Aymeric wrote:Well from my own experience (I still have a great deal to learn) I would say that it is useful to learn their meaning, and anyway even if you don't learn it intentionally, you will with practice.
It's useful because you can find lots of words that are a combination of two frequent characters, but that you can't find in the most common dictionnaries. So unless you know the meaning of the two characters and guess the general meaning of the word, you won't be able to understand it.
More importantly, a lot of words have almost the same translation in English while they must not be mixed up and have big nuances.
Just the first example that springs to my mind : 规律，规定，规则，规矩. These four words can be translated by "law" or "rule", and this is what you will find in dictionaries. Actually each of them is different from the others, and you can have a feel for these differences only by knowing the exact meaning of 定，律，则，and 矩.
Mixing up these words is perceived as incorrect, so obviously it's necessary to know their exact meaning.
I agree with Aymeric. To take his example, words like 规律、规定、规则、规矩 could appear to be somewhat similar to learners of Chinese as they all more or less mean "law", "rule", "regulations", etc.
This is actually the thing which makes advanced Chinese even more complex than intermediate Chinese (I'm not trying to scare people away
); the fact how you cannot basically translate a given word of English or any Indo-European language (to talk about what I know myself) into Chinese based on a clear and accurate corresponding table. This is also why, to some end, bilingual dictionaries become rather useless at some extent; because the word in itself is now translatable in a given context if you don't know yourself, or have read yourself of this word used in a specific context. This is to me what makes Chinese a difficult language for foreigners: how, in order to master a given jargon of Chinese, you have to be aware of the words used in it.
This is not easy, and this does not come naturally. One has to study Chinese seriously to get such a feeling, and often this feeling is not enough. You have to know which word is used in which context and this only comes through an unconscious appreciation of the volume of data you had below your eyes so far; to give a concrete example, who would know which one of the words Aymeric gave for "rule" is used with traffic (交通), to mean (I'm not even sure about the English term) "transportation regulations"? Through my experience, I can state that the accurate word is 规则; not because the meaning/etymology of the other words sound wrong to me, but because this is the word I saw many times along with traffic: 交通规则. For instance, about how a school/university or even any sort of administration should be run, I would see the word 规定 used the most often. I am not saying the other words would be wrong in such a context; the point is that from my experience I wouldn't see them used. And I believe that my experience is not subjective, but merely the result of having had under my eyes papers/texts/notes/etc from the PRC which used such words in their specified context.
The solution I would give to such a concern is: read, read, read texts in Chinese. Of course I don't push beginners to read complex texts all in Chinese, but the evolution has to follow the same path as for other languages. Except that if English is probably not too picky about which one to use between "traffic regulations", "trafic laws", "trafic rules" (the last one sounds awkward to me, yet this is only a supposition that English is not extremely picky about these), Chinese would be pickier and would already have a determined standard about which word is the best one to be used with traffic.
And this is, I believe, the real complexity with Chinese.
Israel (ישראל / إسرائيل)
Sometimes both characters mean pretty much the same, sometimes the whole expression has little to do with the meaning of component letters, for instance:
could anyone tell me how to put real tone marks?
France (France)
and quite complicated 
)
That "Insert IPA character(s)" can give some tone marks... although the IPA tones and the usual Mandarin tone notations are different. Let's see:
The 3rd tone gives me trouble
North Korea (조선)