With its notions of consensus and harmonious interaction by different groups, social capital is in some senses the practical tool to achieve social cohesion’ (Zetter et al., What makes social networks even more interesting, however, is that they also have implications for bystanders. So while one can point to no end of studies in which a variable that is asserted to proxy for social capital has some effect on individuals or groups, it is very difficult to treat the finding as establishing a causal role for social capital.