Four hundred years ago, on June 19, 1623, Blaise Pascal was born in Clermont-Ferrand. Mathematician, physicist, philosopher, theologian, Blaise Pascal has become a figure of the French mind, handling figures as well as words. Brilliant scientist of his time, he contributed to the influence of France and laid a number of foundations for modern science. The mathematician Cédric Villani retraces, for Le Point, the history and career of this scientist whose achievements and turn of mind still find echoes in the 21st century.
Le Point: What were Pascal’s contributions to France?
They are numerous. We can cite, in physics, his work on atmospheric pressure, whose current unit of measurement is the pascal. In mathematics, he laid down the basic rules of probability calculations, he also developed, with his contemporaries, what is now called integral calculus, and he is even credited with the invention of the symbol “S” lengthened to designate the integral summation. We can also cite the first modern induction reasoning. For all of these reasons, Pascal is still a fun-to-read and highly accessible author.
Do objects invented today still owe to the work of Pascal?
Without a doubt. Its impact in practical terms bears primarily on IT. We must consider Pascal as one of the precursors and a tutelary figure of the discipline. We often talk about Leibniz [Gottfried Wilhelm Leibniz, German philosopher and scientist, 1646-1716, editor’s note] as being the founder of computing because he worked on logic, binary notation, the first modern calculators, but Leibniz was very inspired by Pascal.
It was Pascal who invented the first machine that automatically adds numbers, the pascaline, named in his honor. Leibniz perfected this machine to make it an automatic multiplier but there is no doubt that he read Pascal and was inspired by it. Pascal’s name has also been given to many things in the computer world, such as a programming language, but also a grand prize from the Academy of Sciences, a club of digital entrepreneurs or even a business. quantum computing.
We find, in Pascal’s work, the fundamentals of Silicon Valley, with the obsession to speak directly to the public rather than only to those who know. Pascal sells a use of his pascaline so easy that a few minutes will suffice to understand how it works. We also find the obsession with design, the perfectionism of form and construction, the obsession with intellectual property.
Pascal will maneuver until obtaining the equivalent of a patent and he denounces imitators with great violence. We also find, for the first time, the idea that science and engineering will make it possible to revolutionize people’s daily lives and simplify their lives. Pascal hoped for commercial success – which he did not meet – with this calculating machine, it is an extremely innovative approach.
His philosophy also addresses very contemporary themes…
Indeed, we find in germ, in Pascal’s texts, major themes that will flourish in the twentieth century. He explores the interaction between human and machine, which is one of the characteristics of his work, at the heart of which we find ourselves with all the questions related to artificial intelligence. We also find, in Pascal’s texts, the criticism of those whom he calls the “demi-skilled”, the scholars who think themselves clever with their remarks but give bad criticism.
Pascal’s teaching has too often remained confined to his text of Thoughts and his reflections on the bet, a mixture of philosophy and theology. His work is actually much richer than that, his way of articulating together the economic, philosophical and scientific spheres is, I believe, unequaled to this day.
There is also something fascinating in his way of always feeding on contradictions and polemics. Pascal maintains that one can defend one thesis and the opposite thesis, adores marrying foreign concepts to each other. He also praises proof by the absurd as the best there is. But these paradoxes have not handicapped him, on the contrary.
Perhaps our world is full of paradoxes, concerning both human nature and the nature of the world, and it takes a mind that feeds on paradoxes to find the right angles of reflection.
Was Pascal recognized by the scientists of his time?
Yes, in particular by Fermat [Pierre de Fermat, born in the first decade of the 17th century and died in 1665, editor’s note], probably the greatest mathematician of this period, who had a high regard for Pascal, who recognized the merits of his very great originality and how much he had been able to advance science with his different way of seeing things.
When Pascal begins researching probability, no civilization anywhere else in the world has done so?
When we search, we can always find precursors, there is nothing that suddenly arises from nothingness. But Pascal writes the first text which exposes a coherent mathematical theory of probability. The problems that motivate Pascal come from the world of bettors, where he has many connections. These players had themselves a pragmatic, intuitive knowledge of probabilistic estimates, without rigorous calculation.
Pascal wanted to develop this theory to make the link between the scientific world and the world of players, but also to put into calculation what seems a priori incalculable: chance. It is very daring. Pascal is a go-between, who makes the worlds communicate with each other, while affirming, and this is again a paradox, that there is no universal knowledge, that there are partitions between the different spheres of world. He creates partitions to then take pleasure in passing them.
Nice coincidence or just intuition, modern physics has actually recognized that at the level of elementary particles, several distinct states can exist simultaneously. It is certain that Pascal would have loved quantum physics.
How today can science and spirituality communicate?
Many researchers are asking the question. This questioning of the communication between science and spirituality comes back in force at a time when, at regular intervals, we see that the scientific approach as such is not sufficient to bring progress and where there is a lot of reflection on the spirituality and its connection to religion.
Pascal probably sensed very early on that there were fundamental aspirations in humanity that had to be preserved. He considered absurd the efforts to place spirituality under the reign of reason. He considered it essential to see how science and spirituality communicate together, like two interacting spheres, while respecting their respective sovereignty.
The scientific approach as such does not normally need to be nurtured by philosophy, but Pascal showed that, in order to have fair and lasting reflections on the world, it was necessary to combine these different elements. In the text of the bet, which has been much commented on, he brings together philosophical considerations and others, much more pragmatic.
What impact did Pascal’s Jansenist philosophy have on his view of mathematics?
It is debatable even among experts and it is even debated whether he was truly a Jansenist or whether it was simply a period in his life which he then put aside. What is important is rather that Pascal was nourished by this era of theological debate and that this reinforced his virtuosity in scientific debates. His way of handling concepts that are beyond our intuition, of linking things together, of reformulating and changing points of view: we find these figures of thought as much in his philosophy and his theology as in his mathematical style.
We find, nowadays, everything that we saw at the time, but in a more polished way. In four centuries, the practice of science has been framed by rules related to publication, peer review and career evaluation. There can of course be particularly emotional cases, like the Covid-19 crisis, or research that can be at the border between science and philosophy, like certain branches of fundamental physics, artificial intelligence, multiverses.
The great public scientific contests still existed in the 19th century, but the 20th century is the century of the professionalization of science with the arrival of major national research programs, the recruitment of a large number of scientists, large institutions, the moment when science , sociologically, takes its modern form.
For sure, right-leaning personalities will also find something to love about Pascal. Firstly because he is a great Christian author, then because he gave a major influence to France. It also fixed the French language. From a political point of view, he was nothing like a revolutionary. He knows that humans have a hard time telling right from wrong but can see where the strength is. Accordingly, he considers that one should not make strong what is right, but make right what is strong.
He is for the improvement of the established order. And liberals, certainly, can be seduced by his entrepreneurial audacity. It is another paradox that a figure who was not particularly revolutionary should be adored by left-wing intellectuals and ecologists. Pascal, with his nuances and his contradictions, has a whole range of values ??and incarnations which, for sure, make him a popular figure on the left, on the right and among ecologists.