Kant's essay in some ways resembles modern democratic peace theory. He speaks of republican states, which he defines to have representative governments, in which the legislature is separated from the executive.
The essay does not treat republican governments as sufficient by themselves to produce peace: freedom of emigration (hospitality) and a league of nations are necessary to consciously enact his six-point program.
Kant claims that republics will be at peace not only with each other, but are more pacific than other forms of government in general.