What could be considered a good foundation, for a theory of ethics?

Question:

What could be considered a good foundation, for a theory of ethics?

I think Aristotelian ethics are the best foundation I know of. However I'm asking about a scientific or philosophical way of determining sound ethical principles.

Best Answer - Chosen by Asker: Depends.
A logical ethical system must begin with a premise and work to support that premise.
Pick your core belief ... a judgemental supreme being, or karma, or enlightened self-interest, or self-actualization, or whatever ... and establish your ethics towards that belief.
Thus, an ethical response to someone kicking you in the shins would vary considerably, depending on your core premise: retaliate in kind, sympathize, run away, or kill, or what have you.
This is not a simple process, naturally, and what seems to me to be a good foundation may not work for you.
Suppose (being self-centered) I were to tell you that a good foundation for your theory of personal ethics would be "Help Grendle Achieve Wealth"? Would you think that this was a worthy goal upon which to found your ethical theory? I think not.
Similarly, if someone tells you, "Come thou and devote your life and all your wealth and effort to my belief system", you should take a moment to consider if this is really in keeping with your core premise.
So to determine that good foundation, first, find that chewy nougat center to your beliefs, whether it is a deity, or a sociological conviction, or a scientific premise or whatever. Then go from there.
I know this isn't a hard and fast answer, but any such answer should be suspect.