Do native speakers think of 固い・堅い・硬い as homophones, or as the same word?


Japanese dictionaries often give distinguish among meanings for homophonous
words with related meanings that have different kanji representations, such
as:

  * 固い・堅い・硬い (see, for example, [the 大辞林 entry](http://kotobank.jp/word/%E5%A0%85%E3%81%84%E3%83%BB%E5%9B%BA%E3%81%84%E3%83%BB%E7%A1%AC%E3%81%84) for these words)
  * 柔らかい・軟らかい
  * 飲む・呑む
  * 渇く・乾く

My intuition is that all three forms of かたい are really "the same word" in a
native speaker's mental lexicon, and that a native speaker will choose a given
representation from 固い・堅い・硬い in writing so as to provide added meaning. Is my
sense correct here, or do native speakers actually regard 固い・堅い・硬い as three
different words?




It is exactly as you suspect. It is totally illogical to consider 固い・堅い・硬い,
for example, to be three different words and here is why.

Whenever you are dealing with a kun-reading word, you need to remind yourself
that it existed when Japanese was merely a spoken language. We had no way of
writing 固い・堅い・硬い or even かたい. All we had was the sounds "katai". Then we
encountered the Chinese and the rest is history.

The vast majority of homonyms in Japanese are found in words of Chinese
origin.




It is exactly as you suspect. It is totally illogical to consider 固い・堅い・硬い,
for example, to be three different words and here is why.

Whenever you are dealing with a kun-reading word, you need to remind yourself
that it existed when Japanese was merely a spoken language. We had no way of
writing 固い・堅い・硬い or even かたい. All we had was the sounds "katai". Then we
encountered the Chinese and the rest is history.

The vast majority of homonyms in Japanese are found in words of Chinese
origin.

