From a practical standpoint, we could deliberate all day as to specifically what a moral and/or ethical perspective might be in relation to Numbers 31. So, as Christians, I think the best approach in explaining this passage is to evaluate it from within a Biblical framework rather than one relying mostly on a secular or philosophical one.
Good summation of the passage, so I wont elaborate upon it.
From a Biblical standpoint, we cant really say that the children were innocent. Sure, technically, they were innocent, if by this we view it through the lens of modern, secular human rights. But, since we are instead applying the bible as our conceptual framework, we cant say that the children were innocent. It seems to me that what we see in this passage is the ramification of a national sin on the part of Midian, one which invokes the penalty of Gods wrath upon all of the offending people, as seen in the 1st Commandment,
for I, the Lord your God, am a jealous God, visiting the iniquity of the fathers on the children, on the third and the fourth generations of those who hate Me (Exodus 20:5 NASB). Here we see that God may apply His penalty for idolatry upon an inter-generational set of people.
What we also need to see here is that the girls did not receive differential treatment simply because they were girls, or even because they were virgins, but that even though they were ALSO under the death penalty, they could be spared willfully by Israelite men for the purpose of becoming sexually untainted wives. Otherwise, they too were under the ban.
Actually, you may be thinking of Deuteronomy 24:16, specifically, a verse that reflects the penal code for personal sins of parents wherein children are not to be inculcated along with the parents. However, in looking at Midian, we should remember that what Midian did as a nation by pulling Israel into idolatry and sexual sin was not done at merely a personal level, so everyone in Moab was subject to the penalty of the transgression. (We should keep in mind also that men of Israel who consorted with the women of Midian and Moab were also subject to the death penalty.)
Same as above, Sam. I know that from todays perspective, it seems really harsh and/or inconsistent ethically, but God still today has and expresses a personal trait of Holiness, and as a derivative of that, there also exists a Holiness code over His creation. We dont see that code applied very often in Christianity because, for the most part, Jesus absorbed those penalties for us, as long as we are walking in the New Covenant faith.
It is one explanation, but I think the ongoing presence of Gods Holy Being and His Holy code over creation is what explains the intensity and the extent of this passage the best. The young girls simply got a second chance because they had utility, which sounds crass, but their sexual purity was the *only* thing that made them valuable.
Actually, Deuteronomy 20 refers specifically to warfare limitations which Israel was to abide by when going to war with people of far off nations, and not the peoples belonging to one of the SEVEN nations nearby which God had specifically delineated for complete elimination (see Deut. 20:14-18).
Again, I agree that all of this is tragic and sad, particularly since in our modern times weve been able to articulate what seem to be superior ethics. But we should be aware that todays ethical systems are founded on principles that are either not self-evident to all, or on highly contested ideologies.
Peace
2PhiloVoid