Immanuel Kant, well known in the international relations circle as been attributed to be the father of modern morality, instigated the preconditions for the lasting perpetual peace. His ideas were highly influenced by the American independance and the vastness of European imperialism throughout the globe.

He has listed six preconditions for a perpetual peace:

`no treaty of peace shall be held to be such, which is made with the secret reservation of the material for a future war’

`no state having an independent existence, where it be small or great may be acquired by another state, through interference, exchange purchase or gift’

‘Standing Armies (miles perpetuus) Shall in Time Be Totally Abolished’

‘National Debts Shall Not Be Contracted with a View to the External Friction of States’

‘no state shall interfere by force in the constitution and government of another state’

`No state at war with another shall permit such acts of warfare as must make mutual confidence impossible in time of future peace; such as in the employment of assassins or poisoners, the violation of articles of surrender, the instigation of treason in the state against which it is making war.’

All of these principles – that one should abide by peace treaties; that the independence of sovereign states should be respected and that one should not use dirty or extreme methods in war are principles which are moral injunctions dictated by reason. But as Kant also recognised these principles can be reached by means of enlightened self-interest as well.
Enlightened self-interest tells us to abide by our promises because if we do not no-one will trust us and enter into peaceful agreements or security arrangements with us; non-interference is also a prudential maxim because if we interfere with others we will no doubt be interfered with in turn; finally, it would also seem prudent not to use inhumane means in the course of war as this invites retaliation.

All of the principles as outlined by Kant is relevant and observed today through hard international instruments and customs, excluding ‘no standing armies’. He does however, condone militiamen as a replacement to standing armies in case of any invasion from the external force. This idea is observed in Switzerland.