What are multiple writing systems used for in a single language?

Question

I've created a phonemic alphabet. I realize that because it is phonemic, I do not need spaces or other markers to separate words; the spelling doesn't matter because each letter has one sound and doesn't change, even based on the letter around it. Thus I have two ways to write the same thing, and I was thinking I would use them differently.

I don't know a lot about linguistics. Based on the way other languages work, like Japanese, what are multiple systems used for in a language? For example, formal vs informal speech?

edit:

Phones I am aware of 33 different phones in the English language. Of these I use 30 because some of the sounds are redundant/uncommon (v and w are very similar so I use w, and the "xh" phone in "the" can be replaced with the "th" phone in "theory", and the "zh" phone in "casual" is rarely used).

With these 33 or 30 phones I have created an alphabet.

No Markers In English letters make different sounds based on the surrounding letters, like the word "change", where "c" followed by "h" makes the "ch" sound, the "g" makes the "j" sound, and the "e" is silent. Because my alphabet is phonemic (the letters don't change phones), I am able to string words together without markers that separate them; spelling no longer matters, just the sounds.

Answer 1

A recent post on LanguageLog discusses this very question in the particular case of Korean. For centuries, Korean has been written in a mixture of Chinese characters and Hangul. In most contexts today, only Hangul is used; but here is a case where it has been written entirely in Chinese characters, apparently because of the formality of the occasion.

Answer 2

Your alphabet is completely phonetic? Are you sure? The Sound Pattern of English feature system has around 17 orthogonal features which, even if they are all binary valued, gives 2^17 distinct sound segments. That takes a pretty big alphabet. (Though not all sounds occur in all languages.)

I don't know why you think that a phonetic alphabet doesn't need word spaces. Some writing systems have not marked word divisions, but I don't think it has to do with how phonetic the system is.

Trying to answer your question, my impression is that different writing systems for a single language have been maintained by different religious groups of a community.

Answer 3

There is already such an alphabet: the International Phonetic Alphabet. I assume that you mean that you've created an alternative to the IPA (perhaps one omitting nonexistent sounds, depending on what language this is supposed to be for).

Competing alphabets (and abjads / abugidas -- a technical distinction in kinds of non-pictographic writing systems) reflect social distinctions of some kind. The indigenous Vai syllabary is used I suppose you would say to be "traditional", but Latin-based letters are used to be "modern". The most frequent divide, as far as I know, is religion (e.g. Sindhi which is written in Devanagari, Gurmukhi and Arabic which roughly aligns with the Hindu / Sikh / Muslim division). There are also nationality-based distinctions such as Latin alphabet for Kurdish in Turkey vs. Arabic script in Iran and Iraq, or traditional Mongolian script in Inner Mongolia (China) vs. Cyrillic in Mongolia (or, Latin on the interwebs). Likewise, Canadian Aboriginal syllabics are used along with Latin script, depending on language and dialect, province (Nunavut vs. Labrador Inuktitut).