It's been two years now since I got a job and moved to a new city. I've grown more distant from my family and friends from home. Sometimes I wake up and my life bears absolutely no resemblance to what it once used to be. How can I be sure that I am still the same individual? What obligations do I have to the people with whom "I" once was close?

It sounds as though you are already making a break with your past (putting "I" in quotes suggests that you think of yourself as a different person, for when you describe yourself as you are now, you are not using quotes). You mention family and friends. Insofar as you have made vows of life-long partnership as a spouse and insofar as you have not renounced the duties of family life (one's obligations as a parent or child or sibling) it seems you do have some prima facie duty to "keep in touch" with that "I" or self whose life is bound up with theirs. This might involve not just increased visits, but more electronic and alternative means of communication so that they have more of an understanding of your current situation (send photographs of your appartment, favorite places in the new city, etc). Philosophers disagree about the extent to which friendships involve obligations of that sort. Some think of friendship as a gift, others may think of it as a gift as well but believe that once given and received, there are some duties that go along with it. These may be trivial (not breaking confidences) or substantial (going to their aid at considerable cost to yourself). However you stand on friendship and duty, I suspect that even calling someone your friend requires that you are actually interested in them (at best, you love them), such that if you are no longer interested in them, there may actually be no more friendship there. There may be one-way affection (they may love you) but without reciprocation, the friendship has ended. Ceterus paribus, I would urge you not to let these frienships end too easily. You have a good in older friendships (years of fidelity, love...) that is precious.

Read another response by Charles Taliaferro
Read another response about Identity