Nature vs. Nurture
Is human nature inherently violent or musical?
The cause of human aggression and violence is a philosophical argument that stretches back hundreds of years, and which sharply divides students of human nature even today.
Do you believe that humans are naturally peaceful but corrupted by modern society? This "Noble Savage" view was popularized by French thinker Jean-Jacques Rousseau in the 18th century, and places the blame for modern violence squarely on the shoulders of human culture, rather than human nature.
The Englishman Thomas Hobbes believed otherwise, however, and famously claimed that human life in a state of nature was "solitary, poor, nasty, brutish, and short." Human civilization pacifies our violent nature, not the other way around.
And finally, the 20th century filmmaker Stanley Kubrick believed that human violence was caused by a big black rock.