(Copyright © 2000 Piero Scaruffi | Legal restrictions - Termini d'uso )
The American philosopher Daniel Dennett offers a personal view of Darwin's
contribution to Science.
Darwin's "dangerous idea" is that design can emerge spontaneously via an algorithmic process, since evolution by natural selection can be viewed as an algorithmic process.
A mindless and mechanical (and relatively simple) process is responsible for creating the complex systems of life. Design is created at each run of the algorithm and conserved as the starting point for the next run. Complex design such as exhibited in living systems is therefore the product of a process of "accumulation of design" carried out over time.
Dennett emphasizes that what appears as a very intelligent process is in reality made of many tiny stupid steps (he proposed a similar explanation for the intelligence of the human mind).
Dennett defends James Mark Baldwin's effect, originally proposed in 1896: that species capable of "reinforced learning" evolve faster. Unlike Lamarck, who thought organisms can pass on to their offsprings acquired characteristics, Baldwin thought that organisms can pass on their capacity to acquire certain characteristics.
The actual genomes that have ever existed are obviously just a tiny percentage of all the genomes that could possibly exist. Biological possibility can be reduced to a search (the "tree of life") in the space of all possible genomes (the "design" space). An organism is more or less biologically possible if the corresponding genome can be more or less easily accessed from one of the existing genomes. There may be local and universal constraints (biological laws) that limit the possible routes, just like there are physical laws that limit which objects can exist. For example, laws of form may constrain the relation between genotype and phenotype.
Similar considerations apply to human artifacts, from books to religions, from languages to Dawkins' memes. They are also indirectly artifacts of the same process that created living organisms. Therefore one can conceive of a unified design space that is navigated by both biological and human creativities.
Dennett discusses how life can have created itself. Self-replicators are too complex to have occurred by coincidence. He resorts to hypotheses advanced by Cairns-Smith and Eigen.
Dennett thinks that intelligent behavior, far from being a recent human exclusive, may have emerged very early in the course of evolution, at least in the form of the ability to perform purposeful actions in complex macromolecules. In his opinion, intelligent (as in "purposeful") behavior at the macromolecular level does not require consciousness and predates multicellular organisms.
Dennett emphasizes that the code reader is as important as the code: there are infinite ways that the instructions contained in the DNA could be implemented, and the "decoder" determines which one will actually be chosen. The message is ambigous and it can be disambiguated only by the specific decoder that was meant to decode it. From this observation Dennett concludes that the code and the decoder must have evolved together. In general, Dennett argues that "any functioning structure carries information about the environment in which its function works".
Biology is just another form of engineering.
Dennett strenously defends "adaptionism" against Gould's and Lewontin's critique (a famous 1979 paper) and argues that it must form the core of evolutionary biology. He wildly misrepresents their theories, though.
The human species is unique in that it relies on cultural transmission of information, and such process is carried out by Dawkins' memes, the units of cultural evolution. The mind was created when the brain was invaded by memes: memes have created the mind, not the other way around. Consciousness is therefore a collection of memes that is implemented in the brain as a sort of software in a machine that evolved in nature. Dennett in practice denies the existence of truly conscious states. Meaning itself is an emergent product of the meaningless algorithm that carries out evolution.
Dennett defends Artificial Intelligence from Penrose's critique (based on Godel's incompleteness theorem). Artificial Intelligence actually fits very well in this scenario of algorithmic (physical and mental) evolution.