Edited and written by David Gordon, senior fellow of the Mises Institute and author of four books and thousands of essays.

Fall 2006
Volume 12, Number 3

There is No Justice in Preventive War

Jeff McMahan, "Preventive War and the Killing of the Innocent" in The Ethics of War: Shared Problems in Different Traditions. Edited by Richard Sorabji and David Rodin. Ashgate, 2006. Pp. 169-190.

Jeff McMahan's subtle article is an outstanding account of the morality of preventive war, and not incidentally a sharp condemnation of the Iraq war. McMahan cites a revealing statement from Vice President Cheney in October 2003: "some claim that we should not have acted because the threat from Saddam Hussein was not imminent. Since when have terrorists and tyrants announced their intentions, politely putting us on notice before they strike?"(p.171)

McMahan points out that Cheney here concedes that Iraq posed no imminent threat, but takes this to be irrelevant. If the threat was not imminent, then the American invasion was a preventive war. And this is illegal under international law.

But should it always be illegal? Does morality sometimes permit preventive wars? In the Iraq case, there was no reason to believe that Saddam had WMD, much less that he proposed to use them against us. But suppose that there had been very good evidence for these things. Is it then so obvious that a preventive war would have been morally wrong?

In response, McMahan points out that "justifications for preventive war as they are actually asserted tend to be overly permissive in their implications. . .when the Bush administration sought to justify the second Iraq war. . .it appealed primarily to three claims: that Iraq possessed weapons of mass destruction, that it had a recent history of aggressive war, and that it had indulged in bellicose rhetoric directed against the USA. But. . .all of these claims were also true, mutatis mutandis, of the USA itself, with the Bush administration particularly noisy in issuing threats against Iraq, Iran, and North Korea. But no one in the administration would have conceded that any of these countries had a right to attack the USA in preventive self-defence." (p.174)

Even if there are permissible cases of preventive war, then, it is difficult to come up with clear criteria that do not "justify" too much. And there is a further problem. Each nation considers its own actions morally justified: the American government, e.g., never thinks that it makes unjust threats to others, although much of the rest of the world would disagree. Is it not likely, then, that even if clear and consistent criteria for permissible just wars were formulated, they would in practice be misapplied? "Acknowledgement of the permissibility of preventive war would, in practice, as Michael Walzer has argued, be likely to encourage to encourage the initiation of wars wrongly believed or claimed to be necessary for national self-defence."(p.175)

The problems with preventive war go deeper. "According to the traditional theory of the just war, what makes a person non-innocent, or morally liable to attack in war, is actively posing a threat to others."(p.178) So long as soldiers of an "enemy" nation do not attack us or prepare to attack, they count as innocent. The just war criteria do not allow "speculative" attacks on people, because of surmises that they will in future pose a danger. "Stated in more general terms, the central objection to preventive war is that it is necessarily indiscriminate---that is, it is war waged in the absence of legitimate targets. . .if it is right that preventive war, of its nature, targets those who have as yet done nothing to make themselves liable to attack, it follows. . .that prevention of future aggression cannot be a just cause for war."(p.178)

McMahan does not stop here. He is a consequentialist and rejects the traditional theory. His own approach is more permissive: it allows preventive war under certain conditions. I think that he has adopted a mistaken moral theory; but for our purposes his mistake is fortunate. Even on his more permissive view, it turns out that in practice preventive wars are almost invariably ruled out.

I shall not attempt to summarize his characteristically ingenious thought experiments. In sum and substance, he concludes from them that if you know that someone intends to attack you, you may act against him even before he has done anything to implement his plan. "I [McMahan] believe. . .that the mere formation and retention of a certain intention---both of which are mental acts---can be a sufficient basis for moral liability to preventive action." (p.184)

McMahan here opens a door he immediately proceeds to close. We can in practice rarely if ever have sufficient certainty about someone's intention to justify preventive action: "because intentions are private and not directly accessible to others, the evidence for the presence of a wrongful intention is almost always insufficiently conclusive to provide an adequate basis for preventive action. If we possessed an intentionometer that would infallibly detect other people's intentions and gauge their strength, the moral and legal status of preventive defence would be profoundly different."(p.185)

But not even this would be enough to justify preventive war. Suppose that we infallibly knew that the leader of an enemy nation secretly intended to attack us six months from now. He has so far, though, given no orders for aggressive action. We could not justifiably attack his forces, since they have neither done nor intended any harm to us. It would not be a good answer to this that the soldiers will be likely to obey orders from him to attack us. "Virtually all soldiers at all times have been strongly disposed to obey orders to go to war irrespective of whether the war has been just or unjust, Indeed, as Stanley Milgram's experiments in the 1960s showed, most people are strongly disposed to obey an order to inflict unjust harm on others, provided the order is issued by someone they perceive to be a legitimate authority. We should not conclude that most people are therefore liable to preventive defence." (p.187)



Image of Mises Coat of Arms Ludwig von Mises Institute
518 West Magnolia Avenue
Auburn, Alabama 36832-4528

334.321.2100 Phone
334.321.2119 Fax
AOL-IM: MainMises

Contact us button
Mises.org Menu