Descartes' Method for Certain Knowledge
Classified in Philosophy and ethics
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Descartes' Methodic Doubt
Descartes resolved to doubt all the beliefs he had hitherto accepted as true, subjecting them to trial so that reason might accept them again only if they proved certain.
The Search for a New Method
He recognized the need to find a new method, reflecting on the studies he pursued in his youth: Logic, Mathematics, and Algebra.
Learning from Past Studies
After thorough study of these arts and sciences, he found many imperfections, which led him to conceive of another method that would bring together the advantages of these three while being free of their defects.
Principles of the Method
This method aimed to achieve certainty by avoiding lengthy chains of reasoning. It would be based on intuitive and concrete reasoning, as error is impossible in them. There must be order, simplicity, and clarity.
The Four Rules
The rules of the method are:
Rule 1: Intuition
Not to accept anything as true unless its evidence was clear and distinct, thus avoiding precipitation and prejudice. What is clear is what cannot be doubted.
Rule 2: Analysis
To divide each difficulty into as many parts as possible or required for its solution, in order to arrive at the simple elements.
Rule 3: Synthesis
To conduct thoughts in an orderly fashion, starting with the simplest objects and those easiest to know, so as to ascend gradually to the knowledge of more complex things.
Rule 4: Enumeration
To make enumerations so complete and reviews so general that he could be sure nothing was omitted. Like a chain, each link must be perfect; just one imperfect link implies weakness in the entire chain.
Mathematics as the Ideal Model
Descartes took mathematics as a model of clear and certain knowledge and applied this method and mathematical model to the entire sphere of human knowledge. He began his research with the simplest things in mathematics, as training to accustom the mind to grasp truth.
He took the best of geometrical analysis and algebra, choosing the line as a symbol of all magnitudes in its simplicity. In short, Descartes mastered these two sciences, always beginning with the simplest things and making every truth he discovered a general rule which served at once to find others. He not only discovered solutions to problems he tackled but also determined the means and extent to which unresolved problems could be solved.
In mathematics, truth is singular, and one knows precisely what can and cannot be known about it.
Applying the Method to Philosophy
Recognizing the power of mathematics in employing reason, he decided to apply this method to the difficulties of other sciences. However, noting that all these principles are grounded in philosophy, where certainty was still lacking, he resolved to make his primary attempt there.
A Lifelong Project
He resolved to undertake this task early in his life, deciding to apply the method primarily after gaining more experience, uprooting the bad habits of his mind, and further refining the method described above.