In 1932, when Einstein attempted to induce Freud to support pacifism, Freud replied that there was no likelihood of suppressing humanitys aggressive tendencies. If there was any reason for hope, it was that people would turn away on rational grounds that war had become too destructive, that there was no scope anymore in war for acts of heroism according to the old ideals.
Freud was partly correct: War (at least between great powers) has become far less likely for rational reasons. But his argument does not apply to terrorism motivated mainly not by political or economic interests, based not just on aggression but also on fanaticism with an admixture of madness.
Terrorism, therefore, will continue not perhaps with the same intensity at all times, and some parts of the globe may be spared altogether. But there can be no victory, only an uphill struggle, at times successful, at others not. ” (Policy Review)