198 internautes sur 254 ont trouvé ce commentaire utile
- Publié sur Amazon.com
Daniel Dennet, like his theory of consciousness, is all about cerebral celebrity. From his origins as a philosopher in academic halls, he has become an intellectual public icon, attracting masses of curious thinkers to his speaking engagements. He writes crisply with large helpings of humor that bite just hard enough to dent the surface without offending too much. I mostly enjoy his style. It's entertaining. This book offers a group of critical thinking tools in the first part, and then a rehashing of Dennett's philosophical positions in the latter part. If you have read all of Dennett's past work, then there is little reason to read this book. As I have only read a small sample of his older work, I bought this book for a more complete picture of his thoughts.
I was jarred by his repetitive use of the so-called sorta "operator", a neologism that Dennet believes does explanatory work, but appears to function mostly as a smoke screen that hides the complexity of what he is trying to explain. To Dennett, when he places the word sorta in front of an object, action, or almost anything at all, it (the word sorta) meaningfully transforms that thing into something else. For example, there are monkeys, and then there are sorta monkeys. Sorta monkeys fall short of being monkeys in some way--they are different than monkeys--but Dennett demands that this difference, while actual, cannot be made rigorous. There is no systematic, logical dividing line between monkeys and sorta monkeys, yet somehow we all know the difference. Dennett is doing little more than appealing to a mysterious intuition (or capacity) when using sorta in front of words, and he attempts to hide this mysterian tendency by calling sorta an operator, trying to get us to confuse his fluffy sorta with the rigorously defined operators in mathematics and physics. The derivative d/dx is an operator; sorta is an expression in everyday speech that we use to create ambivalent meaning--I sorta like peanut butter ice cream, meaning, I don't really like it all that much but it's not bad but not great and I eat it sometimes. Dennett's use of sorta is sorta helpful in explaining things, but not really.
Dennett has obviously thought long about the various thought experiments he creates and criticizes, and I found his discussion about the Chinese room argument particular enlightening. Of course Dennett can be criticized for his uncritical use of metaphors as well. For instance, Dennett calls DNA a recipe for an organism. This metaphor is so common among philosophers and scientists that it is rarely questioned, but if we take Dennett's call to analyze metaphors, we find that this metaphor is weak. A recipe for making something tells the person following that recipe the precise ingredients and steps needed to create that something. My stripped-bass with homemade stuffing recipe tells me to fillet a 4-5lb bass, gather toasted wheat bread (crumbled), herbs, mushrooms, shallots, butter, wine, parmesan cheese, and to sauté these together, then layer the stuffing between the two fillets and place the stack in the oven for 45 minutes, and to occasionally marinate with the juices. It's delicious. Now, I can read DNA, and all I see are a sequence of nucleotides--it doesn't tell me to do anything. Even if I recognized the DNA strand as hippopotamus DNA, I still would not know how to make a hippopotamus by reading the DNA strand. Perhaps you say that is an unfair comparison; the full metaphor implies that DNA is a recipe to be read by other things in the cell and not intended for a person. Very well. DNA is transcribed into RNA by RNA polymerase, which produces a complementary RNA strand. DNA is not a recipe for the organism; it is a recipe, if anything, for RNA. And RNA is not a recipe for the organism, but a recipe for perhaps proteins or other cellular components. Proteins are not recipes for the organism, but rather serve particular functions within and between cells.
But suppose I could look at a DNA strand, and knew all of the proteins that are formed from that strand--would I then know the recipe for the organism? I couldn't just throw a bunch of proteins into a pot and expect it to become a living organism. DNA is not even sorta a recipe for an organism. Unlike a recipe that contains explicit instructions or directions in the form of actions--cut the fish, sauté the mushrooms, turn the oven to 400 degrees--DNA does not contain within its "code" any directions for putting an organism together. All of the action happens as a result of basic physical forces when DNA is in an appropriate environment. DNA, if anything like a recipe, is a partial list of constituents of an organism--think of the many vitamins and minerals that are necessary for the organism but must be ingested; these are not listed anywhere within DNA. We might say that DNA in a proper cellular environment is the cause of an organism. We might say that DNA can be used to identify types of organisms and individual organisms, like finger prints and foot prints. But to call DNA a recipe for the organism is a misleading metaphor.
Dennett spends a bit of the book trying to explain how the mind is created by matter, and more generally, how people are material machines like robots. The idea that humans are material machines was argued well by the French physician La Mettrie in his book L'homme Machine (Man, Machine) written in 1748, who said that the human body is a clock, a huge and complex finely designed clock. Dennett, like many today, believes a similair thing--that the mind is a computer, a huge and complex finely designed computer. Dennett explains the mind by appealing to a doctrine of cognitive gradualism--the idea that the mind can be gradually built up by considering individual neurons, then groups of neurons with varying functions, and gradually more complex functions on top of one another until we get something like the mind in all its glory. Marvin Minsky, one of the early pioneers of AI, told a similar and very readable story in his Society of the Mind, which was not mentioned by Dennett.
Dennett's materialism is not so interesting; what is interesting about Dennett is that he is a sorta materialist. He acknowledges the irreducibility of the "intentional stance", that we will always talk "as if" humans have beliefs and desires and so forth, even if we ever explain the mind physically. He thinks concepts like "the center of gravity" refer to real entities in a meaningful way that goes beyond matter at a particular location, and believes free will is an important and actual thing, even in a world ultimately made of matter in motion. I believe Dennett's sorta materialism saves his philosophy from being dogmatic and boring. He has been called a post-analytic philosopher, but I think he is more appropriately a sorta-analytic philosopher, a transition species between analytic philosophers and continental philosophers.