I have leapt over Ziporyn's treatment of Zhuangzi in his Ironies of Oneness and Difference because, following on his (and my) discussion of the Laozi, to do so immediately after might be tiresomely repetitive. I will return to that discussion later, however.
Before looking at Xunzi, it might be helpful to give a quick overview of Ziporyn's overall project in this book. It's about how ancient Chinese philosophy attempted to make 'sense' of the human experience in the world. This 'sense' is largely facilitated through the creation of a coherence. Coherence is about uniting the seemingly disparate 'parts' of our experience into an intelligible whole. This can often be seen in attempts to make intelligible the relationship between the assumed "triad" of Heaven, earth and humanity.
Ziporyn uses the ironic coherence of the Daoist vision as a fulcrum to understand the development of various forms of coherence. Non-ironic coherence is seen in Confucius, Mencius and Mozi (though he is only mentioned in passing). Non-ironic coherence believes this "triad" can be understood sufficiently well to provide a template for how best to live. The proto-Daoists responded with the observation that Heaven, in the sense of Dao, cannot be understood at all, and thus our sense of coherence can only be experienced as ultimately incoherent. The "sustainable whole" is that which includes, and indeed prioritizes, the incomprehensible. Our coherence is thus with the ever-unknowable and ever-transforming so that we learn to live without a fixed template of how best to live, but rather with one of spontaneous following along with the flow of life.
Xunzi provides a decidedly negative response to this ironic coherence by means of a re-working of Confucianism. His is a "post-ironic anti-irony", an attempted return to a non-ironic coherence. He takes up some of the nomenclature of Daoist thought ("emptiness", "stillness", "unity") but folds them back into a world view that knows how best to live by understanding the way things actually are. Though he agrees that Heaven cannot be known, he dismisses the idea that it need be. (Perhaps it is as science usually approaches it — entirely intelligible, but beyond our limited ability to know it.) (Confucius never really addressed the issue, and Mencius only marginally so.)
Similar to Xunzi, other Confucian works ("The Great Learning" and "The Doctrine of the Mean") responded to the Daoist ironic-coherence with a non-ironic vision, but one that also attempted more of a synthesis. (I have not yet read this far.) Finally, Ziporyn discusses how philosophies of the Yin-Yang school attempted a final synthesis.
It is thus in the context of the Laozi and Zhuangzi that Xunzi can best be understood.
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