In populace-based, revolutionary conflicts like we are seeing across the greater Middle East in the current decade, "understanding why 'they' fight" is interesting; but I believe it is in understanding why the broader population those fighters rely upon support the fight that is key.

There are many reasons why young men fight. There are many reasons that leaders of fighting organizations use in their public messaging. But these are the tip of the iceberg. The vast majority of the mass behind these types of movements are an aggrieved segment of the population, that like an iceberg, is typically below the surface, not seen, and not well understood.

This is not dissimilar to recognizing that understanding why young men join the Marine Corps is very different than why our national leaders decide to employ the Marine Corps in combat - which in turn is very different than why our nation has a Marine Corps.

Not a perfect analogy, but point is that there are many layers to these things, and the layers that are the most visible and vocal are not of necessity the layers that are the most important to understand and address to move a situation toward some degree of durable stability.