These days anything that anybody thinks we need or want is called a right to it. Rights language is overused to the point it loses its power. I won't even try to list all the "rights" that have been claimed in recent years by somebody.
This is a complicated issue, and I do not claim to have mastered the subject either historically or philosophically. But at least the following distinctions might bring some clarity and precision to what in our national conversation is an unbounded surfeit of loose, if not anarchical, talk.
At least three categories come to mind: natural, constitutional, and legal.
Natural Rights are claims we have
by virtue of being human. This list would be short and include the fundamentals: life, equality, liberty, justice for all, and the pursuit of happiness. A natural right cannot be established or taken away by civil law. It can only be recognized and protected. We have rights that are "endowed by God" or nature.
Constitutional and legal rights arise by
virtue of being a member of a particular society. The former are grounded in the Constitution as determined by the Supreme Court. The latter are legislative enactments not in conflict with the Constitution.
The order of argument be be as follows:
1. There is a need or desire for which legal provision and protection should be given for the good of individuals and society.
2. The need or desire is either Constitutionally required or permitted.
3. If not Constitutionally required or permitted, it should be because it is rooted in something fundamental in our human nature and essential for our fulfillment as individuals and as a community.
Conversation should begin at 1 and proceed to 2 and 3 only when necessary. For example, adequate health care for all can initially argued for on 1. Hence, instead of speaking of a right to health care, it would be better to say that we have a need for health care and a just claim on available resources that should be given legal status for the good of society. The kinds of health care that should be provided have to be negotiated in terms of what a particular society can offer and is able to afford. Universal health care can be argued for on the basis of need, justice, and the good of individuals and society. If one wants to claim health care as a right, then it needs to stated whether this is a natural or constitutional right. Otherwise, it is loose talk that means no more than 1 anyway.
Marriage requires a different formulation. It does not involve costly resources and availability but is a matter of granting legality to certain forms of relationships along with certain formalizing rituals. It is permissible, thought not necessary, to claim that we have a right to form unions with a partner for purposes of reproduction, companionship, and mutual love based on our sexuality that is part of the nature we were born with. All three factors are equal, and reproduction is not a
sine qua non.
Moreover, marriage in the primary sense refers to a certain nature and quality of relationship between the partners. Legality is a socially useful way of recognizing and protecting the relationship. This was the basis on which I declared my son and his partner married regardless of what the laws of Ohio say. It would be sufficient to argue-- apart from any natural right--that we have a need and a desire to form such unions. Therefore, governments should recognize and protect such unions legally. (I have previously argued that arguments from nature and natural law are no more effective than any other, since no argument is persuasive for anybody except those who are persuadable by it. These days it is certainly not profitable to "hold these truths to be self-evident."
http://www.frontiernet.net/~kenc/law.htm)
The forms of marriage are a matter for each society to determine based on what works based on justice and the good of individuals and society. Gay marriage can be justified on this basis. Polygamy is different in that it violates justice, since if some men have more than one wife, other men and lesbians can have no wife. But if polygamy is permitted, then polyandry should also.
Should older men be able to marry more than one older woman, since they greatly outnumber men? I see no objection in principle, but would it work satisfactorily in our society and benefit the partners without doing harm to society? I don't know, in some cases it might, but if a ninety-eight-year-old man can marry a twenty-year-old woman, then polygamy for older people is worth debating. Since there is no outcry --or tolerance--for polygamy or polyandry, at the moment it is a debate about principles.
This gets complicated, of course, but it would be better to make an effort to sort it all out rather than to dilute rights language by such overuse and ungrounded rhetoric that it becomes practically meaningless.