It should be borne in mind, as Scott affirms, that rebellion is one of the least likely consequences of exploitation (1976:192), and that only a collective "shock" or a series of "shocks" of substantial scope provides a reason for a large body of peasants to defensively react or rebel. The resort to defensive actions, he argues, might be related to ecological vulnerability, price system vulnerability, or mono-crop vulnerability (1976:194). In other words, the "brittleness" and "explosiveness" of the agrarian structure, according to Scott, is a product of interacting forces, partly demographic-ecological, partly in response to market forces and partly owing to the growth of the State (1976:196). Popkin adds that in seeking to explain why peasants in colonial Annam eventually overthrew their notables and reorganized their villages, one should not assume that their moral bonds had withered but should "concentrate on the ways in which colonial influences increased social stratification by adding to the comparative political advantages of the notables thus aggravating peasant grievances" and which finally gave way to support to revolutionary movements (Popkin 1979:201). Scotfs contention that in the context of depression in Annam, the continued collection of fixed taxes posed the immediate threat to subsistence (1976:132), would not contradict Popkin's conclusion.