I Think Therefore I Am: Cogito Ergo Sum Explained

Saga Foss

May 4, 2023

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The Latin cogito, ergo sum, usually translated into English as “I think therefore I am,” is the “first principle” of René Descartes’ philosophy. The principle is a fundamental element of Western philosophy. It purports to provide a certain foundation for knowledge in the face of radical doubt.

The Cogito Ergo Sum

Descartes was one of the first philosophers to abandon the orthodox belief system of Scholastic Aristotelianism and embrace the power of logic. He developed an innovative method of doubt (known as ‘Cartesian Doubt’) and believed that one should approach large problems through a series of clear, understandable questions.

He also pushed for a new understanding of mind-body dualism and established a heliocentric model for the universe. His work on philosophy and science helped revolutionize the way we view the world around us.

The First Meditation

In the First Meditation, Descartes uses doubt to overcome ungrounded beliefs. He is able to sweep away all the false beliefs that he has based on sense experiences and start from scratch, building his knowledge on more certain foundations.

His method of doubt is a logical extension of his internalist account that all justifying factors must take the form of ideas. His method of doubt implies that all his thoughts and experiences are occurring in a dream, which is to say that his sense perceptions are not the same as his conscious awareness or even his immediate mind.

To a twentieth-century reader, this seems to cast doubt on all eternal truths. It is viciously circular, too, in a way that is aggravated by the fact that Descartes assumes the C&D Rule before using it to demonstrate a series of proofs of God.

The Second Meditation

In the Second Meditation, Descartes uses doubt as a method to explore the nature of reality. He begins by doubting everything he believes to be true, including the existence of the physical world and his own body.

In this meditation, Descartes continues to cast doubt on all of his beliefs and determine what can be known with certainty. He considers the concept of mind and body, and he casts doubt on sensory perception as well as memory, extension, movement, and place. The Third Meditation

The Third Meditation is perhaps the most important of Descartes’ six meditations on the First Philosophy. It lays the groundwork for his proof that God exists and that everything that can be clearly and distinctly perceived by natural light is true.

The meditation begins by classifying ideas into different kinds: images, volitions, and judgments. The ideas can be either innate, invented, or adventitious, meaning that they are the result of some kind of cause (either an omnipotent deity or a human being) adding extrinsic material elements to the idea.

The meditation also lays out the principles that must be present in an idea in order for it to have objective reality. Among these principles is the fact that the cause of an idea must have at least as much formal reality or perfection as the idea itself has objective reality.