The Cartesian Project: A Framework for Unifying Knowledge
Introduction
Despite having been a student at one of the most celebrated schools in Europe, Descartes recognizes the profound uncertainty that marked the end of his studies. “I found myself lost among so many mistakes and doubts, which I found trying to teach me that there was managed to have discovered another benefit to growing my ignorance.” He held a critical view of the philosophy he had learned, precisely because, as he writes in Discourse on Method, “It would be hard to imagine anything so strange and incredible as to what has not been said by some philosopher,” and continues, “Although philosophy has been cultivated by the finest minds that ever lived, it cannot boast of anything that is not discussed and therefore is not doubtful.“
Thus, the philosopher, now aware of the pressure of new scientific discoveries (Galileo, Kepler), deems it necessary and urgent to design a philosophy that justifies the general confidence in reason. This philosophy must be metaphysically founded, capable of directing the search for truth, and possess a universal and fruitful method.
The importance of the metaphysical foundation is essential because the entire edifice of knowledge he aims to build will rest upon it. The French philosopher does not separate philosophy from science because his project is the knowledge of the totality of reality. As the priest Claudio Picot writes, “So, all philosophy is like a tree whose roots are metaphysics, the trunk is physics, and the branches coming out of this trunk are all the other sciences, which are reduced three main areas: medicine, mechanics and morals.“
Brief Summary
- What is known as the “Cartesian project” is the foundation and unification of knowledge.
- This involves considering all sciences as an organic whole with a unitary method drawn from mathematics.
- While employing this method, a healthy prudence suggests we act in accordance with a provisional morality.
- Believing in the soundness of the mathematical method of deducing new truths from evident axioms, Descartes decides to apply the same to all knowledge.
- This means subjecting everything to doubt (methodological doubt) until a first truth is found.
- The cogito, Descartes argues, is the first truth truly immune to doubt because it presents itself to our consciousness clearly and distinctly (evidence).
- Once this first truth is found, it is used as a criterion of certainty, as the prototype of all future truth: everything presented to our mind with the same evidence will be considered true.
- Thanks to the theory of divine truth, God will become the guarantor of this criterion. But first, His existence must be proven.
- Finally, the existence of extended substance must be demonstrated.
The Cartesian Project and Its Assumptions
The Cartesian project aims to unify all sciences into one. This is possible for Descartes because of the following assumptions:
First Assumption: All Sciences are but Wisdom
Human wisdom is the sum of all sciences, which Descartes conceives as an organic system. This system is like a tree whose roots are metaphysics, the trunk is physics or natural philosophy, and the branches are other sciences, especially medicine, mechanics, and morals. This is possible because all sciences are the result of humankind’s use of reason, a power that remains the same regardless of the field of study to which it is applied.
Second Assumption: A Model for Rational Inquiry
Do we know of any discipline whose use of reason has achieved undeniable truths that we can adopt as a model? The model for the rational philosopher, Descartes believes, is mathematics. Mathematical truth is the ideal kind of scientific truth because it is certain and indubitable knowledge. However, this does not mean that philosophical questions should be discussed in quantitative and mathematical formulas, as if philosophical problems could be solved by mere calculations.
Descartes takes two key elements from mathematics:
- Certainty of Knowledge: Mathematical knowledge is certain and indubitable, causing clear agreement among those who practice it and leading to cumulative knowledge. This is precisely what Descartes desired for philosophy—a knowledge as rigorous and certain as that of mathematics.
- Deductive Method: Descartes observes that, particularly in geometry, mathematics seeks elementary propositions whose truth is evident to any attentive mind. These propositions are called axioms, and we know them to be true by a simple act of the mind called intuition. From these principles, other more complex and obscure propositions are demonstrated through deductively linked chains. These propositions are called theorems, and their truth is reached through the act of reason called deduction. Philosophy, Descartes argues, should follow this same argumentative style: starting from the intuition of absolutely clear truths, we can figure out the rest of the truths that the mind sees clearly to be true.
Third Assumption: Renouncing Sensory Deception
Just as with mathematical truth, philosophical truth is attainable only if we renounce the deceit of our senses. If we ignore the sensible and resort to the intelligible, only then can understanding reach the truth. To avoid error, we must not rely on the fluctuating testimony of the senses, nor on the imagination or inconsistent opinions. It is therefore logical, for all these reasons, to categorize Descartes as a rationalist.
“In short, awake or asleep we must not ever persuade if not for the evidence of reason. And note I say of reason, not imagination or the senses.” (Discourse on Method., 4th p.)
Fourth Assumption: Reason’s Self-Sufficiency
The rationalist believes that reason is self-sufficient as a source of knowledge. Only reason can judge truth. Reason produces knowledge of nature with its own forces, just as it does in mathematics. Science is built on certain ideas and clear principles that are innate to the intellect, possessed independently of any sensory experience. Experience merely provides the opportunity to corroborate what has already been discovered through pure rational reflection.