The works in the Central Works of Philosophy volumes have been chosen because of their fundamental importance in the history of philosophy and for the development of human thought. Other works might have been chosen; however, the underlying idea is that if any works should be chosen, then these certainly should be. In the cases where the work is a philosopher's magnum opus the essay on it gives an excellent overview of the philosopher's thought.

Chapter 1 by Michelle Grier introduces Kant's Critique of Pure Reason. Few works have been more influential in philosophy. Kant's transcendental idealism attempted to set the limits of what could be known within the bounds of possible experiences (phenomena). In this way he could give grounds, contra empiricism, as to why the basic assumptions of science such as causality applied to the world, and why, contra rationalism, we should refrain from metaphysical speculation concerning things-in-themselves (noumena) – things as they are independently of how they can appear to us – where no experience could possibly settle the problems raised. We know that the world will conform to our basic conceptual categories for understanding it because those categories are the structure of any possible experience imposed by the mind as a condition for having those experiences, and the world just is the sum of possible experiences, if it is anything at all to us. He aimed also to leave a realm beyond science, beyond phenomenal experience, that would provide room for moral responsibility and faith in God.