International conflict is related to many other political and economic phenomena. So even if you are not directly interested in wars, you might need to understand and model them to understand a different question. An example of this is state-building.
Charles Tilly famously argued that ‘states made war, and war made states’. The argument says that in order to finance their wars, kings and queens of Europe needed to build up a proper taxation infrastructure or they faced elimination in an international war by their more successful counterparts. There are some recent attempts to formalize and build on these ideas. A prominent paper is by Besley and Persson, who take wars to be a ‘common interest public good’. Their model confirms Tilly’s argument: they argue that a higher demand for public goods leads to investment in state capacity. However, there are at least two issues to think about here.
First Besley and Persson’s argument is predicated on the assumption that war serves the common interest. Is this really a good assumption? The assumption that defense is a public good is widespread. For instance, it appears in Bruce Bueno de Mesquita, Morrow, Siverson ans Smith in their attempt to find institutional roots to the democratic peace puzzle (i.e. that democratic states do not appear to fight each other as much as other pairs of countries). Yet are war and defense the same concepts? Does war really serve the interest of the group in power as well as the interest of the group out of power? A long line of research started by Robert Jervis argues that the distinction between offensive and defensive capabilities is important. Thus the impact of a war for the aggrandizement of the Bourbon dynasty could be quite different from a war started in the fear of invasion to impose a regime change.
Second, it is also questionable how much it is civil rather than international war that plays the key role in state-building. For instance, looking at the case of Britain in depth, James Robinson and Steven Pincus seem to find very little correlation between international war and key moments in state building. These moments arose more out of local political considerations, and often in civil war.
So is interstate war related to state-building? If yes, through what mechanisms? Is war a common-interest public good? These are interesting and important questions to ponder.