There’s an article in the Japan Times about how ‘katakana Japanese’ – in this case, non-Chinese loans, mostly from English – is ruining the Japanese language. Not all that surprisingly, the author claims it’s the writing system that’s to blame. Surely, they argue, if these new loans were written in kanji, there’d be no confusion because all Japanese people would understand the meaning from the kanji. Why do they think this? Why, because in the past, loans were written in kanji, not katakana. That’s why Japanese people were able to understand loans from Chinese (and presumably Korean, though this isn’t mentioned).
Too many problems with this theory, however. Most Japanese people weren’t literate until, say, 150 years ago – only the elite few were educated before that – so the masses weren’t taking a look at the kanji when encountering a loan word and thinking, “Ah ha! Based on that radical, it must mean combustion!” They only encountered the loan in speech, but obviously they were able to deal with it, because all these centuries later, those words are part of the Japanese lexicon.
The other obvious flaw in this theory is that many loanwords – as opposed to Yamato kotoba (native Japanese words) – have nonsensical kanji combinations chosen for their phonetic values alone. So even if the people could read, they couldn’t necessarily extrapolate the meaning from it. (And even that assumes that the meaning in Japanese would be identical to the meaning in the target language, something we know isn’t always true. I’ll never forget seeing ooru-maiti ‘almighty’ used as a Japanese adjective, first on a box of Ritz crackers and then on a shop window somewhere. I had to ask around, but everyone I asked said it meant ‘all-purpose’. Clearly not what ‘almighty’ means in English.)
I don’t doubt that the huge number of loanwords can make for confusion, but clearly Japanese people from centuries past were able to incorporate large numbers of loanwords through oral transmission alone. I think what the author means is that loan words aren’t built from Japanese or Sino-Japanese roots, but this is lost in the article because she conflates writing system with sounds. Were people to start writing loans from European languages in kanji again, as they did during the Meiji era, for example, I still think people would be complaining about too many loans.