Some time back there was a fellow in the news named Matt Dubay, a man who was claiming that Michigan's paternity law is unconstitutional because it didn't give him any 'choice' in whether to become a father.
The interesting thing about this suit is that it points out the inherent contradiction's in the current legal understanding of sex in the United States. On the one hand, a woman must be given a 'choice' as to whether or not to be pregnant after she has already conceived, and so abortion is legally mandated. On the other hand, a man is considered to have already made himself financially liable for any children conceived from the moment that he has sex. Thus, in the man's case, US law recognizes a traditional understanding of what sex is (an act that can naturally be assumed to be fertile) while in the woman's case sex is merely considered an act which may bring on a transitional condition in which a woman has conceived yet has not yet decided whether or not she wants to actually be pregnant.
Clearly, being pregnant (and caring for a child) is a far, far greater burden for a woman than for a man, so one can see how (thinking with its heart rather than its head) our country got itself into this position. But it's still a pretty untenable position to be in. Clearly, one must say either than sex is an act which has the inherent potential to create another human person, or it is not. One of these positions, of course, has the benefit of being true, while the other might be convenient for some, but is quite provably false.
However, while I do believe that the law should protect a newly conceived human being from her mother's second thoughts just as thoroughly as it does from her father's, it does seem to be that there is a hierarchy of claims to parenthood of the child in situations where a man and woman conceive outside of wedlock. Currently (at least from what female coworkers who have dealt with these situations tell me) if a man can prove that he is the father of your child, he has (unless this is somehow considered dangerous) both financial duties to you and visitation rights to the child.
This seems to me a little off. If a woman is willing to claim a certain man as the father of her child (and if there is any question about it, if tests prove her right) then it seems fair to me that he be both required to take some financial responsibility for the child and also allowed to have visitation rights or shared custody. However, if the couple have never been married and the woman wishes to refuse to acknowledge the man as the father of her child (even if biologically speaking he is) it seems to me to be reasonable to allow him to exclude him from the child's life, assuming she also does not try to seek money from him.
This may not be 'fair' in the sense that many use the term (as in, treating everyone equally regardless of whether that makes any sense) but it does seem to me to make a certain degree of sense.
Though on the devil's advocate side (or the libertarian side -- in this case they are one and the same) there is a certain sense in which allowing any demand for child support from a man to which one has never been married weakens the importance of marriage as an institution. If a woman need not be married to a man in order to be assured that she can hold him financially responsible for any offspring she may have with him, than being married before having sex is at least somewhat less urgent.
In the words of The Hitchhikers' Guide to the Galaxy: "To summarize the summary, people are a problem."