The white horse paradox is the most famous. but Gongsun Long's philosophical system has a deeper foundation in his Jianbai lun You see its whiteness with your eyes and feel its hardness with your hands. Do you ever perceive hardness and whiteness together, in a single unified act? Gongsun Long argues you do not: sight yields whiteness but not hardness; touch yields hardness but not whiteness. The two attributes are therefore genuinely separate entities, each a universal in its own right, that happen to co-inhere in this stone without becoming identical to it or to each other.
This is Gongsun Long's realism about universals, sometimes called extreme realism or Platonic realism (though developed independently). Universals like whiteness and hardness have a kind of freestanding existence: they are not reducible to the individuals that instantiate them, and they can be grasped independently. This view underlies the white horse paradox: "horseness" and "whiteness" are real, independent universals. A white horse combines them, but neither universal is the same as the combination.
The Zhuangzi, a near-contemporary text, mocks Gongsun Long for these doctrines: "To use a horse to show that a horse is not a horse is not as good as using a non-horse to show that a horse is not a horse." This is not merely ridicule. Zhuangzi's point is that getting tangled in abstract names misses the fluid, undefinable nature of reality, the Dao. The argument between Gongsun Long and the Daoist tradition is therefore a deep metaphysical dispute: does reality have a stable conceptual structure that careful naming can track, or does naming always distort a reality that overflows all categories?
Modern philosophers have found Gongsun Long surprisingly prescient. His distinction between the extension of a name (the set of things it picks out) and its intension (the concept or attribute it expresses) anticipates Frege's distinction between Bedeutung and Sinn. His worry about substituting compound concepts for simple ones maps onto debates in contemporary formal semantics about compositionality. The white horse paradox is not a curiosity of ancient China, it is a genuinely hard problem about how language, thought, and reality relate.
For Confucians, Gongsun Long's program was dangerous: if "white horse" is not "horse," then "correct" names become slippery, and the moral-political order built on zhengming (rectification of names) seems to collapse. Xunzi directly attacked the School of Names for generating sophistry that confused the people rather than stabilizing social language. The tension between linguistic precision and social stability runs through Chinese philosophy of language as a permanent fault line.