Christopher Cherniak

Christopher Cherniak is an emeritus professor of the Philosophy Department at the University of Maryland.[1] Some of his research concerns more realistic, bounded-resource models of rationality,[2] and optimal-wiring models of brain structure.

Minimal Rationality, is a book on rationality written from a philosophical and computational perspective, which tries to find middle ground between an excessive optimistic theory of belief and mere behavioristic account of belief. The first would consider something a belief only if the agent believes all its consequences (epistemic closure), the second would only take as belief a proposition if the agent asserted his belief in it. Cherniak tries to show that logical omniscience (as proposed by Hintikka and others) is untenable as a theory of belief, and at the same time as a normative theory of rationality. This is mainly due to intractable computational complexity. An agent deciding to undertake an inference that would take longer than the heat death of the Universe would be rational by purely logical standards. Instead, Cherniak proposes a minimal rationality model, where the agent only needs to make some of the appropriate inferences to count as rational. A rational agent also needs heuristics to choose which logical inferences he will choose to make. Finally, the book includes the social aspects of rationality, such as Gricean maxims, in the light of the minimal rationality theory.

On his work on brain structure, Cherniak conjectures that, at least in some cases, animals have "the best of all possible brains.." He reports that the nervous system of the nematode Caenorhabditis elegans, with 302 neurons, is organized to "Save wire" with respect to placement of some nervous system components.[3] Neural components include entities at different structural levels: brain, ganglia, neurons, arbors. Using combinatorial network optimization theory, Cherniak finds the "brain" and its ganglia are positioned optimally within the worm's body to minimize total wirelength of the nervous system. The significance of this result includes the fact that in general solving such component placement optimization problems has exponential cost—e.g., there are an inscrutible number of possible arrangements for the 302 neurons.

Cherniak also reports similar optimal wiring findings for positioning of areas of mammalian cerebral cortex.[4] In some cases, cortex interconnection minimization appears either perfect, or as good as can be detected by current methods—a predictive success story.

Cherniak makes corresponding claims about the structure of some axonal and dendritic arbors—both are optimized with respect to volume.[5] Cherniak proposes fluid dynamic mechanisms for these observed minimal tree structures, which are isomorphic to the patterns of river drainage systems. All these instances of optimized neuroanatomy include candidates for some of the most complex biological structures known to be derivable "for free, directly from physics".—In this way, "Physics suffices". Nativists are interested in such claims.[6]

Cherniak's other work includes some fiction, including The Riddle of the Universe and Its Solution.[7]

On February 20, 2009, Saisho Gorisei, the Japanese version of Minimal Rationality, was published in Tokyo, Japan.[8]

References

  1. ↑ List of People in the Department of Philosophy, University of Maryland
  2. ↑ Cherniak, Christopher (1986). Minimal rationality. MIT Press. ISBN 0-262-03122-1.
  3. ↑ Cherniak, C. (1995). "Neural component placement". Trends in Neurosciences 18 (12): 522–527. doi:10.1016/0166-2236(95)98373-7. PMID 8638292.
  4. ↑ Cherniak, C.; Mokhtarzada, Z.; Rodriguez-Esteban, R.; Changizi, B. (2004). "Global optimization of cerebral cortex layout". PNAS 101 (4): 1081–1086. doi:10.1073/pnas.0305212101. PMC 327154. PMID 14722353.
  5. ↑ Cherniak, C.; Changizi, M.; Kang, D.W. (1999). "Large-scale optimization of neuron arbors". Physical Review E 59: 6001–6009. doi:10.1103/PhysRevE.59.6001.
  6. ↑ Chomsky, N. (2005). "Three factors in language design". Linguistic Inquiry 36: 1–22. doi:10.1162/0024389052993655.
  7. ↑ Cherniak, C. (1981). "The Riddle of the Universe and Its Solution". In Hofstadter, D.; Dennett, D. The Mind's I. Basic Books.
  8. ↑ Cherniak, C. (2009). Saisho Gorisei. Keiso Shobo. ISBN 978-4-326-19953-2.

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