(2) A connectivity effect during relatively stable periods played a crucial role in the System to produce systemic wars in response. When cycles are used as the unit of analysis, it is possible not only to identify the above discussed patterns in the war dynamics of the System but also to determine that during relatively stable periods, the average sizes of non-systemic wars were initially relatively small and then increased, until what I refer to as a tipping point was reached, after which they began to decrease to approximately a size of ‘zero’ shortly before the outbreak of a systemic war.
Figure 5: This figure shows a schematic representation of a single cycle: a relatively stable period, during which an international order is in place, is followed by a systemic war, when an ‘upgraded’ order is implemented. During relatively stable periods, the System is in a subcritical condition and produces non-systemic wars, whereas during systemic wars, the System is in a critical condition.
It is possible to observe this typical dynamic by defining the sizes of wars not in terms of severities (as historians normally do, see Levy) but rather by defining size in terms of ‘fraction’. I define ‘fraction’ as the number of Great Powers that participate in a war divided by the total number of Great Powers in the System at that point in time. The size of wars defined in terms of fraction can be considered a measure of the size of the ‘cascades’ – ‘domino effects’ – that the System produces relative to its total size.
Figure 6: This figure shows the size-development of Great Power wars the System produced during the period 1495-1975 (based on Levy). To identify the cycles, I show the moving average of the sizes of five successive wars (systemic and non-systemic). The arrows point to the tipping points of each cycle. Because of the limited number of non-systemic wars during the fourth relatively stable period, the tipping point of this period cannot be established. The red shaded ‘areas’ in the figure concern the periods, following systemic wars, when the System was too highly connected to release tensions and resolve issues, and consequently ‘charged’ itself for a next systemic war. ‘SW’ stands for ‘Systemic War’. Basic data from Levy.
I assume that the decrease in the average size of non-systemic wars once the tipping point of a relatively stable period is reached can be attributed to the connectivity of the network of issues (security related matters between states), of which states themselves are integral parts. The high connectivity of this network results in ‘local’ stability of states because states become increasingly entangled in a web of issues, and the significance of incoming ‘signals’ – for example, threats to states – diminishes.
I argue – an assumption based on Watts – that states’ war decisions can also be considered binary decisions with externalities to which thresholds apply. States and their issues thus form a network of ‘binary switches’ and are ‘yes/no’ in war with other states. In a series of simulations, Watts observes that the sizes and frequencies of cascades in networks with similar basic structures are – as seems the case with the sizes and frequencies of non-systemic wars – determined and shaped by the connectivity of the binary network, and thresholds that are applied to switch to another ‘state’.
The increasing stability of states in the issue-network is not without consequences, however. I argue that although states become more stable because of their increased connectivity in the issue network, tensions are still produced at an accelerating rate. Consequently, once the tipping point of a relatively stable period is reached, (unresolved) issues and tensions accumulate in the System until the next systemic war. The System, in other words, is ‘charging’ once the tipping point is reached and builds up a ‘tension release deficit’. However, at a certain point in this accumulation process, the ‘clusters’ – networks – of unresolved issues and accompanying tensions ‘connect’ – percolate through the System – and cause the System to become critical. At the critical point, the correlation length of the System has become ‘one’, and all states and their issues become connected. At the critical point, a small incident can trigger a systemic war.
During systemic wars, tensions that are released are used to ‘design’ and implement ‘upgraded’ international orders that again allow for lower tension levels in the System.
To be continued.