Why might democracies be less warlike than other regime types?

Two early and related ideas:

Thomas Paine ([3] p. 169): “What inducement has the farmer, while following the plough, to lay aside his peaceful pursuit, and go to war with the farmer of another country?”

Immanuel Kant ([1], p. 122): “if the consent of the subjects is required to determine whether there shall be war or not, nothing is more natural than that they should weigh the matter well, before undertaking such a bad business.”

This idea has influenced policymakers of different political persuasions.  Is there a rational choice/strategic theory for the democratic peace?  This lecture discusses various alternatives.

First, we study the fear motive for war. The median voter might be a coordination type who wants his country’s leader to be dovish against a dovish opponent but aggressive against an aggressive opponent.  This captures the Kant/Paine idea but also Schelling’s idea that aggression might arise out of fear.  These incentives imply that democracies are more responsive to aggression that other regime types.  A second possibility is that a leader can survive with the support of the “mob” (which has the same preferences as the median voter) or with the support of an elite that favors war. The leader loses power if he is weak in the face of aggression (no one supports him) but survives if he is aggressive even when an opponent is not (the hawkish elite support him).  This kind of regime is more aggressive than a dictatorship.  Data support these these comparative statics.

Second, we study the greed motive.  The leader of country may get a disproportionate share of the spoils of war should his country win but not suffer a large cost if it should lose.  He has a bias. If both leaders are biased, it may be impossible to avoid inefficient war even if transfers are possible.  But if both leaders are unbiased then transfers can resolve conflict and may even be unnecessary.

Third, bargaining may devolve into a war of attrition.  A democratically elected leader suffers greater “audience costs” if he backs down.  This makes him a tough bargainer and his opponent correspondingly weak.  A player may even deliberately “talk up” his audience costs to become a tough bargainer.

Here are the slides.