Source: Originally in La Correspondance internationale, no. 23, 1937. In Ecrits 1: La Philosophie et les Mythes, edited by Jacques Debouzy, Éditions Sociales, Paris, 1969;
Translated : for marxists.org by Mitch Abidor
In the month of June of this year , exactly three hundred years ago, The Discourse on the Method of Rightly Conducting the Reason and Seeking Truth in the Sciences by Rene Descartes came out for the first time, without an author’s name.
The French Communist Party has made a particular effort to see to it that the celebration of this anniversary goes beyond the framework of an academic commemoration.
In the name of the Communist parliamentary group, our comrades Cogniot and Berlioz have registered a proposition inviting the government to take all the needed steps to organize the “National Celebration of the Tri-centennial of the Discourse on Method of René Descartes.” The Party press is making known to the working class and the popular masses of France the work of Descartes.
Our Party has thus taken the lead in the celebrations of the tri-centennial of the Discourse.
Descartes is one of the greatest French thinkers, and one of the greatest geniuses that France has given to humanity.
His works, whose universality is one of its most characteristic traits, embrace the principal branches of knowledge, and in each of them Descartes was a great innovator.
He was a metaphysician, but in the manner of the great metaphysicians of the 17th century.
“Metaphysics in the 17th century (c.f., Descartes, of Liebniz, and others) still contained a positive secular element. It made discoveries in mathematics, physics, and other exact sciences which seemed to come within its scope.” 
In fact, Descartes was one of the creators of modern mathematics.
In physics Descartes is the first to have understood the entire extent and to have applied in a consistent manner the mathematical-experimental model, in this way taking a giant step in the path opened by Francis Bacon and Galileo, himself opening the way for Newton.
In the biological sciences as well, Descartes is the first to seek in a systematic manner to explain organic phenomena by the positive data of science.
Brilliant innovator in philosophy, in the principal branches of science Descartes was also, like Francis Bacon, an innovator in technique in the sense that he proclaimed with perfect clarity that true science was the condition for an effective technique. With this as his starting point, he occupied himself particularly in the renewal of medicine on a scientific basis.
Thanks to the genius of Descartes French thought in the 17th century sparkled with an incomparable shine.
But the honors rendered to Descartes in the current circumstances take on a new meaning, which the Discourse on Method, published in Holland anonymously for fear of persecution by the Church, is the symbol par excellence.
Descartes not only made brilliant scientific discoveries: he undertook the radical reform of the entire scientific edifice. He understood that modern science was the negation of the bookish and ineffective science left by the Middle Ages, and he expressed this negation in a decisive and consistent manner, rejecting en bloc Scholasticism, and Aristotle’s authority, with which the former associated itself. He thus completed the great critical work of the Renaissance.
This negation was so conscious in Descartes that he several times expressed the idea that between his philosophy and Scholasticism there is such an opposition that if one is true, then the other is necessarily false. Mechanics, which Descartes wanted to construct without the notion of force, since the latter was of Aristotelian origin, shows to what extent, in this negation of Scholasticism, Descartes wanted to be consistent, thus attracting the celebrated criticisms of Leibniz and later Voltaire, determining the Cartesians to later fight against the Newtonian notion of universal gravitation.
But what constitutes the most universal value of the work of Descartes, the source of his most decisive influence and, with mathematical physics, the most living aspect of his work, is that Descartes did not limit the negation of Scholasticism and the authority of tradition to the problems of particular sciences. He denied the authority of tradition and Scholasticism as a whole, proclaiming in their face the rights of critical spirit and Reason, seeking to derive from the most highly evolved sciences, like mathematics, a universal method.
In this way Descartes opens the way not only to other great metaphysicians who were champions of free thought, like Spinoza, but also to the French Encyclopedists. Descartes is the brilliant champion of modern thought, who sees in the positive sciences the only road that can lead man to true knowledge and, through true knowledge, to the conscious mastery of natural and social forces. D’Alembert wrote of him:
“Descartes dared, at least, to show good spirits how to shake off the yoke of the Scholastics, of opinion, of authority, in a word, of prejudices and barbarism. And by this revolt, the fruits of which we now harvest, he rendered a service to philosophy more essential perhaps than all those it owes to his illustrious successors.” 
The philosophical and scientific progress to which Descartes opened the way, as well as society’s evolution, have brought our knowledge and method to a superior level. The Cartesian dualism of extension and of thought, that is to say mind and matter, was already surpassed by Spinoza, who was surpassed in turn by Leibniz, and by French materialism of the 18th century.
“Mechanical French materialism,” Marx wrote, “adopted Descartes’ physics in opposition to his metaphysics. His followers were by profession anti-metaphysicians, i.e, physicists.” 
Mechanical materialism in its turn was surpassed by dialectical materialism.
But these diverse progresses fed off of Descartes and successively assimilated, in a more or less perfected form, what there is that is alive in the work of Descartes.
The Encyclopedists fought Descartes’ metaphysics. But, D’Alembert said:
“the arms that we use to fight him don’t belong to him any the less, just because we turn them against him.” 
Critical spirit, the right to free examination, Reason enlightened by the most modern science as a method of thought, all these aspects of Cartesianism have become an integral part of all of human civilization.
Today fascism attempts not only to prevent society from continuing its progress, which has taken it beyond Descartes; it wants to take things back to the period before him, to material and moral barbarism, to the bloody dictatorship of capitalist oligarchies in practice, to obscurantism and to the authoritarianism in theory. Just as they are in struggle against the great political traditions of the French Revolution, Mussolinian and Hitlerite fascism are in open struggle with all that is living in Cartesianism.
The Discourse on Method served as a preface to three scientific treatises in which Descartes demonstrates the effectiveness of his method in physics and mathematics. The Discourse itself announces the universality of the method. Published four years after the condemnation of Galileo, it was written in French and did not address itself only to the “learned” but above all to “opinion.” It begins with these words: “Good sense is of all things in the world the most equally distributed.”
It is, from the first words, the negation of Scholasticism and the method which takes authority as the source of belief. The Discourse is a manifesto of modern thought with which Descartes engages combat.
In the celebration of the tri-centennial of the Discourse France and humanity affirm their will to resolutely defend reason against obscurantism, civilization against fascist barbarism.
Reaction set itself to methodically deform Descartes’ figure. It wanted to retain of him only spiritualist metaphysics. While extolling “the genius of Descartes” it made an effort to empty him of his progressive content.
But as Marx demonstrated, Descartes is one of the sources of French materialism of the 18th century.
This Cartesian materialism is at the origin of the progress of French science. In inviting the popular masses of France to celebrate the tri-centennial of the Discourse, our Party is putting back in place historical truth. In the face of fascism, which wants to exterminate even his memory, in the face of reaction that falsifies his image, it makes known the real figure of Descartes, hero of the struggle for free thought, brilliant ancestor of the French materialists.
If the materialism that comes from Descartes was one of the tendencies of French materialism, the other was the one that is derived from Locke. Marx demonstrated that that second tendency directly meets that of socialism: “the two tendencies,” he adds, “intersect in the course of development.” 
Dialectical materialism is, as Lenin demonstrated, the modern form of materialism.
It was able to go beyond the mechanistic character that was characteristic of the materialism of the 18th century, thanks to the progress in the natural sciences in which the works and influence of Descartes were decisive.
In the very measure to which dialectical materialism is the heir of the materialism of the 18th century, of which the materialism of Cartesian origin is one of the constitutive elements, there becomes evident yet again that evolution that reveals the profound ties of Marxism and French thought, and shows just how deep the roots of Communism are in French soil.
Marx and Engels, as well as Lenin, considered Descartes, like Spinoza and Leibniz, not only an advanced thinker, but even a dialectical thinker.
Descartes only reaches the limits imposed on him by the scientific knowledge of his era in surpassing them. He has a clear consciousness that the ancient logic of Aristotle — the expression of the method that Hegel will call metaphysical — is out of date and that it is another “logic” that is at work in mathematics, and that must be put to work in physics and the other sciences if we want them to reach the truth. The Cartesian opposition of modern mathematics to the logic of Aristotle, his idea of a universal method that extracted from what there is that is most general in mathematics, is already a step in the development which, via Kant, will lead to the clear consciousness of the dialectic in Hegel.
To this must be added the Cartesian conception of matter, which also announces, like the Monads of Leibniz, the evolution that will lead physics beyond the mechanical atom.
Descartes did not and could not go beyond mechanism. But he reached its outer limits and on many points went beyond mechanical materialism.
This underlines — like the role of Descartes as champion of modern thought — up to what point it is inexact and even anti-dialectical to make of him, as was done by the followers of Deborin, the philosopher in whom “the intelligence of the bourgeoisie is incarnated.”
To say this is to forget those “cycles of philosophy” of which Lenin spoke. It is to forget what is alive in Cartesianism.
The immortal elements of Cartesianism live in science which, by an incessant comparison of thought with reality, renders this knowledge more accurate every day; in the technique that owes its effectiveness to the truth of science.
They live in the work of Marx and Engels, of Lenin and Stalin who created and developed this true social science that is the condition of effective social action in making socialism pass from utopia to science, from dream to reality.
They live in the attachment of civilized men to Reason and Freedom.
They live in the political intelligence of the popular masses, who understand that the road to unity is that of victory over the enemy and of their liberation.
1. Marx, The Holy Family (ch VI)
2. D’Alembert, Discours préliminaire de l’Encyclopédie (IIme partie)
3. Marx, The Holy Family (ch VI)
4. D’Alembert, Discours préliminaire de l’Encyclopédie (IIme partie)
5. Marx, The Holy Family (ch VI)