Aristotle's theory of a person's "function" said that

It was the requirement of the government to serve people and help them to live rightly. Great personal fulfillment is achieved when a person is given the freedom to pursue his dreams.

this means that germany had to pay the allied countries. reparations are/is essentially payment for something that they have done wrong, so after ww1, germany was forced to pay reparations so they could replenish the allied countries resources' that they had lost during the war.

with my recent question