Banality of good
The banality of good, along with it's corollary, the malignancy of evil are concepts of Christian ethics wherein evil deeds carry much more weight than good ones. This truth can be observed in creation in that order is precious and delicate, but that destruction and chaos are easy to achieve. The banality of good underlies the Christian concept of sin. The Christian doctrine of the fallen nature of mankind is often misunderstood to mean that mankind is "more bad than good"; in reality it means that no matter how good people behave, any sin, because of it's malignancy, poisons everything. The Bible teaches that all people have sinned and are falling short of the 100% standard required of them (Romans 3:23). Since no-one is able to meet this standard, all humans are equally guilty before God of "missing the mark". The pride of people who see themselves as "righteous" is therefore misplaced. Because of the banality of good, the only appropriate posture towards one's own goodness is humility.
The banality of good also means that actions, even if they are undertaken with the best of intentions, are capable of doing unintended harm. The reality of the principle of unintended consequences in ethics is that frequently the results of an action have negative ramifications because of the banality of good and the malignancy of evil. This is behind the concept of the concept of the total depravity of man; every action bears the stain of sin, since it is therefore not totally pure, it is tainted and poisonous.
Contributing factors to the banality of good include the world's inherent complexity, human stupidity and self-deception, and the law of cause and effect, where small, apparently insignificant changes can have far-reaching effects (e.g., the butterfly effect).
Wisdom is better than weapons of war,
but one sinner destroys much good.
Dead flies make the perfumer's ointment give off a stench;
so a little folly outweighs wisdom and honor.
"The toil of all that be
Helps not the primal fault
It rains into the sea
And still the sea is salt"
- A. E. Housman
Analogies and examples
Drinking water is necessary for life, but drinking poison results in death. Imagine a glass of pure water and one of pure poison; only the pure water is drinkable, but any mixture of the two is undrinkable. Whether your glass contains only one drop of poison, or if it contains 50% or 100% poison, it's result is the same, the drinkers will end up equally dead. A small amount of poison can contaminate a well, but a vast amount of water is required to dilute it to the point of safety, and no amount of dilution can truly remove the poison.
"It takes many good deeds to build a good reputation," Benjamin Franklin is quoted as saying "and only one bad one to lose it." By the same token, parenting and other deep relationships rely on consistent good deeds to succeed. How often has a relationship or someone's self image been crushed by careless, unkind words? Many words and many years of affirmation and positivity can be wiped out by a brief moment of anger. Although apologies can be given and forgiveness granted, those words can never be unsaid and the seeds of doubt and mistrust that go with them can never be completely removed.
It is far easier to destroy than to build - a house that took months to build can be bulldozed in a few hours or blown up in a few seconds.
Inserting characters at random into computer code, or amino acids into DNA is far more likely to result in errors than in benefits. This is a feature of ordered systems, the order is fragile and exact, there are far more ways to break something than to fix it.
The question is often asked: why is all the news on TV bad? Bad news is more common than good because of the banality of good. If you have a wonderful interaction with your co-workers on a daily basis, laughing together, enjoying meaningful interactions and being a productive team, this could go on for years without it attracting attention, however the one day that someone comes to work and shoots someone, or commits suicide will be of great importance to the local community and attract greater attention than all the wonderful days that came before. This is a natural element of human life; having a great day is nice, but survival dictates that mortal threats command our immediate and full attention.
Within physics, The second law of thermodynamics holds that within a given system, overall [entropy] or "disorder" will always increase until it reaches a state of maximum entropy. This physical law, is parallel to the principle of the banality of good in that every action undertaken to increase order locally inevitably does so at the expense of order elsewhere, so that entropy is maintained and the second law remains true.
In a branch of mathematics known as "game theory," the classic case of "the prisoners dilemma" shows why two purely "rational" individuals might not cooperate, even if the best overall outcome would be for each of them to do so.
An understanding of the banality of good (and the malignancy of evil) leads the farmer to be skeptical of biocides which are intended to deal with a specific problem, but often end up creating problems bigger than the original issue they were intended to address. Within the fields of medicine and bio-ethics, a principle precept is Primum non nocere or first, do no harm. This principle which is taught as a fundamental to all healthcare students and is an element of the hippocratic oath, is based on the understanding that sometimes actions taken with good intentions result in great harm because of the banality of good concept. Despite being widespread, this principle of "do no harm" is often marginalized with modern medical practices such as chemotherapy and antibiotics, just as in earlier practices such as blood letting, and lobotomies, where the "cure" sometimes as bad as the disease.