I Am a Strange Loop , Douglas Hofstadter , Basic Books, New York, 2007. $26.95 (412 pp.). ISBN 978-0-465-03078-1
Douglas Hofstadter, the son of physics Nobel laureate Robert Hofstadter and once a solid-state physicist himself, became instantly famous with his first book Gödel, Escher, Bach: An Eternal Golden Braid (Basic Books, 1979). In it, Hofstadter, now a professor of cognitive science and computer science at Indiana University, Bloomington, exhibits a veritable obsession with the theme of self-reference. That obsession culminated in his fascination with the notion of a “strange loop,” a concept he found as a unifying theme in the work of his three protagonists: mathematician Kurt Gödel, artist Maurits C. Escher, and composer Johann Sebastian Bach. Beyond the originality of its theme, Gödel, Escher, Bach has become a classic of popular science because of Hofstadter's inimitable personal style: He explains difficult ideas with a mix of dialogue, autobiography, jokes, asides, and endless analogies and metaphors.
In I Am a Strange Loop, the dialogues have largely disappeared, but the book is still vintage Hofstadter. The fundamental message, already implicit but mostly overlooked in his 1979 book, according to Hofstadter, is the following: First, the notion of “I,” and the associated phenomena of consciousness, thinking, and the soul that Hofstadter broadly identifies, arises because of a “strange loop” inside the brain. Second, that notion turns out to be an illusion, somewhat comparable to the marble one imagines feeling between a large stack of envelopes pressed together.
By definition, a strange loop is a “level-crossing feedback loop” (page 102). What that description means is best illustrated by the example that has motivated Hofstadter since his teenage years. A large part of known mathematics, particularly number theory, can be formalized using the logical system (PM) of the Principia Mathematica, published from 1910 to 1913 by Bertrand Russell and Alfred North Whitehead. Now, the crux is that number theory by itself is sufficiently rich to encode logical reasoning, as was famously shown by Gödel in 1931. The reinterpretation of certain number-theoretic statements as logical propositions is the level-crossing called for in the definition of a strange loop. In particular, PM can be encoded within number theory, so that PM is able to reflect on itself. That concept is the feedback in the strange loop at hand.
In the strange loop of the brain that gives rise to consciousness, the role of the lowest level, analogous to PM in the mathematical example, is played by the microstructure of the brain, whereas the highest level, which would be comparable to Gödel's reinterpretation mentioned above, consists of the internal symbols representing coarse-grained reality. In vivid imagery, Hofstadter describes such high-level brain activity as a dance of symbols. According to him, the essential feature of humans, as opposed to animals, is that this representational system is universal in the sense that any pattern can be simulated by the brain, including the “dance of symbols” itself. He sees a perfect analogy with Gödel's strange loop. However, that mathematical loop closes because the highest-level formulation reflects on the lowest level; but in the human brain, the highest level reflects on itself. Ironically, in scientific papers on neurons, the highest level, the dance of symbols does reflect on the lower one, the neuron itself—but such papers neither explain nor give rise to consciousness.
Hofstadter continues his analysis by claiming that the “I” conceived as a strange loop is actually a “hallucination hallucinated by a hallucination” (page 293). His claim hinges on the fact that the dance of symbols, and hence its self-reference, is a collective effect (philosophically an epiphenomenon, like temperature) that evaporates down at the neuronal level. In a similar vein, the high-level world of classical physics could be said to be a mirage created by the underlying low-level world of quantum physics. But it is hard to see what one gains by regarding epiphenomena as illusory. In any case, with that stance Hofstadter especially challenges Cartesian and modern dualism, and he insists on a monistic, purely physical description of consciousness.
The genre of the book is philosophy of mind. There is not a single reference to a serious laboratory experiment, and Hofstadter even claims that the physical structure of the brain is as irrelevant in the explanation of consciousness as the chemical composition of molecules in the air would be to the sensation of music. He thus makes no effort whatsoever to show how the brain is able to sustain his strange loop; he even blames neurobiologists for looking for the “I” at the wrong level.
Hofstadter's approach seems to turn vice into virtue. I regard the purely philosophical nature of the book, which is entirely based on analogies and metaphors, as a serious weakness. Also, apart from a sneer here and there to his intellectual antagonists and occasional praise of kindred points of view from other scholars, the author makes almost no attempt to relate the arguments to the pertinent literature. Admittedly, although Roger Penrose's book about consciousness, Shadows of the Mind (Vintage, 1995), also heavily relies on Gödel's work, it hardly overlaps with I Am a Strange Loop. But much more could have been said in Hofstadter's book in terms of relating his own ideas to others involved in mainstream philosophy of mind. Nonetheless, I Am a Strange Loop contains many profound and unique insights on the question of who we are. In addition, it is a delightful read.
