Full Idea
It must remain possible, even in wartime, to have some sort of trust in the attitude of the enemy, otherwise peace could not be concluded and the hostilities would turn into a war of extermination.
Gist of Idea
Some trust in the enemy is needed during wartime, or peace would be impossible
Source
Immanuel Kant (Perpetual Peace [1795], 1.6)
Book Reference
Kant,Immanuel: 'Political Writings', ed/tr. Reiss,Hans [CUP 1996], p.96
A Reaction
Consider the 'unconditional surrender' approach to the Nazis in 1944, and the peace of May 1945, made with very different Germans. How do you make peace with an enemy you cannot trust?