We all want to believe that humankind is getting smarter and we won't repeat past blunders. This theory rests on the belief that we can learn the right lessons from our past and cast discredited ideas into the historical garbage bin where they never see the light of day again.
This article in Foreign Policy expores why it is so hard to learn from history and, when we do learn, why some of the lessons are so easily forgotten.
…The tendency to cling to questionable ideas or failed practices will be particularly strong when a set of policy initiatives is bound up in a great power's ruling ideology or political culture.
…When Pentagon officials tell us that increased drone strikes are working, we just have to take them at their word. Maybe they're right, but if they aren't, we won't know until long after the damage has been done.
…Perhaps the most obvious reason why foolish ideas persist is that someone has an interest in defending or promoting them.
…When a country's foreign-policy elite is insulated from failure and hardly anyone is held accountable, it will be especially difficult to learn from the past and formulate wiser policies in the future.
…Last but not least, discredited ideas sometimes come back to life because societies simply forget important lessons about the past. Political psychologists generally agree that personal experiences have a disproportionate impact on our political beliefs, and lessons learned by older generations rarely resonate as strongly with their successors.