Daniel C. Dennett, Widely Read and Fiercely Debated Philosopher, Dies at 82

Daniel Dennett in about 2004. “There’s simply no polite way to tell people they’ve dedicated their lives to an illusion,” he said of religion.

Daniel C. Dennett, one of the most widely read and debated American philosophers, whose prolific works explored consciousness, free will, religion and evolutionary biology, died on Friday in Portland, Maine. He was 82.

His death, at Maine Medical Center, was caused by complications of interstitial lung disease, his wife, Susan Bell Dennett, said. He lived in Cape Elizabeth, Maine.

Mr. Dennett combined a wide range of knowledge with an easy, often playful writing style to reach a lay public, avoiding the impenetrable concepts and turgid prose of many other contemporary philosophers. Beyond his more than 20 books and scores of essays, his writings even made their way into the theater and onto the concert stage.

But Mr. Dennett, who never shirked controversy, often crossed swords with other famed scholars and thinkers.

An outspoken atheist, he at times seemed to denigrate religion. “There’s simply no polite way to tell people they’ve dedicated their lives to an illusion,” he said in a 2013 interview with The New York Times.

Mr. Dennett on the Charles River in Boston in 2013. Never shirking controversy, he often crossed swords with other famed scholars and thinkers.

According to Mr. Dennett, the human mind is no more than a brain operating as a series of algorithmic functions, akin to a computer. To believe otherwise is “profoundly naïve and anti-scientific,” he told The Times.

For Mr. Dennett, random chance played a greater role in decision-making than did motives, passions, reasoning, character or values. Free will is a fantasy, but a necessary one to gain people’s acceptance of rules that govern society, he said.

Mr. Dennett irked some scientists by asserting that natural selection alone determined evolution. He was especially disdainful of the eminent paleontologist Stephen Jay Gould, whose ideas on other factors of evolution were summarily dismissed by Mr. Dennett as “goulding.”

Not surprisingly, Mr. Dennett’s writings could elicit strong criticism as well — to which he sometimes reacted with fury.

Daniel Clement Dennett III was born on March 28, 1942, in Boston, the son of Daniel Clement Dennett Jr. and Ruth Marjorie (Leck) Dennett. His sister, Charlotte Dennett, was a lawyer and journalist.

Mr. Dennett first came to wide attention with his first book, published in 1981.

Mr. Dennett spent part of his childhood in Beirut, Lebanon, where his father was a covert intelligence agent posing as a cultural attaché in the United States Embassy, while his mother taught English at the American Community School.

Mr. Dennett in 2005 in his office at Tufts University, where he was a longtime professor and director of its Center for Cognitive Studies.

He graduated from Harvard University in 1963 and two years later earned a Ph.D. in philosophy from Oxford University. His dissertation began a lifelong quest to use empirical research as the basis of a philosophy of the mind.

Mr. Dennett taught philosophy at the University of California, Irvine, from 1965 to 1971. He then spent almost his entire career on the faculty of Tufts University, where he was director of its Center for Cognitive Studies and most recently an emeritus professor.

His first book to attract widespread scholarly notice was “Brainstorms: Philosophical Essays on Mind and Psychology,” published in 1978.

In it, Mr. Dennett asserted that multiple decisions resulted in a moral choice and that these prior, random deliberations contributed more to the way an individual acted than did the ultimate moral decision itself. Or, as he explained:

“I am faced with an important decision to make, and after a certain amount of deliberation, I say to myself: ‘That’s enough. I’ve considered this matter enough and now I’m going to act,’ in the full knowledge that I could have considered further, in the full knowledge that the eventualities may prove that I decided in error, but with the acceptance of responsibility in any case.”

Mr. Dennett’s 2013 book, written with a colleague, was based on interviews with clerics of various denominations who were secret atheists.

Some leading libertarians criticized Mr. Dennett’s model as undermining the concept of free will: If random decisions determine ultimate choice, they argued, then individuals aren’t liable for their actions.

Mr. Dennett responded that free will — like consciousness — was based on the outdated notion that the mind should be considered separate from the physical brain. Still, he asserted, free will was a necessary illusion to maintain a stable, functioning society.

“We couldn’t live the way we do without it,” he wrote in his 2017 book, “From Bacteria to Bach and Back: The Evolution of Minds.” “If — because free will is an illusion — no one is ever responsible for what they do, should we abolish yellow and red cards in soccer, the penalty box in ice hockey and all the other penalty systems in sports?”

Already with the 1991 publication of his book, “Consciousness Explained,” Mr. Dennett had expounded his belief that consciousness could be explained only by an understanding of the physiology of the brain, which he viewed as a kind of supercomputer.

“All varieties of perception — indeed all varieties of thought or mental activity — are accomplished in the brain by parallel, multitrack processes of interpretation and elaboration of sensory inputs,” he wrote. “Information entering the nervous system is under continuous ‘editorial revision.’”

By the 1990s, Mr. Dennett had increasingly sought to explain the development of the brain — and illusions of a separate consciousness and free will — in terms of the evolution of human beings from other animal life.

He believed that natural selection was the overwhelming factor in this evolution. And he insisted that physical and behavioral traits of organisms evolved primarily through their beneficial effects on survival or reproduction, thus enhancing an organism’s fitness in its environment.

Critics, like Mr. Gould, cautioned that while natural selection was important, evolution would also have to be explained by random genetic mutations that were neutral or even somewhat damaging to organisms, but that had become fixed in a population. In Mr. Gould’s view, evolution is marked by long periods of little or no change punctuated by short, rapid bursts of significant change, while Mr. Dennett defended a more gradualist view.

When his 2006 best seller was harshly criticized in The New York Times Book Review by Leon Wieseltier, Mr. Dennett answered with an angry rebuttal.

Underlying the increasingly acrimonious debate between the scholars was a natural friction in the scientific and philosophical communities over which side merited more credibility on the subject of evolution.

Mr. Dennett also plunged into controversy with his strident views on atheism. He and a colleague, Linda LaScola, researched and published a book in 2013, “Caught in the Pulpit: Leaving Belief Behind,” based on interviews with clerics of various denominations who were secret atheists. They defended their decision to continue preaching because it provided comfort and needed ritual to their congregations.

Interviews with clergy from the book became the basis of a play by Marin Gazzaniga, “The Unbelieving,” which was staged Off Broadway in 2022.

Eight years earlier, Mr. Dennett’s views on evolutionary biology and religion were the subject of “Mind Out of Matter,” a 75-minute-long musical composition by Scott Johnson performed in a seven-part concert at a theater in Montclair, N.J. The composer used recordings from Mr. Dennett’s lectures and interviews.

Mr. Dennett’s fame and following extended to both sides of the Atlantic. As he grew older, he was accompanied by his wife on his lecture tours abroad. In addition to his wife, his survivors include a daughter, Andrea Dennett Wardwell; a son, Peter; two sisters, Cynthia Yee and Charlotte Dennett; and six grandchildren.

While Mr. Dennett never held back in contradicting the views of other scholars, he bristled at harsh comments about his own work. This was especially the case when Leon Wieseltier, a well-known writer on politics, religion and culture, strongly criticized Mr. Dennett’s 2006 best seller, “Breaking the Spell: Religion as a Natural Phenomenon,” in The New York Times Book Review.

Contending that Mr. Dennett was intolerant of people who didn’t share his basic belief that science could explain all human conditions, Mr. Wieseltier concluded: “Dennett is the sort of rationalist who gives reason a bad name.”

In a lengthy, angry rebuttal, Mr. Dennett denounced Mr. Wieseltier for “flagrant falsehoods” that demonstrated a “visceral repugnance that fairly haunts Wieseltier’s railing (without arguments) against my arguments.”

An earlier, more positive appraisal of another of his best sellers, “Kinds of Minds: Toward an Understanding of Consciousness” (1996), that ran in New Scientist magazine might have come closest to explaining Mr. Dennett’s enduring appeal.

While he admitted that many of the questions he raises in his work “cannot yet be answered,” wrote the reviewer, Mr. Dennett “argues that putting the right questions is a crucial step forward.”

Kellina Moore contributed reporting.