In society it is common for people who get together for work or pleasure to make the same kinds of mistakes. This Error Covariance not only interferes with their activities, it has also caused riots and wars.
This is a serious problem in all aspects of our society, from individual lives through industry to the legislative and the executive powers of government.
In the judicial system upper level level courts often have a panel of judges. If they all tend to make the same mistakes, their decisions are more likely to be wrong. This is true for juries as well. Lawyers on both prosecution and defense sides try to empanel a jury which if they mistakes at all will all make the same mistakes on the side the lawyers represent.
This is a serious problem in legislation and government, where legislators may collaborate to make the make the same mistakes (intentionally or unconsciously). In the administrative side of government, officials are not unbiased and their conscious or unconscious biases may be a result of error covariance among them.
Worse, crowds of people turn into lynch mobs, whether is good reason or not. However guilty someone is, there is certainly no excuse for vigilante action. The same applies to public riots.
Worst of all, people fight wars for little reason and little chance of success. The first World War was a prime example. Thousands died for a few yards of territory they lost and gained again several times. Millions died altogether. Was it really worth it? Few if any historians think it was.
What has the war in Syria accomplished? Nothing. Wars are pointless but people gather on mass to fight them because they are all making the same error, they all think they are worthwhile.
Note that new social technology could be used to solve this problem or make it worse. It could put together teams of people to work together successfully because they have low error covariance among them. Or a dictator could put together police forces or armies to do his bidding by assembling groups of people with a high error covariance among them.
See my old front page for a somewhat technical explanation.