This is the third post in the series I started earlier (I, II) but not the post I promised. That's still in the works.
Rabbi Yitzchak Blau wrote an article a few years ago titled "Ivan Karamazov Revisited: The Moral Argument For Religious Belief." In it he dealt with the propensity of Kiruv organizations and educators to use the moral argument as a reason for believing in G-d. Basically the argument work like this: if G-d doesn't exist and didn't determine morality in the Torah, what makes something moral?
I remember watching a kiruv video on Tisha Ba'av a few years ago where the Kiruv professional made the same argument. If there is no G-d, why was Hitler wrong? Why is it wrong to commit genocide? That argument struck me as contrived back then, and even more so now.
But this post isn't going to try to explain the basis of an independent objective morality that does not depend on G-d. I will argue that such a morality must exist for the Torah to be binding and that morality can fill in the gaps where Halacha abstains.
One of Rabbi Blau's objections to this argument is that the solution doesn't solve the problem. Sure G-d can define morality and his Divine commands could be the definition of morality, but why are we bound by his commands? The fact that G-d commands us to do something cannot be a normative basis in itself. Why must we follow that command? R. Blau recounts Rav Saadiah Gaon's response to this problem: man is obligated to obey G-d as an act of gratitude for all that G-d has done for us. It seems Rav Saadiah's solution presupposes the existence of a morality that exists independently of G-d's command.
I don't see any other way. I'd like to make three points. For G-d's command to be binding there must be a morality that exists outside of his command. The morality need not exist independent of G-d, but it must exist outside of G-d's command. Furthermore this morality must be objective. If not, why can't any individual claim he isn't bound by G-d's command because his own morality doesn't dictate a normative reason to be obligated to listen to G-d's words? Last, that objective morality must bind us. If we can choose whether to be moral, we can choose whether to obey G-d. Therefore that morality must impose obligations upon us or the Torah isn't universally binding on Jews.
Moreover, it seems as if this morality is accessible to humans without divine intervention. Practically it is quite difficult to disentangle G-d's command from his epistemic guidance on moral issues. G-d theoretically could inform us that our moral intuitions point toward listening to G-d's command, but most divine statements are framed as commands and not guidance. So we must be able to determine our moral obligations without Divine assistance.
So if an independent morality exists, and humans are capable of determining their moral obligations without divine assistance (through reason), how does that affect Halacha? Is Halacha threatened by an outside objective morality? I don't think so, or at least not directly. Once we have a moral reason to listen to G-d, his command become binding, assuming the divine command doesn't contradict the original moral reason for G-d's command becoming binding. So, for example, if we are required to obey G-d because of gratitude, then nothing G-d commands can require us to contravene gratitude since that would undermine the entire basis of our obligation in the first place.
On the other hand, it is possible that G-d's binding command could order us to act against morality in other cases. If we are bound by G-d's command as well as by objective morality, then it becomes a question of which to choose. A reasonable person can choose the former, at least because G-d might be more qualified to determine what objective morality demands of us. So Halacha could trump morality in vast majority of cases.
But what about where Halacha does not impose an obligation upon us? To use a classic example, Halacha set up two different tracks about how to act depending on whether one's associate is a Jew. For example, if a Jew's ox gores another Jew's ox, he does not need to pay the full extent of the damages (subject to the damaging ox's status), but a non-Jewish owned ox must always pay the maximum damages. The Gemara itself in Baba Kamma recognizes that the disparity is morally problematic (at least from the perspective of the Roman auditors who were responsible to review Halacha).
If one posits that objective morality demands that a Jew not treat a fellow human being differently based on his religion, he could argue that a Jewish court should not impose different standards. The bare Halacha does not mandate that the Gentile owner of an ox must pay the full damages, only that Halacha does not afford him the leniency given to the Jew. There is no Halachic obligation to require a non-Jew to pay more than a Jew; there is just an allowance to be lenient by a Jew. In other words, the Halacha is just a minimum not a maximum. We can choose to give a break to a non-Jews as well. (If my Halachic analysis is incorrect, please let me know).
Since G-d did not command us to require full damages from non-Jews in all cases, we have a gap in the law. The law does not require us to act either way. In that case independent morality comes into play and if it requires treating non-Jews and Jew alike, non-Jews should no longer be obligated to pay complete remuneration.
Another example is telling Loshon Hara about non-Jews. A few months ago I had a long argument with Ed about whether it is acceptable to tell LH about Blacks. Ed argued that Halacha prohibits telling LH about Jews, but not non-Jews (which is true). Therefore we are allowed to denigrate Blacks. I disagree because the Halacha is setting a floor, not a ceiling. It does not command us to slander Blacks, but merely allows it. I believe the independent morality mentioned above can be used to fill this gap. If it is morally wrong to slander anyone (Jew or non-Jew) that morality requires us to forgo telling LH about non-Jews.
Basically the interaction between Halacha (i.e., Divine command) and morality can be treated like the relationship between federal and state laws. Federal law preempts state law, so whenever the two conflict, federal law reigns supreme. But where federal law abstains and doesn't dictate policy, state laws can fill the gap. So too with Halacha and morality. Halacha preempts morality, but where Halacha states no command, morality dictates what we can do.