  We investigate the network model of community by Watts, Dodds and Newman (D.
J. Watts et al., Science 296 (2002) 1302) as a hierarchy of groups, each of 5
individuals. A homophily parameter $\alpha$ controls the probability
proportional to $\exp(-\alpha x)$ of selection of neighbours against distance
$x$. The network nodes are endowed with spin-like variables $s_i = \pm 1$, with
Ising interaction $J>0$. The Glauber dynamics is used to investigate the
order-disorder transition. The transition temperature $T_c$ is close to 3.8 for
$\alpha < 0.0$ and it falls down to zero above this value. The result provides
a mathematical illustration of the social ability to a collective action {\it
via} weak ties, as discussed by Granovetter in 1973.
