Jonathan Barnes has written an interesting review of The Way and the Word: Science and Medicine in Early China and Greece by Geoffrey Lloyd and Nathan Sivin about why Chinese science and philosophy were so different.
But second, "the very adversariality of Greek modes of inquiry seems to affect also the content of theories." Just as in the particular case of Plato, "the form of his writing affects its philosophical content,' so in general the manner of Greek philosophising determines its matter. After all, "the great variety of Greek cosmological accounts is to be expected, in view of the systematic competitiveness of Greek philosophy and science."
The cosmologist must sell his wares in the intellectual marketplace; and if he is to outsell his rivals, he had better put a few novelties in his window. Not only that, he must talk up his own goods and talk down those of his rivals. Hence, on the one hand, the facts of Greek intellectual life "favoured systematically exploring the arguments on both sides of fundamental questions" (in order to prove your adversaries wrong), something which "may well have contributed to a readiness not merely to air but to maintain the contradictory of what might pass as a commonsensical view".
By contrast, the writers argue, China didn't have as much of an intellectual marketplace.
In China there was no raucous marketplace. The Chinese were generally writing for the emperor. Hence they "did not feel a need for incontrovertibility, the driving force in... Greek investigations". Rather, "what corresponds in China to the Greek authority of demonstration was the authority of sagely origin", so that "scientific pursuits in China... did not aim at stepwise approximations to an objective reality but at recovery of what the archaic sages already knew".
Moreover, writing for the emperor's eyes "encouraged precision in moral, social and political categories, but it did not motivate an equal fastidiousness with regard to the foundations of knowledge"; and at the same time, in China, "overt, reciprocal polemic of a kind that might have pushed epistemological problems to the fore was rare".
As Barnes points out, and apparently even the authors acknowledge, when it comes to complex series of human events stretching over centuries history is rarely so simple that a single explanation will explain a difference in outcomes. There was competition in China by scholars to get funding by noble men. Chinese scholars did have incentives to argue. But perhaps not just bureaucreacy but culture as well may have discouraged in-your-face argument. Or did bureaucracy of the imperial Chinese sort create the culture that discouraged public debate in the first place?
Other factors could have been at work as well. Picture a clever useful idea appearing by chance in one culture and not another and assume that considerable barriers existed to the transmission of ideas between the cultures. That idea could have stimulated the development of still more ideas from it. The two cultures would then diverge because of a single germinating idea that occurred in only one of them. This is analogous to how a mutation in one isolated population of a species can cause that population to gradually take a different path in pursuing environmental niches and therefore to experience selective pressures in an entirely different way and therefore to develop in a different direction.
It would be interesting to know how many Greek versus Chinese thinkers were self-supporting. In Greece was there a bigger class that was not part of a formal bureaucracy and yet which did not need to work? Was that class more likely to be city dwellers where its members could interact with each other more than would have been the case with affluent farmers? Also, even when the support in Greece came from politically powerful people did the Greek city-state system create less uniformity of thought than the top-down centralized Chinese bureaucracy? After all, one of the arguments made in the debates to explain the rise of the West is that the split of Europe into many competing states led to more competition between states and greater likelihood that any invention or development would find support in at least one state. So maybe competing political autonomous units explain part of the Greek advantage.
Also, how far back did the Chinese imperial system of testing for entrance into the bureaucracy extend? To the extent that learning and mastering an existing standardardized body of knowledge (and I shudder at the thought of the trend toward a standardized US national curriculum) is the route to advancement this would tend to pull people away from engaging in original thought. New ideas do not help one pass tests and advance up the test-based ladder.
Another possible explanation for a difference in Greek and Chinese thought pattern is the nature of the language. See my FuturePundit post Mandarin Language Uses More Of The Brain Than English. If language uses part of the brain that would otherwise be available for other purposes it must have the effect of draining off brain power from those other uses. Though that might have led to natural selection to increase brain capacity to support the demands of the language. Still, if, compared to another language some language uses a different part of the brain it might cause people to conceptualize the world in a different manner.
Update Also see BrainySmurf Adam Morris on this topic. I have doubts about the idea that more unified periods of Greek history produced more ideas. The unity of the Athenian Empire led into the war with Sparta. There do not strike me as having been distinct periods of strife and unity in ancient Greek history. Also, the other city-states that had to align with Athens probably internally did not force their intellectuals to toe the Athenian line in public discourse. But I'm just guessing on that one.