Why do we never learn?
Obviously it is difficult to argue that we do nothing in the face of the slaughter of innocent people by ISIS. But we should ask how we got here - by repeating massive mistakes. The history of major interventions in non-European countries in my lifetime is disastrous.
I can as a child remember the Korean War. The North Korean regime testifies the failure of that enterprise. Then Vietnam. Then Afghanistan, where we failed to learn from Russia's failure. Then Iraq, followed by the Arab spring, which has left a chaos of instability across North Africa.
Intervening militarily in complex, factionalised, hierarchical cultures that we do not properly understand is a terrible idea. Not least, the "experts" who are paraded to advise and pontificate in the media on what we should do are discredited. This applies to the civilian pundits as much as the military men.
What should we do? We could try diverting the huge costs of military adventures into diplomacy, education, intelligence and above all investing in the poor communities in which young people are vulnerable to perverted promises of glory.
We should also remember that the perpetrators of monstrosities are someone's son or daughter, probably someone's brother or sister, maybe someone's husband or wife, father or mother. It is said that they are "animals" or "inhuman". We need to assert or core of mutual humanity with them (and everyone in the world) before they plunge into nihilism.