Male dogs in a pack want to be alpha-dog, and fight to get there. Male politicians, to include the marginally female, want to be alpha-pol and fight, scratch, claw, lie, cheat, and steal to get there.
Politics rewards the unprincipled and truculent, and thus those most likely to start wars. A fairly small number of these pathologically combative people decide whether a country of three hundred million go to war with another that most of the population has never heard of.
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