So here is my basic issue: You've taken an oath to do something, but now that means you have the choice of breaking your oath or doing something that you personally disagree with. What do you do?
For me, breaking an oath is a big deal. In my book people of integrity ought to do what they say they're going to do. Now obviously there is a bit of a scale to these things; a formal oath is a bit more important than your average idle promise. An oath or a vow is a formal way of saying 'this is important and I really mean it'. Its how we differentiate an big important promise from just idling agreeing to do that third load of laundry. If a person takes an oath to do something, I expect them to do everything in their power not to break that oath. That is what oaths are for. Its why people go through the formality of swearing to tell the truth, the whole truth and nothing but the truth in court. Its supposed to mean something, something more than simply knowing that you can theoretically be prosecuted for purjury.
So why do we need oaths? Well, we need them because we need to be able to trust certain people in order for society to work. We need to trust that the police officer who has just pulled us over actually believes we were speeding and is not looking for a bribe. We need to believe that the judge deciding a case is actually ruling based on established law, not which lawyer handed in a bigger bribe. We need to believe that the doctor treating us is actually treating a condition that we have and not just making stuff up to collect insurance payments. If we can't trust these individuals in these situations then society starts looking very bad very quickly. So we ask these people to take oaths, trusting that giving their word will be enough for all but the truly bad apples among their number.
So then we get to the part that disturbed me, the part where a friend seemed to say that he thought it was better to violate his oath than his personal ethics. Perhaps that statement doesn't seem like a nonsequiter to everyone else, but personally I find it hard to imagine a personal code of ethics that does not have keeping one's solemn word right up there at the top. I can imagine it not being your absolute number one, but generally ethical people I know who have something higher on their lists don't tend to put themselves in situations where its even vaguely likely that they'd have to violate their solemn word. To put it more concretely, people who feel that killing other people is never justified don't tend to join the military. Perhaps I am old fashioned in this, but I take oaths to be very serious things, and if you would violate your most solemnly given word, how am I to trust you in anything? Put another way, if there are a great many things that are potentially more important to you than your given oath, isn't that just another way of saying you are a flake?