-Whether the Moral law is subjectively or objectively grounded
-Whether the grounding of the Moral law is a valid argument for the existence of God
Objection 1
It seems that Morality is not objectively grounded. For human beings are well capable of discernment of right from wrong without the help of religion. Further, since the knowledge of what is good from what is bad is known by all, and since even animals demonstrate some kind of empathetic feelings towards their own, therefore no religion or God is required to ground the basis of moral law.
Objection 2
It seems that the moral law argument is not a valid argument for the existence of God. For it can be demonstrated that no God needs to be invoked to account for the grounding of the moral law. Since men are well capable of discernment between right and wrong on their own without the help of God, religion or the bible.
Reply to objection 1
I answer that, if there is no God, then the difference between good or bad is simply a subjective opinion. That any mans idea of murder been a bad thing is no different from his preferential choice of tea over coffee. And just as he cannot impose his preferential choice of tea over coffee onto someone else who prefers coffee over tea, likewise he cannot impose his idea of murder being a bad thing on to someone else who holds a different opinion, why, because they, just like him are simply exercising their freedom of opinion , something which everyone is entitled to. Because at the end of the day all those different opinions are nothing more than preferential choices i.e. subjective opinions.
Further more, since opinions do change from time to time, it means that the idea of murder as a bad thing today might change tomorrow based on someone's change in opinion. And still that person would be truly entitled to their new opinion, just like your preferential choice of coffee over tea might change tomorrow and you would still be entitled to your change of opinion.
On the contrary, if all human related subjective opinions about murder were to change tomorrow, such that their idea of murder is that it is now a good thing, it would still remain as we know it, that murder is a bad thing. No one would stand around and watch as their family is slaughtered and thank the murderers now that murder is a good thing. And since it doesn't change, that goes to show that the idea of murder been a bad thing was never really grounded in subjective human opinions after all. And the same goes with empathy. If a man is not empathetic about murder, that doesn't mean murder is now a good thing. And that shows as well that the grounding had nothing to do with human empathetic feelings in the first place.
Reply to objection 2
I answer that, the grounding of the moral law is a good argument for the existence of God. For as demonstrated above, the grounding of what is right from what is wrong cannot be based on human opinions i.e. subjectivity. It therefore follows that the moral law has to be grounded in something else other than human related opinions. And that grounding cannot be lower than the opinion and nature of human beings. For rocks and animals and plants alike cannot form any kind of grounding for the moral law. But which mind and nature is higher than the mind and nature of human beings. And which mind and nature is this capable of not only distinguishing the good from the bad but also embedding that same distinction into the very fabric of reality itself. That mind and nature has to be the source of reality itself, an idea that leads to non other than God.
My argument against God was that the universe seemed so cruel and unjust. But how do I get this idea of just and unjust? A man does not call a line crooked unless he has some idea of a straight line. What was I comparing this universe with when I called it unjust.
C.S Lewis, Mere Christianity.
As Lewis puts it, there can be no idea of what is bad without first an idea of what is good. And as demonstrated earlier, the idea of what is good cannot be based on human related opinions. I answer that the reason why murder is a bad thing yesterday, today and tomorrow is because the moral law is grounded in the very immutable nature of God. For the immutable nature of God which forms the basis of what is known as good is altogether unchanging.
And the deviation from that standard of goodness is what is called bad or evil or sin. God is the same yesterday today and tomorrow, since an infinite being such as God by definition is pure act i.e. no potentiality but only pure actuality. God is pure act and in Him there is no potential to be evil or to sin, for the goodness of God is infinite. And the existence of evil in this world is not God deviating from His own infinite standard of goodness, but rather human beings deviating from His standard of goodness.