Descartes, René. Descartes: Key Philosphical Writings. Ed. Enrique Chávez-Arvizo. Ware, Hertfordshire: Wordsworth Editions Limited, 1997. Print.
In “Principles of Philosophy,” Descartes finds room both for God and fate as well as for free will. This free will is evident through perception and understanding. Through understanding, or careful consideration of something, we can arrive at correct knowledge about the world. However, understanding comes from perception and perception can lead us astray, to err, to misunderstanding. We can perceive (and therefore err) infinitely, but can only understand finitely. Furthermore, it is in this ability to think and to err that we maintain an agency outside of God. God is never wrong, says Descartes, and does not deceive humans, but instead gives them the capacity to think (and therefore to be sure of their own existence) and to, of their own misunderstandings and misperceptions, to arrive at incorrect information just as to correct information. The ability to think and to rationalize, Descartes also argues, gives us accountability. Our will is infinite and that will allows us to consider actions before we make them – if we make the wrong choice voluntarily via that will, we are accountable for it.