This thesis has as its main aim to present Peirce's project as an organic system that is able to provide a reasonable account of our complex experience of freedom. For this reason, in the first chapter I will maintain that there are three conditions of possibility for human freedom that can be established according to an attentive reading of Aristotle's works, namely, the contingency of the world, the existence of a being who can take advantage of the world's contingency, and the capacity of a person to decide his or her own idea of Happiness or final good in a human community. These conditions can be tracked, consolidated, and improved through Peirce's philosophy. It can be tracked, first of all, in their common perspective regarding the world's element of contingency and openness to growth. Second, both philosophers think that human beings have the power to decide and actively participate in the world through experience and habit. Finally, both grant an important role to community in their philosophies in order to give sense to persons' actions. After establishing this background, I will focus primarily on the detailed presentation of the first condition of possibility for freedom, that is, in Peirce's idea of God as a metaphysical condition for freedom. In the second chapter, I will explore the historical development of Peirce's cosmology, in order to show that Peirce's idea of God is not the product of a stubborn religious prejudice but a genuine achievement of his philosophy that harmonizes with his general project of an evolutionary philosophy open to critique and working hand in hand with science. Finally, in the third chapter, I will try to clarify further Peirce's idea of God in dealing with some misconceptions generated by standard religious notions of God and by the philosophical conception of the Absolute. Thus, I hope to present Peirce's idea of God as a middle ground between these two approaches. I will argue that, on the one hand, he wanted to propose an idea of God that is open to scientific critique, as is the conception of the philosophical Absolute. On the other hand, he defended an idea of God that has bearing upon our conduct of life and, therefore, is sentimental and approachable as is the idea of God proposed at least by Christian religion. As a result, Peirce's God works as a condition of possibility for freedom insofar as he is the living idea of a developmental telos open to growth. That is, Peirce provided an idea of a cosmos that shares with us the general features of being reasonable and free.