"I'm saying that I can see how moral quandries that present as individual problems are simply manifestations of the individual's attempt to work through arbitrary social norms."
[WS:] The manifestations of these norms may be arbitrary, but their existence is not. Ditto for the language - the rules of syntax or the meaning of words or symbols are arbitrary in the sense that they are determined by a particular culture and change from one culture to another. However the very fact that people do use language that is composed of syntactic rules that determine the structure of expressions and ultimately thoughts is hardly arbitrary - it is an essential part of human nature found in all societies and cultures.
The same can be said about ethical values. The very fact that they exist is universal, and thus not arbitrary. I would go even further and say that there are some norms that are universal. One example is the norm of reciprocity. AFAICT, all societies and cultures enshrine reciprocity i.e. equal exchange of values among human actors as a guiding ethical principle. Values assigned to different objects or actions as well conditions under which the norm or reciprocity may be applied or suspended may be arbitrary in the sense of being socially constructed but the existence of the reciprocity rule and the concept of value that this rule implies is not - since every human group in history seems to have it.
I would go even further by saying that the concepts of sanction, punishment and retribution are universal i.e. a part of the nature of human cognition, rather than arbitrary. All human groups seem to use sanctions, punishments and retribution for the transgressions of social norms - they seem to be a natural logical extension of the concepts of reciprocity and value. However, specific forms of these sanctions, punishments and retribution as well as conditions under which they are applied are "arbitrary" in the sense of being socially constructed and thus varying from society to society.
To sum it up: specific manifestations and applications of ethical norms are socially constructed i.e. "arbitrary," but the existence of such norms as wells as certain norms, such as reciprocity, sanction or retribution are not - they are an innate, universal elements of human cognition.
Wojtek