I was reading an entry from Victor Reppert's blog (Reppert being a noted apologist), where he mentioned that just war theory, specifically prohibitions on what you could do during a war and afterwards, was a Christian invention.

I thought that was interesting, albeit a little implausible, so I looked up just war theory on Wikipedia, and sure enough, it says that while the concept of justification dated as early as Cicero (so, c. 75-50 BCE), the idea as it stands now (and to which Reppert refers) does come from Augustine of Hippo and Thomas Acquinas.

My knowledge of history is limited to the Roman Republic/Empire, and to Greece via Thucydides and the classical philosophers, so I couldn't think of a specific instance where the losing side was afforded any inalienable rights: any concessions given were at the pleasure of the winning side. But I could have just as easily missed some event or philosopher at the time proposing such a thing.

The general definition of a "just war" from the Roman Catholic Church is mentioned in paragraph 2309 of the Catechism of the Catholic Church:

The strict conditions for legitimate defense by military force require rigorous consideration. the gravity of such a decision makes it subject to rigorous conditions of moral legitimacy. At one and the same time:

  • the damage inflicted by the aggressor on the nation or community of nations must be lasting, grave, and certain;
  • all other means of putting an end to it must have been shown to be impractical or ineffective;
  • there must be serious prospects of success;
  • the use of arms must not produce evils and disorders graver than the evil to be eliminated. the power of modem means of destruction weighs very heavily in evaluating this condition.

Is this definition a novel formulation of what constitutes a just war? Were there similar definitions held before Augustine?

  • 4
    Sun Tzu in the Art of War states that a ruler should define and justify any wars to his subjects. It would not be a stretch to say that this as a "just war" argument. Oct 26, 2011 at 8:28
  • Is this definition a novel formulation of what constitutes a just war? ...kind of random and call me crazy, but I believe that the major precondition for a "just" war is that nobody kills anybody. Jan 20, 2016 at 13:53

1 Answer 1


I found a rather lengthy discussion on this topic at the Internet Encyclopedia of Philosophy. It points out that the concept is most likely to evolve between two culturally similar enemies. The shared values between these two sets of people will result in a situation where "they implicitly or explicitly agree upon limits to their warfare".

The Introduction suggests that just war theory has a long history. It alludes to Homer's *Illiad" and the Bible as sources of examples. The article overall makes for pretty interesting reading. It even expands to discuss the concept of "just conduct within war", in which it basically states that if war is inevitable, there should be certain principles that should be adhered to by the participants.

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