But this disregards the dynamism that is central to acquiring knowledge. Once we understand "human nature" if it at all meaningfully exists, this also opens the door to manipulation, which destabilizes the whole enterprise to begin with.

It's easy to get caught up in your own social environment and to confuse the nature of the people around you as being representative of human nature in general.

In order to decide what is the best society, we need to know what is good for human beings, and this depends in part on human psychology. Furthermore in order to have such a good society, we need to get people to behave well, and in order to decide how to most effectively attempt to do that we need to understand why people behave in good or bad ways, and again this depends in part on human psychology.

The question then is what is human psychology, including what is universal about it and in what ways it varies, as from person to person or culture to culture, all as relevant to the questions of what is good for human beings and why they behave as they do, good or bad.

These are complicated matters, but I think they are considerably answered by looking at basic human needs, such as Maslow's need theory, and also basic human cognitive abilities.

Civilization (so far) depends on the principle of a monopolizable surplus which allows an elite to mobilize lower ranking elements for games of war and power across geographical distances and temporal distances that would be impossible for HnG societies (bound by the non-monopolizable bounty of the land and the lifestyles possible in such lands)+.

An "evil" or "megalomaniac and sociopathic" society in HnG can only extend as far as their adaptive mode of production. Who can gather all the wild fruits of the earth and deny his brother the bounty?

An "evil" agarian society can mobilize the monopoly surplus to cajole and punish societal elements far beyond the "natural" borders any HnG tribe would've been able to maintain and into torturous decades and centuries.

+ - I've read about a few HnG societies where class structures arose because they had some sort of natural monopoly position; crossroads of a regional trading route or salmon run bottlenecks. But the important part is that monopolizable resources "alter" human nature and society.