Ethics comes from the greek word "ethos" which means character. The character of the self. This goes all the way back to Aristotle, who basically stated that ethics is the behavior of the individual.
To judge whether that behavior is ethical or unethical, you must have a standard against which to judge that behavior. The relative nature, or perception of ethicalness, comes in by choosing which standard by which you're going to judge that behavior. An single act can be both ethical and unethical by judging that act against two different standards. Society as a whole has a standard, which is the morality of the socity. But within the society, sub-groups can define their own rules, their own "Code of Ethics", which does not have to agree with each other, or with that of the larger society. And of course, as individuals, we have our own codes which guide our behavior. This is usually referred to as a conscience. But in all cases, ethical judgement is a relationship between the self, and standard by which that behavior is being judged. Everyone contributing is correct is some measure because we're not all using the same standards to judge whether the behavior is ethical. Now as to determine which standard is correct, for starters, lets consider that old phrase, "your right to swing your fist stops where my nose starts"
I can understand that my example (using the verb steal) of self directed behavior as a guide for imposed behavior as being a poor choice and misleading. Perhaps a better example would have been: If I slap myself in the face because I made a mistake, should in no way be construted as permission for you to slap me if I make a mistake. I feel it would be a terrible mistake to judge how you treat another based on how they treat themselves. By extension, people will give friends latitude in acceptable behavior that they would not grant to strangers or fellow office workers. The family also can operate under a different standard. You could easily get into a heap of trouble if you tried to justify your behavior towards someone else just become that person allowed that behavior from a third party. So I reiterate that your basis of behavior should based on what you'd like others to do to you, and not what you perceive others doing (or even allowing) to themselves.
To put into ethical terms, what you perceive another person's ethical standard of self directed behavior to be, is not an acceptable standard on which to judge your ethical behavior towards that person.
Or perhaps the question could be phrased differently. If Person A commits an act against Person B, whose "Code of Ethics" should take precedence in judging the act to be ethical - Person A or Person B?
Good Luck
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As a circle of light increases so does the circumference of darkness around it. - Albert Einstein