The Six Types of Kanji: Understanding 六書 (Rikusho)
The Oldest Classification System for Any Writing System -- and Why It's Wrong
In 100 CE, the Han dynasty scholar Xu Shen (許慎) completed the Shuowen Jiezi (説文解字), analyzing 9,353 characters under a six-category framework he called 六書 (liushu; Japanese: rikusho). His postface gave the first formal definitions. Nearly two millennia later, every kanji textbook still teaches these six types -- but modern scholarship has quietly dismantled several of them.
A page from a Song dynasty edition of the Shuowen Jiezi, showing characters grouped under the 言 (speech) radical with their small-seal forms and glosses. Source: Wikimedia Commons.
Xu Shen's Six Categories
The first four describe how characters are formed. The last two describe how existing characters are used.
| # | Chinese | Japanese | Xu Shen's Definition (paraphrase) | Example | Shuowen % | Joyo % |
|---|---|---|---|---|---|---|
| 1 | 象形 xiangxing | shokei | "Draw the object, follow its form" -- 日 and 月 | 山 日 木 | ~4% (~370) | ~13% (~278) |
| 2 | 指事 zhishi | shiji | "Seen, it is recognized; inspected, its meaning is clear" -- 上 and 下 | 上 下 本 | ~1% (~125) | ~1% (~21) |
| 3 | 会意 huiyi | kaii | "Match types, combine meanings to reveal what is indicated" -- 武 and 信 | 休 林 明 | ~13% (~1,216) | ~25% (~534) |
| 4 | 形声 xingsheng | keisei | "Based on a thing, take a phonetic analog and combine them" -- 江 and 河 | 泳 清 語 | ~82% (~7,670) | ~61% (~1,303) |
| 5 | 転注 zhuanzhu | tenchuu | Reciprocal meaning: 考 (examine) and 老 (old) share an etymological root | 考/老 | -- | -- |
| 6 | 仮借 jiajie | kashaku | Borrowing: 來 meant "wheat" but was borrowed for "to come" | 北 來 | -- | -- |
Shuowen counts from statistical analyses of 9,353 entries. Joyo counts from Kanji Portraits analysis of all 2,136 joyo kanji (2021). Categories 5--6 describe usage, not formation, so they have no exclusive character counts.
The numbers tell the story: phono-semantic compounds dominate at every scale. In the Shuowen, 82%. In the full CJK Unicode block, over 90%. The lower 61% in Joyo reflects a curriculum design choice -- elementary schools front-load pictographs and compound ideographs because they are more visually intuitive for children.
The Reclassification Debate
Here is where it gets contentious. Xu Shen's own canonical examples of 会意 (compound ideographs) may not be what he thought they were.
| Character | Traditional Class | Modern Reanalysis | Evidence |
|---|---|---|---|
| 明 (bright) | 会意: 日 sun + 月 moon | 形声: attested variant 朙 has 囧 (window) as phonetic | Oracle bone forms show 囧 + 月, not 日 + 月 |
| 信 (trust) | 会意: 人 person + 言 speech | 形声: 人 *njin is phonetic for xin *snjins | Phonological reconstruction matches |
| 武 (martial) | 会意: 止 stop + 戈 spear | 形声: 止 may serve as phonetic in Old Chinese | Boltz (1994) argues phonetic origin |
| 友 (friend) | 会意: two hands together | 形声: possible phonetic derivation | Debated; paleographic evidence unclear |
William G. Boltz's The Origin and Early Development of the Chinese Writing System (1994) made the strongest claim: no ancient characters were genuine compound ideographs. Every multi-component character, he argued, originated as a phono-semantic compound, with the "semantic" reading being a later folk etymology imposed after the phonetic connection was lost. Under this analysis, the 会意 category nearly vanishes, and 形声 absorbs it.
This remains contested. Christopher Button has shown that some of Boltz's phonetic reconstructions rely on readings otherwise unattested. The consensus, insofar as one exists: the true 会意 set is smaller than Xu Shen thought, but not zero.
Phonetic Components: How Reliable?
If ~80% of kanji are phono-semantic compounds, how often does the phonetic component actually predict the on'yomi?
| Reliability Tier | Match Type | Approx. Rate |
|---|---|---|
| Exact match | Phonetic predicts on'yomi perfectly | ~67% of keisei kanji |
| Partial match | Same consonant or vowel pattern | ~15% additional |
| No useful signal | Historical sound change has obscured link | ~18% |
Based on analyses by Hamilton (2013) and The Kanji Code's review of 150 phonetic components across 2,136 joyo kanji. Reliability is highest for right-side (tsukuri) and bottom (ashi) phonetics, lowest for top-left enclosures.
The practical implication: learning ~120 high-reliability phonetic components lets you predict the on'yomi of roughly two-thirds of all joyo kanji on sight. That is not a mnemonic trick. It is how the characters were engineered.
The Outlier Linguistics Critique
Outlier Linguistics raises a deeper objection: the six-category system reflects Han dynasty cosmology, not linguistic science. The number six was chosen to fit the Yinyang Wuxing (陰陽五行) philosophical framework. Xu Shen, working without access to oracle bone inscriptions (rediscovered only in 1899) or systematic phonological reconstruction, made the best categories he could with incomplete data. Modern scholars like Tang Lan have noted that the categories never had clear-cut definitions, and many characters resist unambiguous classification.
An annotated Shang-dynasty oracle bone inscription (Heji 29990 / 30174) recording a divination about rain — the kind of primary specimen Xu Shen never saw, and which forced 20th-century paleographers to revisit his classifications. Source: Wikimedia Commons.
If you want to inspect specific characters, our kanji dictionary records each entry's components and the Kanji Atlas renders the decomposition graph — the practical tool for spotting phono-semantic patterns at scale.
Parallels in Other Writing Systems
The rikusho is not unique. Egyptian hieroglyphs developed a strikingly similar tripartite classification: logograms (a sign depicts its referent), phonograms (uniliteral, biliteral, triliteral signs used for sound), and determinatives (silent semantic classifiers appended to disambiguate homophones). The determinative functions almost identically to the Chinese radical in phono-semantic compounds. Sumerian cuneiform independently evolved the same pattern: logograms, syllabograms, and determinatives. Mayan glyphs combined logograms with phonetic complements. The convergence suggests that any script encoding a large word eventually gravitates toward phono-semantic compounding -- the same structural pressure that made 形声 the dominant category in Chinese.
References
- Xu Shen, Shuowen Jiezi (説文解字), 100 CE. Postface definitions of the six categories.
- Boltz, William G. The Origin and Early Development of the Chinese Writing System. American Oriental Society, 1994.
- DeFrancis, John. The Chinese Language: Fact and Fantasy. University of Hawai'i Press, 1984. Chapters on the "ideographic myth."
- DeFrancis, John. Visible Speech: The Diverse Oneness of Writing Systems. University of Hawai'i Press, 1989.
- Outlier Linguistics. "Liushu and Categorical Thinking." outlier-linguistics.com/blogs/chinese/liushu-and-categorical-thinking.
- "Formation Types of Educational and Joyo Kanji." Kanji Portraits, 2021. kanjiportraits.wordpress.com.
- Hamilton, Natalie. "Identifying Useful Phonetic Components of Kanji." 2013. academia.edu.
- "Chinese Character Classification." Wikipedia. en.wikipedia.org/wiki/Chinesecharacterclassification.