Yesterday I watched a documentary about Israel’s secret services. It struck me how the successive leaders of the organization, all in favor of peace and dialogue even with the most inflexible enemies, become immediately calculating when lives are at stake.

The leader of a terrorist cell is inside a building with his family. There’s a missile trained on them. But there is the matter of the neighbourhood. It’s an inhabited neighbourhood. There is a risk that innocent people will lose their lives.

“How many?” That’s the question these men ask. What are they trying to determine? They are trying to understand if today’s innocent victims will be more or less than the number of innocents that future terrorist attacks may claim.

It is a given that innocents will die – fathers and mothers, sons and daughters, brothers and sisters. The question is: will pulling the trigger kill less today than would die tomorrow?

Its math.