Mou Zongsan has been widely recognized for decades as the most renowned speculative philosopher of the second generation of the New Confucian movement. Sébastien Billioud, complemented in the same Brill series on Modern Chinese Philosophy by additional monographs devoted to Mou by Jason Clower and N. Serina Chan, has authored a superb study of the critical concept of moral metaphysics in Mou's magisterial intercultural revival of Confucian philosophy. The designation “magisterial” is justified because Mou has reshaped the way scholars study the Confucian tradition, and this judgment holds whether one agrees or disagrees with Mou's creative philosophical synthesis of the history of Chinese philosophy.

Mou is notoriously difficult to read because he moves effortlessly between discussions of classical Confucianism, Daoism, Chinese Buddhism, and modern Western philosophy, sometimes within a single page, paragraph, or even sentence. Although it was probably not Billioud's intent, his copious and meticulous translations of Mou's original texts also make his book an ideal guide for those who want to explore and decipher Mou's complicated philosophical vocabulary. Billioud not only translates key texts, he also explains the specific reasoning supporting his translations and hence the translations enhance his impressive ability to provide critical, cross-cultural perspectives on the philological and philosophical context of Mou's work.

Foregrounding Mou's philosophical reconstruction of Confucianism was his passionate, intricate, and sustained engagement with Kant. For Mou, Kant was the paradigmatic philosopher of the modern Western philosophical tradition with whom he should engage in dialogue in order to revive the Confucian Way in the modern world, and Billioud guides us through this comparative aspect of Mou's work with a sure hand.

Billioud begins his study with an overview of Mou's intellectual biography, a necessary task to make sense of Mou's project. By the time Mou was writing his greatest works, from the 1960s to the 1990s, all of his studies contained detailed discussions of Kant, Tiantai Buddhist theory, criticisms of Zhu Xi, and a re-envisioning of the entire history of the Song-Yuan-Ming-Qing neo-Confucian tradition. Billioud excels in his use of the best current European and East Asian scholarship on Mou as well as of contemporary Confucian, Buddhist, and Daoist philosophy. Additionally, Billioud documents the extensive European scholarship on Mou in a bibliography that will be highly useful for English-speaking scholars.

Billioud introduces Mou's moral metaphysics via an analysis of Mou's quest for the “true autonomy of the moral subject” (p. 25). Mou is a very typical Confucian thinker, believing that metaphysics qua ontology commences with the structure of the moral person, a primordial commitment by the intersubjective self as it relates to a person's self-cultivation and engagement with the world. Mou believed that solving this question was precisely the fundamental problem for Kant's philosophical program. In Kant's view, Mou argues, we can ultimately only have a metaphysics of morals and not a moral metaphysics. The reason is that the Kantian self lacks authentic autonomy, because it is always and everywhere constrained by the heteronomous inability of the person to achieve a robust intellectual intuition of things-in-themselves. The aim of Mou's moral metaphysics is to show how, via the intersubjective constitution of the self, a person can achieve intellectual intuition, namely an ability to reflect upon and interact with the world that overcomes the false dichotomy of self and other. In order to explicate Mou's argument for a moral metaphysics, Billioud provides two chapters on Mou's claim that human beings can have a robust form of intellectual intuition, and that this intellectual intuition allows for the axiological discernment, both in theory and practice, of the myriad things-in-themselves that constitute the shared human life-world.

Billioud then proceeds to interrogate Mou's claims that this reshaped Confucian “fundamental ontology” can indeed sustain all the weight of the speculative metaphysical discernment that Mou assigns to it. Billioud, as he does throughout the work, both explains and critiques Mou's philosophy, and he does not hesitate to say when he thinks Mou gets it right and when he perceives minor and major problems of coherence. Billioud then explores Mou's defense of the role of moral emotions as part of the Confucian critique of Kant. In this regard, although Mou is a completely modern cross-cultural Confucian philosopher, he continues the long debate within Confucian thought about the role of the emotions. According to Mou, the emotions allow for an intersubjective concern for and understanding of other persons and the myriad things and events of the world. The book closes by demonstrating how Mou links these intercultural debates to the perennial Confucian search for an effective methodology of self-cultivation. Billioud explores Mou's contemporary rendering of the Confucian habits of the mind-heart as linked to an understanding of philosophy as a way of life and not just an abstract analysis of intellectual history. In closing, it is impossible to do justice in a short review to such an accomplished philosophical examination of the mature work of a great modern Confucian philosopher.