One is the reinforcing loop. One party in a system takes an action which is perceived by the other as a threat. The second party takes an action to defend itself against the perceived threat. That reaction is perceived as a new threat by the first party, which then takes further steps to defend itself. Say there is a village, with some meadow land held in common.
Villagers graze their cattle on the common land.
One villager buys more cattle, grazes them there, and makes more profit for himself. Another villager tries the same thing, and another. Soon the pasture is overgrazed, and all the cattle are starving.