Prof. John DeFrancis’ View on radicals
It is important to understand that the term radical is a misnomer. The word Radical comes from radix or “root”. Chinese radicals are not the original heart of a word, but they were added later to another element that was phonetic. DeFrancis prefers using the term signific. These significs came into play as a way of “disambiguating” words using the same phonetic element.
In written English, homophonous words are often distinguished as a result of historical changes in pronounciation and our resistance to reforming spelling to be in line with speech.
Prof. DeFrancis gives an example of this process in Chinese using the words 'reign' and 'rain'. He asks the reader to imagine using the same phonetic element for both words. Normally, context would be enough to tell which word was intended in any given sentence. But, there would be sentences where it would be difficult to determine which was intended, e.g. The X lasted for 40 days. (Where X is a phonetic pronounced reyn).
Then, to tell them apart a water radical (san dian shui) would be added to the word rain, and the person radical or maybe the king radical would be added the phonetic to create the word for reign.DeFrancis' view is that Chinese characters are basically phonetic. He gives a table on page 129 of his book The Chinese Language - Fact and Fantasy which shows that only 3 percent of all characters are pictographic, simple indicative or logical aggregates. The other 97% are xing sheng or determinative-phonetic compounds. He compares how closely the determinative side matches the semantic nature of the particurlar character with how closely the phonetic element matches the pronunciation of the character.
形聲(S声) xíng-shēng n. 〈lg.〉 semantic-plus-phonetic
三點水[-点] sāndiǎn shuǐ (氵)