And yet this is based on an untested assumption that political union is the only way to avoid this.

Furthermore, you could argue that the EU contributed to the triggering of a new Cold War (hot in the Ukraine) by staging a coup of a democratically elected government.

Or at the very least having unelected foreign policy actors (Ashton et al) take ham-fisted actions on behalf of a whole continent.

...or that it has contributed to untold sufferring of an entire generation in the Mediterranean countries due to an ill-conceived currency union.

Given said negative externalities, might it be worth re-visting the premise of the whole endeavour?