to have a lot, but maybe that evolved and there is some history to it. Anyway, that's probably a separate question.

Answer 1

Many languages have some sort of "stress", which might be realized in a number of different ways phonetically. English, Spanish, Classical Latin, and Ancient Greek all have/had this.

In some languages, like Classical Latin, the stress was completely predictable (even if the rules are a bit complicated). The same is true in Modern French: words are always stressed on the last syllable. Similarly in Old Norse, words were always stressed on the first syllable of the root (ignoring any prefixes); in Swahili, words are always stressed on the second syllable from the end.

In other languages, like Ancient Greek (for nouns in particular), the stress is utterly unpredictable. There's no way to know which syllable it should fall on. So Ancient Greek is nowadays (i.e. since Hellenistic times) written with diacritics, the acute, circumflex, and grave, to indicate where the stress falls. For example, ἄνθρωπος ánthrōpos "human" is stressed on the first syllable.

In yet other languages, like Spanish, the stress is usually predictable but sometimes irregular. So in Spanish, an acute accent is used to mark the stressed vowel only in the irregular cases.

English is most like Ancient Greek in that there's no solid rule for predicting stress. But unlike Ancient Greek, we don't mark the stressed vowels in any way. This is really just a historical accident; English has been very averse to changing its writing system even as the spoken language changes around it, which is how we've also ended up with silent letters and our mess of "five" vowels. Russian has similarly unpredictable stress and also doesn't generally mark it, except in dictionaries.

As a side note, Classical Latin used only one diacritical mark, the apex (which evolved into the acute accent, and is nowadays normally replaced with a macron). But there's a vast number of languages which use the Latin script, including English, Spanish, Swahili, and many others. Many of these have a need for some diacritics that others don't. So Unicode has ended up with quite the collection of them!