Gěng Dìngxiàng 耿定向 (1524–1596) was a senior Wànlì official and a major Tàizhōu xuépài 泰州學派 thinker. Zì Zàilún 在倫 (also Zǐchéng 子承), hào Chǔtóng 楚侗, later self-titled Tiāntái 天臺 (whence his honorific Tiāntái xiānsheng); posthumously Gōngjiǎn 恭簡 (variant Gōngsù 恭肅 in some sources). Native of Huángān 黃安 (separated from Máchéng 麻城 county in Húguǎng during his lifetime — Gěng himself was instrumental in the administrative split). Jìnshì of Jiājìng 35 (1556). His official career rose from Xíngbù zhǔshì through Yùshǐ, Tàipúsì shàoqīng, Yòufùdū yùshǐ, Xíngbù shìláng, Yòudū yùshǐ, and Hùbù shàngshū (Minister of Revenue, 1586); he retired with the shàobǎo 少保 honorific.
Intellectually, Gěng studied under Xú Yuè 徐樾, a direct disciple of Wáng Gěn 王艮, founder of the Tàizhōu school — making Gěng a second-generation Tàizhōu figure. With his younger brothers Gěng Dìnglǐ 耿定理 (the most radical xīnxué enthusiast of the three) and Gěng Dìnglì 耿定力, he constituted the so-called Gěngshì sānjūnzǐ 耿氏三君子 of Huángān. His position within the Tàizhōu spectrum is moderate-orthodox: he sought to integrate the experiential liángzhī of the Wángmén tradition with rule-keeping Confucian moral conduct, against the more antinomian readings.
Gěng is best known to intellectual historians as the principal lifelong adversary of Lǐ Zhì 李贄 (Lǐ Zhuówú, 1527–1602). Lǐ Zhì had been a close friend and intellectual ally of Gěng’s brother Gěng Dìnglǐ; after Dìnglǐ’s death in 1584 the relationship between Lǐ Zhì and Gěng Dìngxiàng broke down into an open polemic — the famous GěngLǐ lùnbiàn 耿李論辯, played out in the Yǔ Gěng Sīkòu 與耿司寇 letters preserved in Lǐ Zhì’s Fénshū 焚書. The dispute is now read as a definitive late-Míng confrontation between rule-bound moral conformism (Gěng) and individual-moral radicalism (Lǐ Zhì). For Lǐ Zhì, Gěng Dìngxiàng became the very type of the jiǎdàoxué (false moralist); for Gěng, Lǐ Zhì represented the destructive antinomian extreme of Tàizhōu thought.
Gěng’s writings transmitted in the Kanripo corpus include the Xiānjìn yífēng 先進遺風 KR3l0087 (with Máo Zài’s supplements) — a Shìshuōxīnyǔ-tradition collection of moral-exemplum anecdotes of mid-Míng officials, designed as an intervention against the corruption of the Jiājìng — Wànlì court — and the Shuòfǔ bǎojiàn yàolǎn 碩輔寶鑑要覽 KR2m0072. He is the subject of Míng shǐ juàn 221 (with his brothers) and the standard place in Huáng Zōngxī’s Míngrú xuéàn 明儒學案 is juàn 35 (Tàizhōu xuéàn 4).