Are you boiling down Natural Law into one thing-the taking of innocent human life? I had a broader scope in mind which I think you do to.
But let's assume that Natural Law ONLY encompasses the taking of human life. Your pirate analogy ("You pirates don't kill us, we civilized folk won't kill you.") indeed sounds strange coming from the pirate's perspective ("You civilized folk don't kill us, we pirates won't kill you.") The cultural differences is apparent. How do you know the "civilized" folks are much more in tune to their Natural Law then the pirate folks? Just because you happen to agree with the civilized folks doesn't mean your Natural Law self isn't skewed as well.
My point is without some clear guidance, our moral compass is skewed. The Gnostic might have been right had not God given us His word. While Moses was up on Mount Sinai and God was writing the tablets, the children of Israel (Aaron included who should have known better) was making golden calves, breaking the laws even as God was writing them-Ex 32. They didn't exhibit any Natural Law so why would you think we are any better then they and have an innate sense of Natural Law? God could have just said, "follow your conscience".
I was wondering when that verse in Romans would turn up. Indeed those:
"Who shew the work of the law written in their hearts, their conscience bearing witness to them"
This isn't about a Natural Law that mankind can and should aspire to. The law Paul talks about does not justify, it condemns.
Rom 3:19-20 "Now we know that whatever the Law says, it speaks to those who are under the Law, so that every mouth may be closed and all the world may become accountable to God; because by the works of the Law no flesh will be justified in His sight; for through the Law comes the knowledge of sin. "
It is there to condemn-to show that no matter how hard we try we CANNOT live by it. I'm afraid I would have to post most of Romans but consider:
Rom 2:20-22 a corrector of the foolish, a teacher of the immature, having in the Law the embodiment of knowledge and of the truth, you, therefore, who teach another, do you not teach yourself? You who preach that one shall not steal, do you steal? You who say that one should not commit adultery, do you commit adultery? You who abhor idols, do you rob temples?
Rom 5:20 The Law came in so that the transgression would increase; but where sin increased, grace abounded all the more,"
The law God gave us in our hearts was not one in which mankind could aspire to. It was one in which revealed our sinful self. This is not a law we can live by. If there was Natural Law Paul would say "you who preach that one shall not steal, listen to your inner self."
Law is a term used about 200 times in the Bible, meaning a rule which regulates human conduct. Six subdivisions of the Bible doctrine of law follow:
1. NATURAL, INHERENT, OR INTRINSIC. That which God requires of every creature because of His own character, as it is written: “Be ye holy; for I am holy” (Lev. 11:44; 1 Pet. 1: 16). This law was binding upon all, from Adam to Moses (cf. Gen. 26:5; Rom. 2:14-15; 5: 12-14).
2. PRESCRIBED BY MAN
3. By MOSES
4. REVEALED WILL OF GOD IN ANY FORM
5. MESSIANIC RULE OF LIFE FOR THE KINGDOM
6. OF CHRIST
The prohibition of the taking of innocent life is but one example of a principle of natural law.
My point is without some clear guidance, our moral compass is skewed.
I take it you mean guidance clearer than human reasoning. I and most natural law theorists agree with this. Natural law is not a substitute for revelation, though with God's grace it can point the way to revelation. Both Budsizewski and another natural law theorist named Alisdair MacIntyre were lead to Christianity in part from their revulsion at the amoralism of Nietszche and Marxism, respectively. Their attempts at accounting for that revulsion led them to the Christian natural law tradition.
The cultural differences is apparent. How do you know the "civilized" folks are much more in tune to their Natural Law then the pirate folks? Just because you happen to agree with the civilized folks doesn't mean your Natural Law self isn't skewed as well.
Your skeptic pose is tiring me. Are you really willing to say that there is no rational basis for distinguishing between civilization and pirates? Are we really to be neutral between the fire brigade and the fire? If so, we'll have to say without qualification "One man's terrorist is another man's freedom fighter." And my "agreement with the civilized folks" is no mere happenstance, it's come out of a lot of contemplation and prayer. Pirates don't do much of either.
As for how I know if my natural law reasoning is skewed, God so deigned to give us a couple of error-checkers in addition to my individual human reason: the thought of other men wiser than I, and the church, and the bishop of Rome. Thought, like salvation, has communal as well as individual aspects.
The Gnostic might have been right had not God given us His word.
It's strange you should say that. I would say the Gnostic might have been right had God really been the wicked demiurge they believed him to be.
While Moses was up on Mount Sinai and God was writing the tablets, the children of Israel (Aaron included who should have known better) was making golden calves, breaking the laws even as God was writing them-Ex 32. They didn't exhibit any Natural Law so why would you think we are any better then they and have an innate sense of Natural Law? God could have just said, "follow your conscience".
Why are you so sure the Israelites didn't have an innate sense of the natural law? Their sinfulness doesn't require ignorance. A man may have knowledge of mathematical laws, yet break them through a lapse of the mind or maliciousness of heart. This is not to say that the moral law is knowledge at the level of mathematical certainty, but the analogy holds.
This isn't about a Natural Law that mankind can and should aspire to. The law Paul talks about does not justify, it condemns.
Natural law is not about salvation, it's about knowledge. And knowledge in itself doesn't save. It's enough for me that St. Paul speaks of a law known even to the gentiles. As for other possible references to the natural law in St. Paul, I myself suspect that St. Paul's line in Ephesians 5 "For who hates his own flesh?" is a rhetorical question acknowledging the self-evident goodness of the body of oneself and one's spouse and the communion of those two bodies--in other words to a sort of natural law principle which can be reasoned from.
If there was Natural Law Paul would say "you who preach that one shall not steal, listen to your inner self."
Look, you are attacking a straw man of your own construction. St. Paul taught that one's "inner self" was fallen and had to be formed by God working through His church, body mind and soul. That's just what Christian natural law theorists believe.