Neil Uchitel at Digital, Finger & Co posts a review of Dave Grossman's 1995 book On Killing. The review is featured on Simon's Showcase, the successor to the now defunct one hosted by N Z Bear. While I lack the expertise to rebut either the book or the review, my sense is that it is only telling a fraction of the story. However, the penultimate paragraph caught my attention as being worthy of an answer and within my sphere of expertise:
From a broader philosophical point of view, however, On Killing is not only a necessary work illuminating the inevitable guilt associated with the act of killing, but more abstractly (and I believe, more importantly), the inevitable guilt associated with hate itself. We all have heard the scripture "Whosoever hates his brother is a murderer..." (I Jn. 3:15). What Grossman does is provide a very clear neuropsychological reason why this is true. It causes one to think that perhaps Christians don't understand true guilt very well. They generally see it as the bad feeling they got from breaking some arbitrary rule, like "no smoking" or "55 MPH Maximum Speed", or perhaps "Thou shalt not covet..." But Grossman's thesis implies that no, the kind of guilt he is talking about is much deeper, much more primal. Killing one's fellow human being is a moral violation of enormously existential proportions, one that even the military with all of its contextualizing structures has only limited success in assuaging. It causes one to think that perhaps the "guilt of sin" that the Gospel aims to remove is not merely that of breaking some arbitrary moral rule(s), but rather of guilt caused by exercising ourselves in matters too high for us -- matters of life and death. That is, not only does God not want us to hate people because its "wrong", but perhaps it is wrong because by "killing" others in our minds, we stain ourselves with "blood-guilt", causing us both spiritual and psychological damage of which we are not even aware. If this is true, it definitely casts a new light on the meaning of the word "redemption".
There are a few things that bear commenting on here:
First, since this is in a military context, the conflation of killing with hatred seems particularly inappropriate. The main thesis of the book he is reviewing is that soldiers are generally unwilling to kill their enemies and must be specifically trained to do so. Furthermore, not only is killing in warfare permissible in the New Testament (Matt 8:9; Luke 3:14), there are times when it is positively commanded (Luke 22:36-38; Rom 13:4). This is in addition to all of the obvious passages in the Old Testament, which some Christians find controversial. So hatred is clearly not a factor either practically or theoretically in most military killing. Since Neil professes to be a Christian, and is obviously a thoughtful one, I find it extremely problematic that he makes this fundamental, but all too common error.
But even apart from the military aspects, the notion that there is "inevitable guilt associated with the act of killing" cannot be justified from a Christian perspective. The commandment is against murder, or unjust killing, not killing as such. Capital punishment is instituted in Gen 9:6, and, as the passage from Romans cited above indicates, this authorization continues into the New Testament era. While we are cautioned against taking vengeance in both Testaments, it is simply not the case that killing in a just cause is universally condemned.
This brings us to the "neuropsychological" explanation. As I admitted above, I lack specific expertise in this area, but it seems to me that claiming such an explanation is "deeper" or more "primal" an account of sin than the more traditional deontological approach lacks support. It would be just as valid to argue that the psychological effects were providentially provided to support the moral principles.
Finally, what I consider the most troubling quote in the piece, is the suggestion that "Christians dont understand true guilt very well. They generally see it as the bad feeling they got from breaking some arbitrary rule, like 'no smoking' or '55 MPH Maximum Speed', or perhaps 'Thou shalt not covet...'." The first two are, of course, arbitrary to the extent that they deal with prudential rather than moral concerns. But even prudential concerns are not quite arbitrary in the absolute sense. They are negotiable, but usually based on some measure of accumulated wisdom, which should not be dismissed out of hand.
But more telling is the inclusion of the final example, which is a direct command of God. Is this a mere arbitrary rule like the other two? Or is there a fundamental truth that about human nature and its relation to God's will that we are supposed to derive from the 10th Commandment. Its inclusion in the same list as "Thou shalt do no murder" implies the latter. If Christians in general have indeed come to a pass where they regard this as mere "arbitrary moral rule(s)" then it is small wonder that our voice has been muted in the culture at large. But the problem will not be solved merely by appeal to emotional or biological explanations. Ignorance of God's will and the character of sin can best be remedied by immersion in the tradition of Christian thinking, beginning with the Bible but extending through two thousand years of accumulated wisdom.
I commend Mr. Uchitel for his attempt to bring Christian precepts to bear on worldly problems. But I think he has got things somewhat backward if he expects to derive moral principles from observations of human behavior, however insightful they may be in themselves.