Just War Theory and Other Philosophical Responses to Warfare (A Footnote on Aquinas, Erasmus, and Machiavelli)

(Warning: a rambling disquisition about the point of just war theory in history. Tries to articulate some thoughts I've been nursing for the last couple of months, and some things I've tried to say in my class on political philosophy and international relations). 

How should one respond to the fact of war? I do not mean how we ought to respond to this or that war, but about the enduring fact that human beings engage in warfare: what should we do about this fact, at the most general level, if anything? And in particular, what constitutes a proper philosophical response to the fact of war?

One common response to the fact of warfare is articulated by the theory of just war. Just war theory presupposes that war is an unfortunate but sometimes unavoidable aspect of the human condition: given some general facts about human psychology (for example, the fact that at least some people lust for power or strongly believe that particular ideologies must be imposed on others), we must expect war to flare up from time to time, though its frequency may wax and wane for a variety of reasons (demographic, technological, cultural, etc.). Yet some of these wars will be justifiable: there will be good reason for (some people) to fight them in order to protect important values. The proper response to the fact of warfare thus involves articulating the principles and rules that distinguish between justifiable and unjustifiable wars (and between justifiable and unjustifiable conduct in war), and appealing to or forcing those who engage in that practice to regulate their conduct according to these principles and rules; and at least the first task necessarily involves philosophical reflection.

The ideal here is not the elimination of war, but the reduction of unjustifiable war through the moral (and sometimes legal) regulation of the practice. And though this regulation may take institutional form (as it does, imperfectly, nowadays), it need not: all the just war theorist presumes is that most people are relatively receptive to moral argument, at least when such moral argument appeals to relatively noncontroversial principles and is presented in a clear way. And even if such appeals sometimes fall on deaf ears, the just war theorist assumes that they are not entirely ineffectual. One can appeal to the conscience of those in power, even if sometimes they have trouble hearing its voice, or at least force them to pay a decent respect to the opinions of others, and one can train those who actually fight to be responsive to moral precepts that constrain what they can do in the heat of battle.

The basic principles of just war theory seem to have a certain universal appeal, given that they have changed little since Aquinas articulated them in the 13^th century. (And he was merely systematizing ideas that were even older, going back to Cicero and the Stoics in the late Roman Republic). We still discuss ius ad bellum in terms of the basic triad of proper authority (who can authorize a war?), just cause (is there a good reason to fight, and in particular a reason that can justify the collective use of armed force?), and right intention (is the just cause merely a pretext for more nefarious purposes, or do the people waging war genuinely intend to protect some important values by going to war?). Other principles – like “reasonable chance of success” – sometimes enter the discussion, but the basic framework remains ancient. Witness the debate about the recent intervention in Libya, for example. Disagreement about the morality of the intervention revolved around the questions of who had the authority, if anyone, to permit the use of armed force against Gaddafi’s government, whether Gaddafi’s actions to put down a rebellion against his government gave other countries a good reason for engaging in war against him, and whether NATO members genuinely intended to protect Libyan civilians and/or help the Libyan rebels overthrow an oppressive regime (or were, on the contrary, acting to secure control over Libya’s oil or Western influence in the Middle East). Similarly, debates about the morality of particular tactics in bello (e.g., the use of precision munitions to attack particular people in urban areas) all revolve around the basic triad of principles of innocent immunity (is the target a civilian or a combatant?), proportionality (are the means proportionate to the end, or are they “overkill”?), and double effect (are the deaths of civilians a genuinely unavoidable result of the use of proportionate means?). Though the full articulation of the principles of ius in bello is of somewhat more recent vintage (they are more sketchily described in Aquinas than the principles of ius ad bellum, for example), they are still quite old and broadly accepted.

But though the basic principles of just war theory are widely accepted, the fact of disagreement obviously indicates that their application is much more controversial. The more one moves from broad principles to specific rules and even more to particular judgments the less arguments about the justice of particular wars or tactics will be convincing. Arguments come to depend on distinctions that are far less obvious and much more contestable. For example, the US Air Force consistently argues (and I’m sure mostly in good faith; as far as I know, American soldiers do receive explicit training on the principles of just conduct in war) that its use of precision munitions respects all the basic principles of ius in bello: such munitions are used only against people which intelligence indicates are “combatants” and responsible people attempt to minimize “collateral damage” (i.e., apply the proportionality and double effect principles). Yet many people vocally disagree with them about all aspects of this argument, including the weight that should be given to the evidence of combatant status (what is the acceptable false positive rate for a target?) and whether the use of 500 pound weapons in urban areas represents due care for the lives of non-combatants (what is the acceptable rate of civilian death from attacks on genuine military targets?).

The problem is not that there is no right answer to these questions, but that no particular answer can depend on premises that are all widely acceptable. Many if not most positions can muster plausible arguments (I get a glimpse of this every year when I ask my students to write essays applying the principles of just war to various recent military conflicts). Even sincere attempts by serious and well-trained thinkers to apply these principles to particular conflicts lead to ambiguous results. When one reads Vitoria’s exhaustive examination (in the 16^th century) of what would count as a just cause of war against the natives of the Americas (and hence would justify conquering them and taking their land), it is hard to say for sure whether he supported or opposed the conquest; though in private made it clear that he was appalled, he thought that there could be (and perhaps were?) circumstances in which the conquest would have been justified.

The pervasiveness of disagreement, and the fact that such disagreement is necessarily entwined with important (even existential) interests tends to make moral argument about just war appear as a form of rationalization, and worse, as legitimating the designs of the powerful. The suspicion arises that in trying to distinguish between justified and unjustified forms of war we merely enable more warfare; and that we would all be better off if the considerable intellectual energy spent on making these distinctions were instead spent on delegitimizing warfare as such. Already in the 16^th century, when the School of Salamanca was at the height of its influence (the Valladolid debates on the justice of the Spanish conquest of the Americas were not just for show!) and just war theory had evolved into a highly sophisticated discourse, there were people who thought precisely that. In his Dulce Bellum Inexpertis, Erasmus railed against what he saw as the enabling role of theologians in justifying too many wars. For him, just war reasoning was corrupting: it turned theologians and philosophers into advocates of their patrons’ predatory projects. The correct philosophical response to the fact of warfare, in Erasmus’ view, was not to help regulate it by articulating the principles and rules that can justify particular wars or practices within wars, but to deploy the full power of rhetoric to depict the horror of warfare and to delegitimize it as much as possible. (It is worth noting that the Dulce Bellum Inexpertis was a sort of 16^th century best seller. The printing press was still relatively new in Europe, and Erasmus was very good at making use of it to publicize his views).

The point is not that Erasmus thought that no war could ever be just (he does suggest here and there that some wars could be justified), but that asking which wars are just is (most of the time) the wrong question, since most wars will not be just. Intellectual energy is better spent delegitimizing warfare as much as possible by depicting its material and moral costs as vividly as possible, denouncing its general injustice, and indicating potential alternatives. (This is implicitly an argument about the “responsibility of intellectuals,” though of course the point is never put that way by Erasmus). In this way, if wars must be fought, they will tend to be fought less often, and with more restraint; the use of rhetoric to delegitimize warfare as such will if nothing else tend to “ratchet” up the restrictive force of just war principles, increasing the rhetorical cost that must be paid to start or wage a war. Whether this is in fact the case is difficult to tell; there does seem to have been a gradual, if haphazard, “tightening” of the restrictive force of just war principles over time, though whether this “tightening” is at least partly due to the efforts of people like Erasmus is anybody’s guess. For example, whereas Aquinas in the 13^th century thought that almost any “wrongdoing” that could not be redressed by the political authorities of a single political community could constitute a just cause of war, we now treat suspiciously any form of warfare that is not obviously defensive. And this “tightening” of the principles of just war has been correlated (I’m not claiming causality, however) with apparently large declines in the overall frequency and murderousness of war. (Yes, there are exceptions, and very long-term trends obscure significant variation over shorter periods of time. But the overall trends are striking, despite the greater destructiveness of modern technologies of warfare. At any rate, one only has to read Thucydides History of the Peloponnesian War to understand that the modern era is not particularly inhumane in its way of waging war).

The 16^th century also gave rise to a very different response to the fact of warfare. Here the exemplary figure is Machiavelli, and the problem is not what to do to reduce warfare (should one help regulate it, or delegitimize it?), but how to use warfare to accomplish important goals. Warfare is not seen as a uniquely awful experience, but as a tool of politics; and one must study “The Art of War,” not because one ought to avoid war, but because one must learn to use it efficiently. Machiavelli (among others, though he most of all) wants to study the “economy of violence,” in Sheldon Wolin’s useful phrase, to put war to use, and in particular to put it to use for purposes that are internal to political life (the achievement of power, the foundation and preservation of political communities, etc.). Machiavelli’s thought is especially original not so much because he wants to study the economy of violence, however (there are many precedents, and Machiavelli’s advice in this respect, though generally acute, is not always great), but because he thinks that the standards by which we must judge the use of violence are themselves internal to the practice of politics: greatness rather than goodness. The point is to learn to do memorable and admirable deeds, and the most admirable deeds are those which produce lasting authority structures (founding religions and political communities, for example), not those that are most in keeping with conventional moral rules (or are accomplished with the least amount of violence). (I might write more on this point. It’s something I’ve been thinking about).  But even if one disagrees with Machiavelli that these are legitimate goals, and that reducing warfare is much more important, one might still think that doing so requires understanding the economy of violence and using it judiciously: that seems to me to be the genuine moral core of “realism” as a kind of consequentialist theory. 

Though the Machiavellian response is not a direct reaction to the development of just war theory, it is nevertheless a logical response to the same concerns that led Erasmus to move away from just war reasoning. It’s interesting to me that the European experience of the 16^th century produced these entirely divergent responses to war, despite the fact that all of the writers who were operating in these traditions had similar understandings of what war entailed (war was after all a very common experience in their world). None of them were especially naive about human beings and their limitations, and many had real influence with those in power. Yet these three responses seem to be fundamentally different, and the difference is not always rooted in radically different understandings of human nature (though they do differ on this point, especially Erasmus). In my class, I sometimes put the point in slogan form: just war theory says (about war) “regulate it,” Erasmian pacifism says “delegitimize it,” and Machiavellian political science says “study and use it.” 

Yet which of these responses is the best one? And how are they related to one another? Are they complementary responses, such that a division of intellectual labor between their proponents is possible, and capable of promoting important values over time? (Just war theory and Erasmian-style pacifism do seem to me to be related in something like this way, but to be in tension with Machiavellian political science). Or are they ultimately incompatible, so that we must choose among them? And does the development of just war theory typically necessarily generate, in a “dialectical” fashion, these alternative responses to war? I suspect that it does: as just war theory becomes more complex, it comes to seem more futile, giving rise both to Erasmian-style “delegitimize it” responses Machiavellian-style “study and use it” responses, and yet it never fully disappears; and perhaps just war theory itself becomes more relevant after periods where both Erasmian and Machiavellian responses seem to fail (perhaps the period after WWII).

[Update 9/22: fixed some typos and made some minor wording changes]