From the model I've developed for all life processes, it becomes clear that we must embrace evil and not fear it. Organisms do this, and any life system. In the model, motivation always leads to some sort of destruction. Introspection on that destruction leads to growth. Such growth can never occur without the destruction.
Motivation occurs from the realization that the insight successfully created growth.
Now, this can also hold true beyond our selves. You could gain Insight from someone else's destruction for instance. Or you then could also grow from someone else's insight. This same process would hold true, then, for human society. Violence, war, disease are all necessary for society to grow.