One of the best resources you can find online is the Stanford Encyclopedia of Philosophy. Read their articles on

morality at https://plato.stanford.edu/entries/morality-definition/

deontological ethics at https://plato.stanford.edu/entries/ethics-deontological/

virtue ethics at https://plato.stanford.edu/entries/ethics-virtue/

feminist ethics at https://plato.stanford.edu/entries/feminism-ethics/

The encyclopedia has dozens of articles on ethics by expert authors.

Thank you, I appreciate, that is precise answer and I should definitely read these.

I also reformulated the question to emphasize that I am looking for a rule of thumb.

Dear Michal.

You ask for the best method to approximate morality of a public decision and rightly say that there is no complete definition of morality. So, to approximate morality of a public decision is a polemic issue.

Let me say that a comprehensive answer to your question would imply to write a book's chapter, an entire book or even several books, and hence,´it is beyond the scope of my answer. Accordingly, what follows is a short answer to your challenging question.

To substantiate that the issue you raise is a polemic issue, I decided to perform a brief digression about the most important theories of morality.

According to L. Kohlberg's theory of an ethic of justice, whose main injunction is that we should not treat others unfairly, a moral action or public decision is the one that passes, say, the test of reversibility ("Would we advocate the same decision if positions in the public decision at hand were reversed?"), and the universalizability test ("Did we reach a decision that would be acceptable for all at all times and places?"). Note that for Kohlberg justice is the basic moral principle.

According to I. Kant, a moral action or public decision is the one that accords with his categorical imperative, that is, we should act or decide as if our action or decision could be universalized or followed by all people at all places at times. As seems obvious, Kohlberg's tests of reversibility and universalizability are but different formulations of Kant's categorical imperative.

According to J. Habermas, a moral action or public decision is the one that would pass, say, his better argument test, that is, the argument based on rational, not instrumental, communicative action and discourse. Again, Habermas' idea of the better argument echoes Kant's categorical imperative.

According to J. Rawls' theory of justice, a moral action or public decision is moral and just when it takes into account his idea of veil of ignorance or original position. In other words, a public decision is likely to be moral and just when it ignores who is who in the situation of competing claims at hand, Again, Rawls' idea of veil of ignorance and original position is a different way of formulating Kant's categorical imperative.

The above mentioned authors all espouse deontological and procedural moralities. According to these moralities there are some actions that are moral in themselves (e.g., to steal to save a human life).

In contradistinction, teleological and consequentialist moralities, as those adopted, for example, by J. Bentham and S. Mill, advocate the principle of social utility, not the principle of justice. Thus, a moral action or public decision is the one that brings about the greatest good for the greatest number of people. Here a question arises: Who decide what is the greatest good or happiness to the greatest number of people?

According to C. Gilligan's ethic of caring and responsibility, whose main injunction is that we should not turn away from someone in need, an moral action or public decision is moral when it accords with the principle of benevolence. In other words, in a situation of competing claims, we should act and decide such that no one is hurt in psychological terms. As Kohlberg argued, benevolence cannot solve conflicts of welfare.

According to Aristotle and contemporary virtue ethics theorists (e.g., Marta Nussbaum), a moral action and decision is the one that is consonant with the principle of eudaimonia. In others words, the more an action or public decision leads to the self-actualization or self-fulfillment  of the focal people, the more it is likely to be moral and just.  Self-actualization is to be seen in terms of A. Maslow's pyramid of one's needs.

From the preceding considerations it is clearly visible that there are several and different ways of approximating morality of a public decision. In your question you speak about of a rule of thumb to be followed in a moral public decisions. As I see it, that rule of thumb could be the golden rule, whose general formulation is the following; Don't do unto others what you don't want others to do unto you.

I hope I have got your question and that this helps.

Best regards.

You ask what is the "best method to approximate morality of a public decision"? The phrase is vague as it stands. The best method to ensure that a public decision is moral is to have open debates on the issue under consideration. 

Thank you for your answers, I am sorry for being vague, I did not want to make the question too specific. I just wanted to see what ways of thinking are possible.

Let's do a little thought experiment. Imagine a person that knows all morality. In that case my problem is solved and will ask her what was moral.

But why such a person does not exist? Lack of information. What important information does she lack? 1.values 2. cuases and consequences 3.ethics, metaethics 4.will to be moral  ... 

So, if I would like to approximate I will need to heal the lack of information as much as possible.

1.Values. If values influence morality, we do have to ask those who hold the values. We cannot extract the values from them, they are often unable to describe them with sufficient precision.

2. Causes and consequences. Later evaluation helps a lot, education may be necessary in same cases.

3. Ethics, metaethics. As I see it the most often problem is scope. Is quite easy to forget to consider future generations, other nations, animals.

4. Will to be moral. Psychopaths and authoritarians are not particularly representative when it comes to morality. Still I do not know if I should see it as a kind morality.

Any more ideas that should be considered?

Is this a sensible though experiment? Is there any similar experiment?

First, you have assumed that "such a person does not exist", i.e., a person who possesses sound moral judgment. But this is a postmodern idea. Although Plato, for instance, could not define "the good", he never doubted the existence of people who possess good judgment in matters of morality. Kant thought that such a capacity was common. 

So, second, it seems to me that you are struggling with the problem of how to obtain moral knowledge in light of the fact that that there are many views (or perspectives) on any given issue. My own answer to this problem is to have sustained public debate (while keeping coercive influences at bay). In other words, the differing parties must remain at the table so that an intersubjective rationality might emerge to constrain decision making. (That is the short version of my response).  

Test for motive and consequence

Rule out purely selfish motives and selfish interests

Grant it prima facie ok status.

Dear Michal.

As the previous answers show, morality can be seen from different perspectives. Which one is right, and which one is wrong? In your thought experiment you refer to a putative person that knows all morality. What does this means? Does this means to know all that was written about morality and ethic? In principle, no one met, meets, or will meet this possibility. Keep in mind that morality belongs, say, to the "ought" domain or the domain of how things should be, not the "is" domain or the domain of how things are. So, the "ought" domain is an ideal domain. As such, no one can know all morality. By their very nature, an ideal may change according to time and place.

Let me address your questions:

(1) Values and morality. You say that if values influence morality...". Values do not influence morality, for morality has to do with moral values. Again, moral values differ in terms of time and space. As Michael says, the differing parties must remain at the table so that an intersubjective rationality might emerge to constrain decision making. This reminds me of Habermas' better argument and allows us to go beyond an untenable relativism (see more below).

(2) Causes and consequences. It is not clear to see what you are thinking of. As such I remain silent about this issue. As Wittgenstein once remarked what we cannot say, we must pass over in silence.

(3) Ethics, metaethics. As I see it, any moral/ethical theory is also a metaethical theory because it posits some assumptions that cannot be tested in empirical terms. Science could not tell us, for example, if the principle of justice advocated by Kohlberg is a better principle than the principle of benevolence advocated by Gilligan, or the other way around. What science can shows us is, for example, how people interpret the idea of justice, when confronted, for instance,with the following question: "Can you explain to me what is justice for you? Why is this so?"

(4) Will to be moral. Of course, the will to be moral varies, for example, as a function of individual's age, motivations, religious orientation, personality, and so forth.

All that said, it seems that as for as moral issues are concerned, we are doomed to espousing a constructionist stance according to which all knowledge and value is socially constructed and, hence, inherently relative. Contrary to this constructionist stance, constructivist perspectives, generally espoused by deontological moralities to which I refer in my previous answer, assume that individuals all construct the same understanding of knowledge and value as a result of their interactions with the physical and social worlds. Therefore, constructivist perspectives are at complete variance with the relativist assumption that lies at the heart of postmodernist approaches to knowledge and morality. Note that when one claims that all knowledge and values are relative, one is committed him/herself to what s/he says cannot be done. In other words, when postmodern and cultural relativists claim that all knowledge and values are inherently relative, they are displaying a non-relative claim, that is, they are, as it were, "absolutizing" the relative, which is a blatant contradiction in epistemological terms. Note also that the postmodernist relativist assumption embraced by contextual and narrative approaches (and authors, such as K. Gergen,M. Tappan, S. Benbabib) to morality leads also to nihilism because to claim that there are only local moral criteria justifies all alternatives and moral choices. That assumption leads also to opportunism because to propose only local and contextual criteria for defining what morality is about blurs the difference between justice and injustice, morality and immorality, and cooperative and instrumental interpersonal relationships,

All of this means that morality goes well beyond one's personal preferences, needs and desires and that an intersubjective rationality may emerge to constrain decision making when competing claims are at issue.

Best  regards.

Hi Orlando, 

Which theorists do you take to qualify as "constructivist"?

Hi Michael.

Among other theorists, Jean Piaget and Lawrence Kohlberg are widely accepted and constructivist, not constructionist, author. In my previous answer I refer to what is distinctive of a constructivist claim and a constructionist claim. These claims are at complete variance with each other.  

Hi Orlando,

I cannot see how either of Piaget or Kohlberg are going to be able to hold down any kind of non-relativistic morality. 

Thank you again. I see that a defense of any method is almost impossible, I just need to make my guess and hope somebody will do better more practical or precise later.

I created a new question

https://www.researchgate.net/post/What_is_your_best_guess_at_variable_approximating_goodness_of_public_decision_more_precisely_outputs_of_public-decision_making

Dear Michael,

I think that you find a response to your question in the following chapter by Kohlberg. L. (1971). From is to ought: How to commit the naturalistic fallacy and get away with it in the study of moral development. In T. Mischel (Ed.), Cognitive development and epistemology (pp.151-235). New York: Academic Press. As I see it, in this chapter, Kohlberg was able to hold down, say, a relativistic morality. After reading it, you will see that Kohlberg was able to hold down relativistic approaches to morality.

Best wishes,

Orlando

Given that there are a variety of normative moral theories, a justifiable decision-making progress avoids absolutizing any of them, whilst recognizing that any of them may address conditions to some extent. The process of reaching a justifiable judgement is thus one of accepting approximation, whilst self-consciously avoiding the absolute acceptance or rejection of any of the potential moral approaches. Which approaches we may be inclined to absolutise (whether positively or negatively) will depend on the context, and thus how we avoid them is also contextual. The contextual factors include exactly which person or persons is making the decision and which absolutized theories they might otherwise be likely to fall into.