"The reasons behind violence are varied, but a common belief is that criminals act from a breakdown of morals.
But now, researchers in California claim most acts of violence come from a very different impulse - the desire to do the right thing.
Their study argues that many violent attacks are committed as a form of retribution, with the aggressor feeling as though they must commit the crime.
'When someone does something to hurt themselves or other people, or to kill somebody, they usually do so because they think they have to,' Professor Alan Fiske of the University of California said.
'They think they should do it, that it's the right thing to do, that they ought to do it and that it's morally necessary.'
Co-author, professor Tage Rai, of Northwestern University, added: 'Killings and physical attacks are often committed in retribution for wrongs - real or perceived.
The researchers have written a book, Virtuous Violence, which outlines their controversial beliefs.
They say they arrived at their conclusion after analysing a wide array of previous research on violence, including thousands of interviews with violent offenders."
Virtuous Violence is available online to the University of Toronto community