Last Name Debate

Question... If you happen to get knocked up and you are not with the father anymore, should the baby still get daddy's last name? I had this discussion last night with my friend. I have a boy and his father and I (although we were together when he as born) were not married. it was always my feeling that my baby would have my last name since I wasn't married. I told him that when we did get married I would change the boy's last name along with mine. For some reason it was important for me to share the same name as my child. However, my friend says that a child should always get the father's last name regardless b/c its tradition and b/c its "his child too" and they could lose that piece of their identity. Yes it is a tradition... because traditionally people were married when they brought children into the world so everyone had the man's last name. But given the nontraditional birthings of late is this still the standard. I personally think that if the two people are not married at the time of birth then the child should have the mother's last name unless she wants to give the child the dad's name. Its not a thing of spite or ill will, just logistics. And though it is nothing to brag about, I have a number of women in my extended family that have experienced single-motherhood and they each gave the baby their name with the exception of a few that actually had pending marriages. So I think that's completely normal. But I could be very wrong in my thinking. What do you think? and why?