Yes, everybody kind of agrees on what are the right answers in common situations (like "murder of a human who does not present a threat to others is bad") but for every principle which aspires to be general its detractors have been able to present an example where it leads to conclusions which can not be universally accepted as ethical. For me that is strong evidence that there is no such principle.

An apt analogy with software engineering! I guess I believe that there are no universal principles there either. If the OO-evangelist and the lisper then each go on to develop useful and robust applications then they are both right (and that puts me squarely into consequentialist bucket with regards to software :)).