Have been thinking a lot recently about the range of "theories" that have been current at one time or another in the history of philosophical inquiry into moral claims and of human claims about behavioral goodness in general. While it's hard to capture everything, I have compiled what seems to me a fairly exhaustive list of different moral "theories" which include some twenty possibilities. Of course I'm sure this isn't exhaustive and there are probably many nuances I have not adequately captured. Moreover, there are some strong similarities among some of the categories which suggests room for disagreement about which qualifies as which. I've tried in what follows to sort them as cleanly as I can and to identify a few of the main thinkers associated with each (where there are such associations to be made)
In the final analysis, I think it can be helpful to look at the range of possibilities and see what fits where and who and what may have been left out:
The Scope of Moral Accounts
• Naturalistic Accounts (What we call ethically or morally "good" is some feature or phenomenon of the natural world.)
Ancient
The Greeks broke ground by offering a variety of explanations which sought to go beyond the priestly and social admonitions of their particular culture, including that which we mean by our uses of the word “good.” The good, they proposed, was variously:
1) Whatever counts as the fullest exercise of man’s unique capabilities, his behavioral dispositions (such as rational inquiry, the capacity to think and challenge ideas), what is unique to human beings (Socrates).
2) The qualities in humans most in keeping with harmonious relations with others in one’s community so that the community (the state or polity) shall be in balance (Plato).
3) The qualities in humans which we are naturally given to admire as proper to the best humans and which are exemplified in virtuous persons because they are most suitable for a human to possess in order for that human to be maximally content, i.e., to flourish as a human (Aristotle).
4) The qualities most suited to bringing about a contented life for humans, such as the sort envisioned by the Epicureans and Stoics.
Modern
Naturalism – In modern times we have seen a resurgence in the effort (first seen among the ancient Greeks) to explain the notion of moral goodness as a function of the natural conditions which are thought best suited to human thriving. Thinkers like Anscombe, Foot and Baier have proposed various ways in which what we think of as morally good or right can be explained in terms of behavioral inclinations we call justice, honesty, aversion to theft, and so forth, because these behavioral types are thought to be built into the kinds of creatures we are (i.e., we are social, thinking creatures whose “forms of life” – the institutions and practices which make up our lives – are characterized by the need for these types of behaviors).
• Religious/SpiritualAccounts (What we call ethically or morally "good" is determined by higher order, e.g., divine, fiat.)
Authoritarian:
Ancient
What is good is what the gods decree (Hammurabi, Mosaic code, pagan belief systems, etc.)
Medieval
What is good is obedience to God’s will (lovingly submitting to God in the Christian ethos) through self-abnegation (subordinating one’s own needs and desires to those of others) or submission, by subordination of one's will to God's, in accord with what's needed to advance God's plan on earth (the Muslim ethos) or maintaining loyalty to God, as a sovereign, by keeping his commandments (Jewish ethos).
Intrinsic/Mystical/Experiential (Irrational or Non-Rational):
Ancient
Hindu/Buddhist - What is good is that which liberates us from the ties that bind us to an illusory existence including behaviors consistent with or conducive to attaining such liberation.
Modern
Tractarian Wittgenstein – What is good (in the moral sense) is "transcendental" and so inexpressible; it is nothing more than the "sublimity" we feel if we approach life in the right way and then the things we do, arising from such experiences, will be consistent with what we think of as morally good.
• Rational Accounts (What we call ethically or morally "good" is determined and justified by reasoned reflection)
Ancient
Confucianism, Taoism (and, of course, there is an important reasoning component in the ancient Greeks, too, especially in the Socratic position) - What is good is that which promotes and sustains harmony in the universe or in society (this particular formulation also resonates with Plato in ancient Greece)
Enlightenment and Post-Enlightenment
Kantian – What is good is to follow the dictates of reason, which oblige us to do our duties to other rational beings like ourselves (duties which also just happen to basically reflect the classic Christian duties) because reason requires a rational will.
Utilitarianism – What is good is whatever produces the greatest happiness or pleasure for the greatest number (Bentham, Mill, Smart, Williams) This account breaks out into two main versions, act utilitarianism and rule utilitarianism. The first looks to the utility of individual acts while the second to the utility of general rules or principles against which individual acts may be measured. (Another distinction differentiates between the "goods" aimed at, e.g., between happiness, which is construable in a more abstract way and so suggests more sophisticated possibilities, and pleasure, which suggests a more basic phenomenon, suggestive of less laudable objectives.)
Contractualism - What is good (in the moral sense) is whatever is supportive of the implicit contract(s) into which we enter with other human beings in order to live together effectively in social groups (Hobbes, Locke, Rousseau, sometimes Kant). Humans are thought to be inclined toward, and so capable of, entering into such arrangements, which arrangements require particular behavioral practices like honesty, loyalty, law abidingness, etc. (One version -- T. M. Scanlon's -- argues for standards based on what reasonable people can be expected to grant if the standards were applied to themselves.)
• Non-Religious/Non-Rational Accounts (What we call ethically or morally "good" is built into our human nature/capabilities and is not dependent on reasoning to justify it.)
Modern
Intutitionism – What is good (or right) is knowable directly, as we know our most basic perceptions, and not amenable to further description or reduction to anything more basic than itself (Moore, Sidgwick). We know the good when we see it!
Linguistic (the later Wittgenstein) – What we mean by "good" depends on the different uses we make of the word and other words like it.
• Skeptical/Rejectionist Accounts (What we call ethically or morally "good" is non-factual and therefore non-justifiable.)
Enlightenment
Humean – What we call “good” is what we feel affinity for albeit without any supportable basis that can be rationally argued for.
Modern
Emotivism –What is good is not an intelligible statement but only the expression of our sentiments about things (see logical postivists like the early Ayer)
Subjectivism – What is good is whatever we like, prefer, etc. (Paul Edwards)
Prescriptivism – What is good is nothing whatever since, to call something “good” is really just to urge someone to do or obtain it, i.e., it’s to prescribe it as a course of action. (R. M. Hare)
Sentimentalism - what is good (or not good) is whatever a community of moral practitioners accepts as consistent with the majority of the members' affinities (and disaffinities) (Jesse Prinz)
My own view can, perhaps, best be characterized as Value Functionalism (at least for now). It proceeds in two major steps (taking its name from the way in which the activity of valuing is conceived, i.e., as an indispensable function of reasoning). It argues that:
1) What is good, in general terms, is whatever can be seen to have features which provide an agent a reason to choose the entity/practice/objective in question which has those features; and
2) What is morally good are whatever actions express intentions consistent with the agent's maximal realization of its own subjectivity (thereby providing the agent a reason to choose to perform those actions over others which aren't consistent with that realization).
This latter, moral, dimension of valuing stands on the notion that humans, as subjective entities (with a mental life) can only fully realize their own subjectness (that mental life) by granting subjectness to others whose behaviors also evidence a mental life, i.e., subjectivity implies the capacity for reciprocity with other subjects and fully realizing one's subjectivity is dependent on exercising that capacity.
This account has affinities with the others in different ways but does not entirely fall under any of the other categories.
1) It fits with the naturalistic notion that what is thought good is always something that is part of the natural world and moral goodness is the goodness of certain actions which are entirely rooted in the natural world. In this case, though, it is not human-specificity that matters since it’s not human qualities per se that are at issue but those associated with being subjective which are, in principle, possible for other (non-human) kinds of entities as well, i.e., the basis of ascriptions of moral goodness is the presence or absence in the agent of the condition which expresses subject-to-subject recognition: empathy.
2) My approach also aligns with intuitionism because, like that account, it holds that we recognize the good when we encounter it directly, without need of argument or explanation (to the extent that we are in the right state). While we may reason about the presence or absence of goodness-making features or about the implications for our further actions, we do not need to reason out what is morally good. We only have to know whether the behavior is empathetic in an appropriate way or not.
3) The approach does, however, stand on a rational basis because it is grounded in an account of how reasoning works in creatures like ourselves, i.e., valuing (including instances of moral valuing) is seen as a necessary and integral element of our reasoning mechanism.
4) It fits, as well, with Humean skepticism in that it regards all instances of valuing as expressions of human feelings (wants, needs, desires, affinities).
5) Finally it has a religious/spiritual aspect in that it rests judgments of moral value on personal realization rather than logical compulsion via reasoning, that is, on having a certain kind of experience of the other – and of recognizing the value of having it.
Importantly it hinges on a decision to treat mental referents as referrable in a roughly analogous manner with physical referents.