Hirschman pointed out that for such a pendular pattern to exist, something outside the private interest/public action framework—some “exogenous variable”—must cause these shifts in involvement. The answer he found was disappointment—namely, that people become disenchanted by one mode of thinking and shift to the other. At some point, the growing imbalance between the vices of one mind-set and the virtues of the other reaches a tipping point, as when adding grains of sand to a balance. The pendular reversal can be seen as backlash to excesses of the previous period.
