Under ancient Jewish law, if a suspect on trial was unanimously found guilty by all judges, then the suspect was acquitted. This reasoning sounds counterintuitive, but the legislators of the time had noticed that unanimous agreement often indicates the presence of systemic error in the judicial process, even if the exact nature of the error is yet to be discovered. They intuitively reasoned that when something seems too good to be true, most likely a mistake was made.Some new research has some quantitative evidence.
The paper argues:
We now consider a different example, drawn from cryptography. An important operation in many protocols is the generation and verification of prime numbers; the security of some protocols depends upon the primality of a number that may be chosen by an adversary; in this case, one may test whether it is a prime, whether by brute-force or by using another test such as the RabinMiller [22, p. 176] test. As the latter is probabilistic, we repeat it until we have achieved the desired level of security ...No, there are hardly any cryptographic protocols that depend on the primality of a number chosen by an adversary.
The paper gives the argument that repeated tests do not increase security as much as one might naively think, because the computer might be malfunctioning. It is a very weak argument.
Nevertheless if someone tells you than something is known for sure, with no error estimates, you should have some skepticism. Scientific claims normally come with error estimates.
Update: Here is a New Yorker article on the problems with eyewitness identification.
Eyewitness identification is unreliable. So if there are 10 eyewitnesses, and they all positively identify the accused, then I guess I should be suspicious. It is more likely that there was undue influence, than that they all became independently sure of what they saw.
This concept can be applied to a lot of other subjects, like global warming. If someone tells you that there is a consensus about what will happen in a century, be suspicious. They could be right, as eclipses can be predicted like that.
But if they tell you that the effects of global warming are uniformly bad, they are lying. Nearly all changes like that have a mixture of good and bad effects. You can only come to a judgment if you have balanced the good against the bad.
Most people are willing to come to conclusions after listening to one side of argument. This is especially true about the Left, as they insist on news and info that is slanted towards their views, and they refuse opposing views.