This thesis analyzes the beliefs of population theorist Julian L. Simon through the creation of a harm principle. It specifically analyzes his argument that we value our freedom to choose how many children we want above all other values in the context of overpopulation and environmental destruction. The developed harm principle is meant to give us a method to decide how to balance our personal freedom with our security-survival. I begin with an overview of Simon’s work, as well as an exposition of other prominent population theorists. I then propose a principle that is a utilitarian alternative to John Stuart Mill’s Harm Principle. I apply the principle to the situation wherein overpopulation causes such great environmental damage that we must choose between upholding procreative rights and our continued survival. I conclude that in most cases we will accept limitations on our procreative freedom in order to maintain our planet and ensure our security-survival.