Zero Tolerance
Many of the worst things (by anyone's reckoning) that have ever been done in this world were done by people who were convinced they were acting rationally on behalf of justice and common sense.
How is it possible for well-meaning people to go so far wrong? Simple: they are just too lazy to think. Rather than examine every proposition and judge every case on its own merits, they demand a simple formula for righteousness, a litmus test for good or evil, and apply it universally without further mental effort.
This is the human character flaw behind the notion of Zero Tolerance, which is in turn the origin of evil on Earth. Every time anyone says, "The only acceptable amount of tobacco smoke in our environment is zero," or, "The only acceptable risk of a reactor core meltdown is zero," they are expressing the same sentiment as the person who says, "The only good $X$ is a dead $X$." They have cut themselves off from the responsibility for comparing costs and benefits, from the necessity of making difficult decisions; and the outcome is always disaster. Our "civilization" is crumbling as its foundations are eaten away by the lazy and odious notion that "zero tolerance" is an acceptable basis for personal opinions, let alone an appropriate way to formulate public policy.
