18 International Relations Theory of War
international systems is defined through four components of war: the
number, frequency, duration, and lethality of wars in which the polar pow-
ers constituting the system are involved, in the six instances of the three
possible polarity models. The assessment was done by examining each
interstate war in which the polar powers participated, in the way they are
defined in the book, in each of the six instances of the three system models
in 1816–2016. The stability of international systems is defined according to
four parameters.^18
The first is the number of the three war types, a parameter that examines
the number of each of the three types of wars in each of the three systems.
The variable will be examined by adding up the three types of wars sepa-
rately: (A) central wars—which involve all polar powers constituting the
system, (B) major wars—involving only some of the polar powers, and
(C) minor wars—in which one of the polar powers fights against a country
or countries that are not polar powers.
The second is the frequency of wars, a parameter that examines the fre-
quency at which wars of the three types broke out in each of the three sys-
tems. The parameter will be examined by calculating the length of each of
the three systems in years, or the three polarity models, including the total
number of instances of them, by calculating the number of years of war of
each of the systems, and by finding the percentage of years in which the
three types of wars occurred out of the total number of years in which the
system being assessed existed.
The third is the average duration of wars, which assesses the average dura-
tion of the wars in days in each of the three system types. The variable will
be assessed by calculating the total number of days of all wars fought in
each of the three systems or the three polarity models and dividing this
result by the total number of wars fought.
The fourth is the severity or lethality of the wars, which assesses the total
number of casualties in battle of the subject wars in each of the three sys-
tems being assessed. This variable will be assessed by calculating the num-
ber of casualties in battle in each war and totaling the number of battle
casualties of all wars fought of the three types of wars in each of the three
systems.
Three values will be used for describing the stability of each of the three
possible polarity models relative to the two other polarity models. A sys-
tem will be considered destabilized when the values of the four parameters—
the number, frequency, duration, and lethality of wars involving the polar
powers constituting the system, primarily the frequency of wars parame-
ter—are very high relative to those of the two other systems.
A system will be considered stable when the values of the four param-
eters—the number, frequency, duration, and lethality of wars involving
the polar powers constituting the system, primarily the frequency of wars
parameter—are very low relative to those of the two other systems.