The Latin phrase cogito ergo sum, which translates as “I think therefore I am,” is the “first principle” of René Descartes’ philosophy. In his 1637 Discourse on the Method, it was first published in French as “Je pense, donc je suis.”
The concept is an essential component of Western philosophy, claiming to lay the foundation for knowledge in the face of severe doubt.
Descartes was one of the first philosophers to reject Scholastic Aristotelianism’s orthodox belief system and embrace the power of logic, developing an innovative method of doubt (known as “Cartesian Doubt”) and believing that large problems should be approached through a series of clear, understandable questions.
He also advocated for a new concept of mind-body dualism and constructed a heliocentric model of the universe, and his contributions to philosophy and science helped transform how we see the world around us.
Descartes’ famous argument, Cogito Ergo Sum, is often interpreted in various ways, but what it actually means can be difficult to decipher.
Descartes utilizes doubt to remove ungrounded ideas in the First Meditation, sweeping away all false beliefs based on sense experiences and starting from scratch, constructing his knowledge on more firm foundations.
His method of doubt is a logical extension of his internalist account that all justifying factors must take the form of ideas; it implies that all of his thoughts and experiences are occurring in a dream, which means that his sense perceptions are not the same as his conscious awareness or even his immediate mind.
To a twentieth-century reader, this appears to cast doubt on all everlasting truths; it is also brutally circular, which is exacerbated by Descartes’ assumption of the C&D Rule before employing it to present a series of proofs of God.
In the Second Meditation, Descartes utilizes doubt as a way to study the nature of reality, beginning by doubting everything he believes to be true, including the existence of the physical universe and his own body.
Descartes continues to cast doubt on all of his beliefs in this meditation, determining what can be known with certainty and believing that only intellectual and abstract objects can be known with absolute certainty because they do not rely on the senses, which can be deceived.
He explores the concept of mind and body, and he questions sensory perception, memory, extension, mobility, and place; he also claims that bodies are not strictly seen by the senses and that their attributes can change over time, a process he refers to as “waxing.”
The Third Meditation is possibly the most important of Descartes’ six meditations on the First Philosophy, laying the framework for his proof of God’s existence and the truth of all that can be plainly and definitely viewed by natural light.
The meditation begins by categorizing ideas into three types: images, volitions, and judgments. Ideas can be innate, invented, or adventitious, which means they are the result of some kind of cause (either an omnipotent deity or a human being) introducing extrinsic material elements into the idea.
The meditation also lays forth the criteria that must be present in an idea for it to have objective reality, one of which is that the cause of an idea must have at least as much formal actuality or perfection as the thought itself.
