Machine tolerance

In his 1981 definition of the Transmission Control Protocol, Jon Postel stated:

TCP implementations will follow a general principle of robustness: be conservative in what you do, be liberal in what you accept from others.

The second clause has been generalized into the robustness principle (aka Postel's Law):

Be conservative in what you do; be liberal in what you accept from others.

The long-term impact of that law is to reduce the impact of bad behavior as long as there is a large and varied number of machines that keep things flowing. Every step of the way, each machine filters out or fixes invalid input, to the extent it makes sense. If errors are logged, and used in a feedback loop to the offending data sources, we witness an average trend towards increased tolerance and positive self-correction.