Sentence:  Whether modern, industrial man is less or more warlike than his hunter-gatherer ancestors is impossible to determine....One thing that is <WSD>true</WSD>, though, is that murder rates have fallen over the centuries, as policing has spread and the routine carrying of weapons has diminished. Modern society may not have done anything about war. But peace is a lot more peaceful. 
Meaning of the word marked with <WSD> tags:  Conforming to the actual state of reality or fact; factually correct.