Accuracy, effectiveness and consistency
A rational ethicist lives by the slogan: accurate in beliefs, effective in means, consistent in ends. Our ends should be consistent in the sense that our moral values or ethical principles should not contain contradictions, vagueness or unwanted arbitrariness. In order to be effective in reaching those ends by choosing the best means, our beliefs should be accurate in the sense that they should be in line with reality.
In order to arrive at accurate beliefs, a rational ethicist is a member of the scientific skeptical community by following evidence based science, which is the opposite of pseudoscience. And in order to use effective means, a rational ethicist is a member of the effective altruist movement, because one of the most important ends of a rational ethicist is to improve well-being (decrease suffering, avoid dangerous risks, satisfy preferences) of everyone existing now and in the future.
Consistent ends in ethics are based on our strongest or deepest moral values, emotions and intuitions. However, we are vulnerable to cognitive biases, blind spots and illusions. The existence of optical illusions proves that our senses cannot always be trusted. But neither can we always trust our emotions, intuitions and judgments. In ethics, we have moral illusions: spontaneous, intuitive moral judgments that are very persistent, but they violate our deepest moral values. They distract us away from a rational, authentic ethic. Rational is the opposite of irrational, not of emotional. Our moral emotions and intuitions can be valid and can play an important role, but we cannot always trust them. A rational ethicist wants to avoid cognitive biases and moral illusions, by applying critical thinking in science and ethics.
Avoiding unwanted arbitrariness
A rational ethicist avoids all kinds of unwanted arbitrariness. Arbitrariness consists of picking an element or subset of a given set without using a rule. If you picked an element X from a given set, why did you pick X and not another elements, such as Y? If you cannot answer this question by referring to a rule that does not explicitly refer to X, your choice for X was arbitrary.
Pseudoscience, which results in inaccurate beliefs, is based on unwanted arbitrariness: cherry picking data (arbitrarily selecting some data from the set of all available data), cherry picking studies (arbitrarily selecting some studies from the set of all available studies), referring to arbitrary anecdotes (arbitrarily selecting a story from the set of all stories), inventing ad hoc (‘for here’) rationalizations that only apply to some arbitrarily exceptional cases, arbitrarily giving more weight to some evidence or arbitrarily excluding some evidence, and so on.
Pseudo-ethics, which results in ineffective means and inconsistent ends, is characterized by unwanted arbitrariness as well: arbitrarily excluding individuals by discriminating them, arbitrarily making exceptions for specific situations or persons, arbitrarily formulating or framing moral problems in a certain way so that they can be tackled in an arbitrary way, arbitrarily interpreting vague moral rules, and so on.
Some kinds of arbitrariness in science and ethics is unavoidable. A scientific theory or ethical system cannot simultaneously contain all possible principles or laws. The selection of possible consistent principles from the set of all available principles is always arbitrary. Some kinds of arbitrariness in ethics is harmless or innocent if no-one cares about it. Arbitrariness is not unwanted if everyone can consistently want this arbitrariness and no-one can consistently object to it. You can consistently want something if that what you want is not in contradiction with a consistent set of all the most important things that you want or prefer, such as your strongest moral values. You can consistently object to something if what you want is incompatible with a consistent set of all the most important things that you want or prefer.
The unavoidable and innocent kinds of arbitrariness are kinds that anyone could consistently want. The culprit in ethics is the unwanted arbitrariness: the arbitrariness that not everyone can consistently want. The anti-arbitrariness principle in ethics states that all unwanted arbitrariness should be avoided. If one thing goes for X, then it must also apply to all Y and Z that are equal to X (in the sense of belonging to the same set as X) according to a rule, unless everyone can consistently want that it just applies for X. Arbitrariness is only allowed if it is not against anyone’s will.
So if we avoid unwanted arbitrariness, we end up with moral rules that apply to everyone and everything, without arbitrary exceptions. More specifically we can formulate a fundamental ethical formula, such as: everyone must follow those moral rules of which everyone can want that everyone follows them, in all possible situations. You are not allowed to arbitrarily do whatever you want. So for everything you do, you have to be able to give a moral rule that justifies your act, and you must be able to consistently want that everyone follows that rule. If you cannot give such a rule, your act is not allowed. Or simply put: if you are allowed to do something, then so is everyone, because you are not special. You should not arbitrarily pick yourself from the set of all individuals and say that you are the only one who may do that thing.
This basic idea has far reaching consequences. It implies the golden rule: “Treat others as you would like to be treated and do not treat them as you would not like to be treated.” So we can easily derive things that you are not allowed to do, because you do not want them to be done to you. If you may forbid something because you find it unclean, unholy or disgusting, then someone else may forbid something that you like and s/he finds unholy or disgusting. If you may use vague or arbitrary reasons to justify your behavior that I don’t like, I am allowed to use vague reasons as well to justify my behavior that you don’t like. If you may say that we should follow your preferred holy book (such as the Bible or the Koran), I may say that we should follow my preferred holy book. If you may say that your moral intuitions are better than mine, I may say that mine are better than yours. If you may arbitrarily choose your victims, I may arbitrarily choose my victims. If you may say that your moral rules only apply to your preferred group, I may also take my preferred group of individuals, which may be different from your group. You cannot consistently want those things, so you may not do those things.
If you may follow your ethical rules, are racists allowed to follow their racist ethics? Are pedophiles, rapists and religious fundamentalists allowed to follow their ethics? You cannot want that. But the ethical systems of racists, pedophiles, rapists and religious fundamentalists contain inconsistencies, unwanted arbitrariness, unscientific beliefs and vague principle. So if your ethical system is more coherent than others (i.e. if your ethical system does not contain any inconsistencies, ambiguities and unwanted arbitrariness), then you can say that your ethical system is better than those of others and then you may oppose those incoherent systems of others.
Why should we avoid unwanted arbitrariness? Why is it bad to construct and follow incoherent ethical systems that contain inconsistencies or unwanted arbitrariness? Suppose that your ethical principles contain unwanted arbitrariness. If you say that that arbitrariness is permissible, then I may also follow arbitrary principles that you cannot consistently want. If you follow an arbitrary or inconsistent ethical system, I am allowed to reject that system and impose my coherent ethical system on you, because you are not able to complain. You are not able to give justified arguments against the imposition of my ethical principles, because by following your incoherent principles, you are acknowledging that inconsistencies and unwanted arbitrariness is allowed. If you don’t want me to impose my moral views on you but if you say that you are allowed to have inconsistencies, i.e. to have two opposing views at once, then I may hold the inconsistent opinion that I may and may not impose my principles on you. Even if these two beliefs are mutually contradictory, you cannot argue against it. If your moral rules contain unwanted arbitrariness, then you acknowledge that arbitrariness is permissible. That means that it is also permissible to arbitrarily ignore someone else’s moral views and ethical systems. So I can say to you that your moral values and judgments are not valid. And if you complain and says that your ethics is valid, then I can reply that if you are allowed to arbitrarily exclude other moral views and make an ad hoc exception for your own ethical system, then so am I. So I may even make the exception that everyone’s moral views should be respected, except yours. All your objections can easily be bounced back by saying: “If you are allowed to arbitrarily do that, then so am I. What would make you so special that you are allowed to arbitrarily exclude others but I am not?”
To conclude: we can arbitrarily reject someone’s incoherent ethical system, because that person acknowledges that arbitrary exclusions or rejections are permissible by acknowledging that arbitrariness is permissible. After all, that person uses an arbitrary system. That person can only give a valid complaint or argument if s/he accepts the anti-arbitrariness principle. Without that principle, any critique becomes invalid and complaints become impossible.
Tolerance and democracy
If I am allowed to construct a rational, coherent ethical system that best fits my moral intuitions and values, then so are you. Those coherent ethical systems should not contain inconsistencies, vagueness or unwanted arbitrariness. Everyone can construct their own coherent ethical systems. But there are many possible coherent ethical systems, such as a deontological rights ethic, a consequentialist utilitarian welfare ethic, a libertarian ethic or pluralist ethics that combine several ethical principles. We do not have a rule that determines which of those coherent ethical systems is the best. So picking one of those systems always involves unavoidable arbitrariness.
We cannot simply reject someone’s coherent ethical system, even if that system is different from ours. If we are against unwanted arbitrariness, we have to recognize that every equally coherent ethical system is equally valid. Everyone is allowed to construct his or her own ethical system using his or her own moral intuitions and values, as long as that system is coherent, i.e. does not contain contradictions or unwanted arbitrariness. I cannot say that my coherent ethical system and my moral intuitions are better than yours if both our systems are equally coherent. I prefer my system, but I cannot impose my system onto you, because what would make me so special that I would be allowed to do that? And the same goes for you and everyone else. It would be an unwanted kind of arbitrariness if we claim that our own system is special without good reason.
A rational ethicist is tolerant towards all other coherent ethical systems, no matter how much they go against one’s own moral intuitions. We are allowed to reject anyone’s incoherent ethical systems. This allows us to avoid an extreme form of moral relativism that says that all ethical systems, including incoherent ones, are equally valid. This extreme relativism implies that everything would be permissible, and we cannot want that. The claim that coherent ethical systems are equally valid is a kind of weak moral relativism, which is a consequence of the anti-arbitrariness principle.
How do we deal with that plentitude of coherent ethical systems that are equally valid? A special kind of democracy is the solution. Everyone (every rational ethicist) constructs their own coherent ethical system, and we can aim for a consensus or democratic compromise between everyone’s system by using a democratic procedure. In a democracy, everyone has one vote, or everyone’s vote is equally important, because we cannot say that one vote (one coherent ethical system) is better than someone else’s. A non-democratic dictatorship of one coherent ethical system violates the anti-arbitrariness principle, because there is no rule to pick this ethical system out of the set of all coherent ethical systems.
Note that the coherence of ethical systems imposes very strong constraints on the construction of ethical systems. We can expect that the resulting ethical systems that people construct, if they follow the anti-arbitrariness principle carefully, are not extremely divergent from each other. This strong selection and convergence of ethical systems makes a democracy of ethical systems feasible.
So there are two reasons why our ethical system should not contain unwanted arbitrariness. First, if it contains such arbitrariness, someone else is allowed to arbitrarily reject our system and we are not able to complain. Second, the avoidance of unwanted arbitrariness puts strong constraints on the possible ethical systems, which makes a democratic consensus between the resulting coherent ethical systems more feasible.