How much does it matter today who started the first world war? Daniel Kahneman says something to the effect that it isn’t particularly fruitful to look for which party to blame in a dispute as each party will be biased to believe that it is right, that it was injured,that the others are to blame. Taking sides would then just be the equivalent of entering into the fray, rather than trying to pull the combatants apart. In a second stage, which is the stage of trying to resolve the causes of the conflict, discussion of the merits of the situation may be relevant, but typically we just need to move on because its hard to get people to accept they have been wrong. Its much easier for them to accept they have been defeated.