Japanese writing system
The following excerpt is from the article Outline of Japanese Writing System, an otherwise very worthy read:
In English, the relationship between the above words is somewhat obscured by the fact that the concept of water is expressed in three different written forms, i.e., hydr, aqua, and water. In Japanese, on the other hand, although 水 has different phonetic forms, i.e., an on reading of sui and a kun reading of mizu, it has only one form, i.e., 水. The kanji thus provides a visual link that transcends the different pronunciations. This ability of kanji to represent a given meaning with little or no dependence on their pronunciations is perhaps one the most distinctive features of the Japanese script.
While this may be true, I still find it hard to guess the exact meaning a certain japanese word has. This is confirmed by a following paragraph:
Generally, the more common a character is, the more numerous are its meanings and the more complex is the relationship between them. An extreme example is 上 jō ‘up; go up’. This dictionary lists a total of 114 meanings for 上, subdivided into 16 subentries. It has 27 meanings as an on word element, 3 meanings as an independent on word, 17 meanings for 5 kun word elements and 67 meanings for 9 independent kun words. Although 上 is a very long entry and is hardly typical, many characters do have more than ten on and kun meanings combined.
So how can you be sure which meaning you are supposed to give to a character in a random word? I’m sure it gets easier to guess right when the character you’re looking at is less used, but for a beginner such as myself, it’s not a great advantage of kanji. This so-called advantage of using kanji is greatly overrated.
Fortunately it’s not exactly a burden either, like how you don’t have to know all the Latin or Greek roots to understand English. You just look up these unknown words in a dictionary. But saying that it’s easier to guess the meaning of a Japanese word if you know the meaning of several basic kanji is like saying that you can guess the meaning of an English word if you know French.
One thing that does make kanji useful is that the Japanese language has lots and lots of homophones. This is caused by the import of a huge amount of Chinese words, totally ignoring the tone accent and subtle distinctions in the pronunciation. Using kanji in written text makes it very easy to discern between homophones, because they are usually written with different kanji for different meanings.