A necessary evil is something harmful or that would normally be morally wrong - that must be accepted or tolerated because it is believed to be unavoidable or required to achieve a greater good or to prevent a worse outcome. It is an undesirable but unavoidable part of a situation. It is not to be celebrated.
A or B are both necessary evils. The dilemma itself—having to choose between two necessary evils—is also a kind of necessary evil because it forces you into a harmful situation with no ideal solution.
Being forced to choose between two necessary evils forces you to conduct yourself by a process of elimination, which is inherently very negative - spiritually, biologically, philosophically, psychologically, and morally. For that reason, no matter how much you need to do a harm, it will damage you and plant the seeds in you for doing deliberate harm.
Not all necessary evils carry the same weight—some are less significant than others.
It is possible to go through life and be as damaged by dealing with lesser necessary evils as you would be by bigger ones. The smaller ones mount up to a lot of damage.
The list of necessary evils that you may have to consider gets longer if you have a God to respect and consider.
Life is full of major necessary evils, eg knowledge, responsibility and authority. Each comes with its own burdens and contradictions. These necessary evil are complex and unavoidable parts of existence but remain harmful and harming and sow the seeds of harms we will never discern. Morality itself, and by extension religion when tied to morality, can be seen as necessary evils that must be approached with caution. Recognizing the nature and limits of necessary evils helps us avoid accepting harm that is not truly necessary and guards against being corrupted by false justifications.
All necessary evils are not equal.
Not all necessary evils are equal. One can be a less important necessary evil than another.
Here is a selection of the major necessary evils in life.
Each one is a part of what morality is all about.
Knowledge
Knowing is necessary, for we need truth, and it is up to us to embrace the truth; it is not truth's job to fit us. It won't. It will bounce back hard no matter how much we try to silence or deform it.
The evil side of knowing is that it implies that anything—and in practice, anyone—that contradicts that knowledge is unacceptable. It would be nice if there were an exact match between what we want to believe and what we know. Knowing takes away our freedom to believe anything different. That aspect of it is a necessary evil.
Facts are intolerant in the sense that they contradict, threaten, and oppose errors and don't care about what we want to think. We cannot treat a person basing their work on facts the same as we would a person basing the same work on errors and guesses.
Knowledge is good one way and a necessary evil another.
Creation
The complaint that
firstly, a God made us without our consent, and
secondly, that he put nobody in a context that is ideal or very conducive to flourishing,
is interesting.
If creating us from nothing without caring what we think or would think is degrading, it is even more degrading when we see what kind of creation we are part of and stuck in.
Consent to exist and how to exist would be fundamentally good. It is not possible to give consent, for we can't exist before we exist to say, "Yes, let me be made." It would still mean that our existence would be a necessary evil. It would not be the "very good" of the Bible. The Bible says God made all and was admiring how good it was. God is taking advantage of our inability to agree to be made.
And you can infer consent even if the person does not give it or cannot. Nobody would consent to a life of agony and indignity. A God who does not care about what we would go for does not care about us.
We conclude that even if God was right and kind to make us, and also to make the kind of dubious universe we are in for us, there was a bad side—a necessary evil, if you like.
Free Will
Free will is the belief that we are responsible for our actions and that we cause them, be they bad or good. Free will is great if we do good, but the risk of doing bad gives it two sides. Free will can look like a good but is in fact a necessary evil.
There is no free will to be totally good all the time. It cannot be done. Thus, free will is really more a necessary evil than a great good. It is wrong to celebrate and glorify a necessary evil as a gift from God. You do not celebrate the gun as a necessary evil. What does that say about your attitude to those who use the gun and the people who die?
Responsibility
Responsibility is recognizing how you are involved when something good, bad, or neutral happens. For example, if we knowingly vote a terrorist into power, we share in the responsibility for the evil he or she will do.
Is this partial responsibility? It is, in the sense that other people are involved too. But if you were on your own and you would still vote for him, then you are as responsible as you would be if you were the only voter. The role of others does not diminish or lessen your full responsibility. In fact, you are saying that you need them to get the strength for your true colours to show—thus you are happy that they corrupt themselves.
Imputing responsibility for evil to the agent is a necessary evil. Why? Because it admits the person has bad potential. Because it admits the person may need to suffer and should suffer for doing the wrong things. Even if a person is good, there is still a may. There is still a chance that they may deserve something bad, for you don't know if their goodness is as genuine as it looks.
You are responsible for what evil another human does in this sense. You share a common nature. Thus, what Hitler does is what you would be doing too if you had the same environment and traits.
We find that you are both partly, and in a way fully, responsible for putting the terrorist in power.
Responsibility is seen as a good thing but it is also a bad thing. Thus, it is a necessary evil.
Authority
Authority is treating somebody and something as having the right to tell you to believe or do things you may or may not understand.
Most people think that if an authority is about sincerely trying to represent what is true, then it is a valid authority—even if it is wrong. That is how they can regard the pope as having authority even as they suspect there is no way of telling which religion is true or if one has more truths than the others.
Actually, there is no real authority apart from being right. A Hitler who is secretly insane and acts normal will come across to us as sincere, and that does not mean we can just obey him.
Most people today do not want to be subject to any authority. When they obey, they do it unwillingly. They know that doing good because you are told to is not the same as doing it because you understand why and that you should. Society cannot function without authority, so it is at best a necessary evil.
If you understand as well as or better than the authority, then you should be your own authority. That would be when authority becomes an unnecessary evil. There is a sense in which bowing to authority is hypocrisy. You are the one deciding they are the authority, so it is really your own authority you are following. This point shows that if your own authority is enough, then other authorities are a bad thing. They are unnecessary evils.
The critics say that people's suspicious attitude to authority is bad, for it is essentially a form of opposition to the authority of truth. They say that only those who accept the authority of the truth can be truly free. They must mean that obeying is freedom in the sense that you are free from worse things happening if you don't obey. Without authority, there would only be chaos, and authority risks leading those under it astray or harming them. So it is a necessary evil. That makes this kind of freedom a necessary evil. You are not that free when you have to embrace it.
Many believe that freedoms with conditions are not freedoms at all. Quite right!
Authority is not a proper good but a mixed one, a necessary evil. And so is the freedom we get under it.
FINALLY
Morality is not a good but a necessary evil. The same would be true of God if God is somehow the same as morality. The concept of the necessary evil is a fundamental one. We need to beware of and object to evils that are presented as necessary when they are not. Religion is the perfect example of such an evil, and dallying with it can only corrupt you. We cannot celebrate life without celebrating necessary evil. But that does not mean we should go too far. Religion is refuted.