Dai Zhen 戴震 (1723-1777), courtesy name Dongyuan 東原 or Shenxiu 慎修, was a philosopher of the high Qing period 清 (1644-1911). He was a representant of the Anhui branch (Wan pai 皖派) philological school of Confucianism concentrating in early Han period 漢 (206 BCE-220 CE) writings (therefore called Hanxue 漢學) that flourished during the Qianlong and Jiaqing reigns (therefore called Qian-Jia School 乾嘉學派).
Dai Zhen hailed from Xiuning 休寧, Anhui, and was a disciple of Jiang Yong 江永. As a young boy he drafted the Xiaojietu 小戒圖, a chart on self-restriction. He had not only a wide expertise in the classical writings but was also known to be able to memorize all thirteen Confucian Classics and the ancient commentaries to them. In the age of 23 sui, he wrote a study to the chapter on craftsmanship in the book Zhouli 周禮 "Rites of the Zhou", the famous Kaogongji 考工記.
Later on, he moved to Beijing and became a disciple of Qian Daxin 錢大昕 (1728-1804), who admired Dai Zhen's "marvelous talents on the earth" (tianxia qicai 天下奇才). Qin Huitian 秦蕙田 (1702-1764), Vice Minister of Rites (libu shilang 禮部侍郎) asked him to participate in a joint commentary to the five types of rites (jili 吉禮 "auspicious rites", jiali 嘉禮 "excellent rites", binli 賓禮 "guest rites", junli 軍禮 "military rites", and xiongli 凶禮 "inauspicious, i.e. funeral, rites"), the Wuli tongkao 五禮通考 that was later studied by quite a number of contemporary scholars like Ji Yun 紀昀 (1724-1805), Wang Mingsheng 王鳴盛 (1722-1797), Wang Chang 王昶 (1724-1806) or Zhu Yun 朱筠 (1729-1781).
Dai Zhen's own career was not as flourishing as his name. He passed the provincial examination at the age of 39 sui and thereafter failed six times in the metropolitan examination. Only with 52, he succeeded and was allowed to oversee palace examinations (dianshi 殿試) and was appointed bachelor (shujishi 庶吉士) of the Hanlin Academy 翰林院.
Dai Zhen was admired for his excellence in philological analysis of ancient texts, in the field of phonetics as well as semantics. His research focused on personal names, the administrative, legal and ritual systems, astronomy, calendar, mathematics, and historical geography.
The philological school of Qing period Confucianism approached the meaning of the Confucian Classics with the help of analyzing the meaning of individual words and characters which made also necessary a phonetical analysis. Dai Zhen described his scholarly method as explaining the Classics with the help of characters, and the characters with the help of the Classics. The utmost aim of the Classics was to approach the Way (dao 道). Illuminating the Way is only possible by words (ci 辭) and their written expression, characters (zi 字). The instrument of characters is therefore the point from which the study of the Classics has to be begun. The Confucian scholar using this method of explaining the meaning of the Classics must therefore engage in philological studies and go beyond a purely philosophical speculation.
Dai Zhen studied the early Han period primers (mengshu 蒙書, see primary teaching) like the books Fanjiangpian 凡將篇, Jijiupian 急就篇 and Yuanshangpian 元尚篇 that are preserved fragmentarily, but also the famous Later Han period 後漢 (25-220 CE) character dictionary Shuowen jiezi 說文解字. He concluded that the six types of writing (liushu 六書) explained in the Shuowen were the guiding network of characters and the "ferry" to arrange the Classics. Dai's studies on ancient philology surpassed the results of earlier research. In his books Shengyun kao 聲韻考, Shenglei biao 聲類表 and Gushi yilun ba 顧氏音論跋 he divided ancient syllables in 9 types (lei 類) and 25 categories (bu 部) and engaged in a systematic study of the entering tone (rusheng 入聲, see phonology) and the interrelation (duizhuan 對轉) between Yin and Yang syllables (yinyun 陰韻, yangyun 陽韻). He set up a pattern of relation between sounds and characters.
His study Kaogongji tu 考工記圖 analyses the original text of the Kaogongji and Zheng Xuan's 鄭玄 (127-200) early commentary and points out errors in Zheng's interpretation. With the help of illustrations Dai Zheng clarified the textual description of the tools and implements described in this text.
While Dai Zhen brought the Han studies to full expansion, he criticized the highly speculative character of Song 宋 (960-1279) and Ming 明 (1368-1644) period Neo-Confucianism. Neo-Confucianism, he said, was formed by personal views that were in no way based on scholarly evidence from detailed studies in the basic texts. Dai Zhen's own studies as a representant of the Anhui school used basically the same method as the scholars of the Wu school (Wu pai 吳派, with the main representants Hui Dong 惠棟, Qian Daxin and Wang Mingsheng), but he surpassed the frame of philological analysis and developed his own philosophy that was based on his studies of the Classical writings.
Dai's philosophy is exposed in his writings Yuanshan 原善, Xuyan 緒言, Mengzi sishu lu 孟子私淑錄, Mengzi ziyi shuzheng 孟子字義疏證, Yu mou shu 與某書 and Da Peng jinshi Yunchu shu 答彭进士允初書.
Dai Zhen was of the opinion that all things under Heaven consisted of an originary matter (qi 氣) that had been transformed into concrete objects. Matter transformed, spread and developed in a never-ceasing way all objects. This constant movement is the Way (dao) or "pattern" (li 理) of the universe. The result of change is due to the forces of Yin and Yang and the Five Processes (wuxing 五行). Matter (qi) is the substantiation of the Way. The Way, as the principle above the form (xing er shang 形而上), is the state of matter before it resulted in a shape. The "vessel" (qi 器) is the principle below the form (xing er xia 形而下), in which each individual object finds its manifestation. Dai Zhen argued that it is not possible that the principle or universal pattern (li) can exist anyhow before things take shape, as some Neo-Confucians had believed. In his eyes, the universal pattern is like an atomic part of things that cannot exist for its own. The pattern or principle is like rules behind things that control them.
In his book Yuanshan, Dai Zhen stressed that man is by nature inclined to goodness. He thus follows the original assumption of the Confucian philosopher Mengzi 孟子. This is because emotions and desires (qing yu 情欲) are identical to the Heavenly principle (tianli 天理). It is therefore not possible that a man can have emotions that are not shaped by Heaven. With the assumption that the Heavenly principle is integrated in desires (li cun yu yu 理存于欲) he also contradicts the Neo-Confucians who said desires were to be avoided and Heavenly principle, as contrary to desires, to be preserved. His attacks on the Neo-Confucians go so far that he compares their "killing people with the universal principle" (yi li sha ren 以理殺人) with the elimination of men by cruel officials with the help of the law.
Dai Zhen's most important writings are the commentaries to the Confucian Classics Mao Zheng shi kaozheng 毛鄭詩考正, Shijing buzhu 詩經補注, Shangshu yikao 尚書義考, Yili kaozheng 儀禮考正, Kaogongji tuzhu 考工記圖注, Mengzi ziyi shuzheng, and Daxue buzhu 大學補注, his commentaries Fangyan shuzheng 方言疏證, Erya wenzi kao 爾雅文字考, and Shuijing zhu 水經注, the former two on gloss books, the latter on a geographical book, as well as his studies on phonology Shengyun kao and Shenglei biao, his study on the ancient calendar Guli kao 古曆考, and his philosophical book Yuanshan.