American philosopher Daniel Dennett died at the age of 82 on Friday April 19. With him, we lose not only a great thinker, but also a precious friend, because, as fierce as he may have been in his arguments and his battles, notably his defense of atheism, he was and will remain, throughout his work, an unwavering friend of humankind.

Throughout a career that began with the birth of cognitive sciences, he endeavored to show that it was possible to understand the human mind, and all its highest manifestations − intelligence, consciousness, creativity, free will −, on the basis of material explanations, from the principles of physics and biology.

In this approach, he never limited himself to the discussion between philosophers: he entered the laboratories, exchanged and collaborated with neuroscientists, psychologists, linguists, computer scientists… He made the philosophical approach to experimentalists and, reciprocally, he popularized among philosophers a reflection as close as possible to experimentation. In doing so, he has greatly contributed to the decompartmentalization of disciplines which is today the richness and vigor of cognitive sciences.

As a child, Dan Dennett must have been the type to take the radio apart down to the last piece to understand all the steps that lead from inert spare parts to the apparent “miracle” of a box that produces music and sound. word. It is a similar debunking that he employed to try to understand the link between brain and mind, with a requirement, a determination and a good humor that are contagious for some, irritating for others.

Reflection on the evolution of functions

In his book Consciousness Explained (Odile Jacob, 1993), he attacks what he calls “the illusion of the Cartesian theater”, that is to say the temptation, difficult to combat as it is intuitive, to see the brain as a machine which encodes objects from the external world in the form of neuronal activity, to then reproject them to a central entity, a homunculus which would be the seat of our consciousness. But this proposition only postpones the problem, because we must then ask ourselves what is the entity, within this homunculus, which “sees” or “hears” what is thus reprojected to it.

In a proposition that has marked brain science, Dennett reverses the reasoning: nowhere in the brain are there neurons or sets of neurons that “see”, “understand” or “want”, because, taken in isolation , they do very limited and stereotypical work. Their collective activity, however, brings out functional properties of interest to the individual, which we call “seeing”, “understanding” or “want”.

As in a radio, there is not, at the end of the chain, a single component that sings, but rather it is the physical interactions between the different components that produce the sound. Here comes the reflection on the evolution of functions, the second major guiding idea of ​​Dennett’s thought. Unlike a radio, the human brain is a biological entity; it was therefore not designed for an external purpose, but was modeled by a process of natural selection.

Dennett set about the immense task of imagining the steps which, through mechanical and natural processes, gradually led to the appearance of individuals who developed a language, and found words to describe themselves. This language, finally, opens the door to a whole new process of natural selection, which no longer concerns genes, but “memes”, that is to say units of meaning which are transmitted from one source to another. individual to another, such as the concept of “self” − the most popular concepts survive, are transmitted from generation to generation and constitute a culture.

Millions of years of evolution leading from simple self-replicating molecules to modern human societies is wonderful, possibly dangerous, Dennett tells us, but it is not a miracle, there is nothing magical or magical about it. inexplicable. Through this founding approach, Dennett profoundly shaped and enriched our conceptions of the relationship between cerebral activity and mental activity, and was a source of inspiration for numerous theories.

Discarding “dei ex machina”

Dennett has been criticized for eliminating subjectivity, free will, for wanting to deny humans their humanity by reducing them to their physical and biological determinants. Is this really the case? In Evolutionary Theory of Freedom (Odile Jacob, 2004), Dennett evokes a scene from Walt Disney’s animated film Dumbo the Elephant, in which the baby elephant manages to fly for the first time thanks to its very large ears.

As he hesitates to take off, one of his crow friends hands him a feather, assuring him that it is magical and will allow him to fly. Clutching the precious talisman in his trunk, Dumbo finally takes flight, but everyone understands that it is the beating of his very large ears that allows him to fly, and not the magic feather. Dennett imagines that another friend could tell Dumbo the truth: he is the one who flies, not the feather! Would this deny Dumbo his ability to fly? Or on the contrary reveal to him the true cause of his gift?

Like this frank companion, Dennett in no way denies the existence and importance of consciousness or free will, but seeks to return to their real foundations, putting aside the dei ex machina. Ultimately, isn’t that what truly taking consciousness, freedom and ethics seriously is about wanting to anchor them in our most assured knowledge?

Let us bet that Dan Dennett did not ascend to heaven, he who did not believe in it, but let us keep a warm place for him, where his work destined him, at the heart of our consciences.

by Claire Sergent, Jérôme Sackur, Frédérique de Vignemont, Pascal Ludwig, Matthias Michel

March 28, 1942 Born in Boston (United States, Massachusetts)

1993 Consciousness explained (Odile Jacob)

2000 Is Darwin Dangerous? (Odile Jacob)

2004 Evolutionary theory of freedom (Odile Jacob)

April 19, 2024 Died in Portland, Maine