Social capital makes democracy possible, and its absence makes democracy difficult as in the US now or impossible as in Afghanistan. This quotation is from Comparative Politics, Using MicroCase Explorit by Michael K. Le Roy.
“Social capital is the reserve of goodwill and trust citizens have toward on another that allows them to engage in democratic behaviors. In a study of Italy, Putnam theorizes that democracy works best when citizens with different backgrounds and perspectives can trust one another. On the face of it, this makes sense. If you generally trust people, you will be more inclined to tolerate election results that do not work in your favor. While you may not agree with the decisions of your government, if you trust that people will not harm you, you are much more likely to allow them to govern if they are properly chosen by the community as a whole. Social capital in and of itself, though, does not necessarily precede democratic behavior. Democracy is usually very risky business if you are part of a group that feels threatened, so a track record of benevolent government and loyal opposition can help to build the social capital necessary for democracy.”