Taking together basic ethics and property rights from first principles, it is possible to define universal ethics. It is, unfortunately, very delicate, meaning (even more than usual) that you need advanced philosophical skills to avoid abusing the idea. In the end, these ethics justify multiple kinds of (what is normally) violence as self-defence. However, I've not found a succinct wording of the rule (there's only one.)
Because it is wrong to violate your control of your property, the only events which are morally valid for your property are the ones you value. Therefore, a particular inversion of the Golden Rule is true, a rule I once saw labelled the platinum rule. This isn't quite it:
Do unto others as they would have you do unto them.
A priori I would expect it would be wrong of them to demand donations of you, even though it follows a naive reading of the rule. Why is the demand, in fact, wrong? The angle I like best here is the angle that this value of theirs (hey, I like cash, and you have cash...) overlaps your own values for your own stuff, and becomes a self-contradiction by requiring that their values can change your values, which would naturally mean, by symmetry, that your values can change their values, but then their values can change yours which can change mine which...is just a mess, not logic.
Also, if you were morally constrained to follow this first approximation, it would be morally impossible to interact with anyone; practically speaking you cannot fully suss out someone's values before trying to have a conversation, and as such have to make assumptions about what they want. Even before this, looking at the logic, what if someone doesn't want to be spoken to at all? How can you find this out?
So. It turns out the libertarians are correct. Only negative rights exist, because all positive rights require that one person's values are allowed to set another's.
Do not unto others as they would have you not do unto them.
(This is still not exact.) As a first approximation, do not unto others as you would have them not do unto you. Until they inform you otherwise (ignorance is a defence) you can assume that humans are far more similar than different.
I said it was delicate. There's more, too; what about when someone doesn't want to be looked at, yet insists on walking down city streets? I don't want to get into value hierarchies right now, so the short answer is that first, ignorance is a defence, and second that this individual can't have both, and must value being outside more than being unviewed.
The idea is that you have your self, and your other possessions, and they should be treated according to your values, insofar as they can be so treated without automatically infringing upon the values of others.
Since it isn't useful to the general public anyway, perhaps I should stop trying to construct a soundbite version.
What is moral is to not intentionally contravene the values of others for themselves or their possessions, nor through neglect allow your actions to unintentionally contravene these values, noting that values that interfere, constrain, or are about the values of others are automatically invalid as moral values.
Also nice would be a single word that means 'moral values' to differentiate from the lay usage. Just use your spiffy hominid context-sensor for now. Values can still be values even if they don't work as moral precepts, even though I don't talk about that kind specifically.
In practise this works out nicely, in that usually people's values are other-neutral. In the donation example, there are many ways to become rich without extortion. In the second example, most likely the person who wants to be invisible doesn't want invisibility per se but rather has crippling low self esteem or is, in fact, ugly, both problems which are patched by invisibility, or by solitude, but could also be solved in other ways. These are means which illustrate a value, an end; the actual ends people hold are usually other-neutral. There's also marriage and similar, which is other-neutral to most individuals and looks for a matching other-non-neutral individual.
And, of course, most other-non-neutral values aren't valid, as they automatically lead to conflict between two individuals which can, in general, only be solved by violating one of the values - violence. Even if it is wanting the best for your kids, it's still violence to impose it on them. Your children are not your property.
Though this brings up another sticky, delicate issue, in that children must be a special case. The whole ethical framework depends on symmetry, and symmetry only provisionally applies to children, especially small children. For now, as I have no children of my own, I must leave the question unanswered, except to say that treating small children differently than adults is justified exactly to the extent that they are, in fact, scientifically, different than adults. Similarly, the difference in treatment must parallel the actual difference in properties and abilities. I don't think this will be much of a problem either, simply because children like being taken care of, with the addition that children can be convinced of just about anything by a parent, meaning parents can simply alter their values as needed.
But that's enough about what's right, I'm going to delve into what's wrong, specifically what it means in this framework if you violate someone's values. As far as I know, this is the only framework that automatically justifies self-defence, and needs no specific exception.
To violate someone else's values is to state that you don't value respecting other's values. By symmetry, you are, to them, an 'other' and as a result it cannot be immoral for them to violate your values - any of them. Again, there is some delicacy; using the logic thus far, you can happily murder someone for spitting on your shoe. I believe this can be fixed by appealing to further values, (you recoil from the idea of doing so; obviously following your own values would stop this kind of pathology) but until someone takes this idea seriously, I have no desire to fix it for them.
And here we come to something that gives me confidence in the framework's integrity; it has a place and purpose for forgiveness. To wrong someone is to lose your only right, but to gain their forgiveness, either through mercy or through reparations, is to regain that right. How would you like that, eh? In addition to 'how do you plead' at the beginning, every court would have 'and does the defendant grant their forgiveness for the sentence imposed?' If not, the defendent is welcome to offer additional reparations.
Section elided; how the framework interfaces very nicely with a justice system. Just know that from a bird's-eye view, our justice system can work perfectly in this framework, although the frog's eye view reveals that nearly every law is unjust.
To the politically sensitive: hello! This definition is the ultimate in pluralism. Because the only way to define ethics is from your values, what is ethical for you derives entirely from what you value, not from what other people value, regardless of all the usual considerations used to impose morality.
However, using this theory as a tool, I can now look at multiculturalism as well, and highlight one of flaws. Values differ somewhat between individuals, but the gradient shoots up between cultures. Without an agreement specifying how to translate actions across the interface, I can see from experience that, for instance, every Muslim expects multicultural infidels to act Muslim, while simultaneously their opposite expects the Muslim to act Anglo-Saxon. Using this framework as perspective, I can see that these ideas are not just rude, but highly evil.
Of course, with such agreements, a multicultural city can, theoretically, work like an oiled machine. If both value sets are intrinsically valid, the transformation between them should be possible or even trivial to figure out.
So I want to gain something practical from my morality. I actually started studying morality at a very young age, and I started with a single rule; pain is bad. Eventually I had to add too much, by my standards, onto this system to cover everything that seemed wrong, so I discarded it, but it was still a helpful stepping stone. What I wanted out of it I have, now, gained. If you complain when you feel wronged, the other party will, invariably, try to argue their way out of it. However, I now have an ironclad objective theory of ethics, which means that I can prove it, one way or the other, every time, instead of having to weigh one feeling against how I felt about doing something about it, which could be useful if I wanted to disentangle all my emotions in each individual situation.
This is especially important to me as I've found it is quite easy to simply impose my ideas upon the other person (unless they're in a government beaurocracy.) I know, from how it feels to contemplate this course of action, that I cannot rationally stop myself abusing this power without some objective technique.