If a person disagrees with Diamond's thesis in Guns, Germs, and Steel, what factors could they cite as important in the development of civilization?
There are a number of factors that could be cited as important in the development of civilizations. Diamond has responded to many of these arguments, but they can still be made.
For the original rise of civilization, we can cite the need for large-scale irrigation projects. Many civilizations arose along rivers that could be used to irrigate agricultural land, but only with a great deal of effort. In order to harness these rivers and use them productively, people had to work together. This ended up creating situations where people had clear incentives to work together and to obey a central authority.
For the subsequent success of some civilizations and the lack of success of others, we can look to culture and/or religion. Even if we accept Diamond’s idea that Eurasia had advantages over other areas of the world because of geography, we can still say that cultures matter when it comes to determining who succeeds and who does not. Diamond, for example, argues that China failed because its geography made it too easy for one political entity (the Chinese Empire) to dominate the region. But we could just as well argue that China failed because of some fatalistic and passive aspect to its culture and religion. We can argue that Confucianism emphasizes respect for the past and staying in one’s place in society while Protestantism emphasizes the individual and hard work. This, contrary to what Diamond says, can be seen as an important factor that contributes to the success of some civilizations and the failure of others.