Does democracy really work well in tribal cultures?
That's debatable.
Robert Putnam, author of Bowling Alone, claims that there is a need for social capital in order for democracy to work.
Eg, networks in the local community in form of choirs, fraternal clubs, et al.
And there's not a whole lot of tradition of that in eg Africa.
That's why I'm pretty pessimistic about a long term democracy working in Afghanistan.
What kind of foundation is there for democracy?
I'd say pretty much none.
You would need to start up sports clubs, choirs, social clubs (dance halls?), et al. And several other things in order to sort of kickstart a foundation while "building" it from the top as well.
Sorry for getting off topic a little, you posted a very good question IMO.
