A second type of heterogeneity could be in the benefits the public good confers on
residents. For instance, farmers with large plots of land have more to gain from an
irrigation canal, families with several children have more to gain from a local public
school than single-child families, people with pre-existing medical conditions might
benefit more from a local health center. In many cases, the rich will have less to gain
from public provision of education and health, since they are the ones who can best
access private provision of such services. In theory, having greater inequality of benefits
can make people less likely to contribute towards it. However, this effect can be reversed
at high levels of inequality: if one person expects to gain almost all the benefits (e.g. if
there is only one farmer in the whole area), he will be motivated to bear the whole cost.
Third, a group can be socially heterogeneous in terms of religion, language, caste
or ethnicity. This can lead to differences in preferences over public goods (e.g. each
person wanting the medium of instruction in the school to be their mother tongue). It can
also lead directly to less effective collective action due to increased communication costs
across different social categories, a lower degree of trust or a lower degree of altruism
towards members of a different social category. Socially homogeneous groups may also
be able to monitor their members’ contributions towards the public good, and use social
sanctions to achieve high contributions. Such channels predict worse outcomes when
society is divided into several different social groups. An alternative possibility is that
social tensions are maximized when there are two large groups rather than several small
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groups, and hence increasing heterogeneity might even help in achieving greater social
cohesion.