new computationalism ron chrisley cogs department of informatics university of sussex school of...
TRANSCRIPT
New Computationalism
Ron ChrisleyCOGSDepartment of InformaticsUniversity of Sussex
School of Humanities and Information, University of SkövdeOctober 19th, 2006
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Overview
Will discuss four related claims/ideas:1. "Transparent" defense of
computationalism2. Falsity of the Church-Turing thesis3. Falsity of pan-computationalism4. Even if computationalism is false,
strong AI is possible
Transparent computationalism
• The claim that cognition is computation can be construed opaquely or transparently
• Opaque construal: The mind is best understood in terms of the concepts from current (or past!) computational theory
• Transparent construal: The mind is best understood in terms of whatever concepts, it turns out, best explain what computers do
• Many critiques of computationalism succeed only on the opaque construal
• Thus, transparent computationalism is not threatened
The transparent strategy
• For each critique, present:– A current (opaque) view of
computation– The critique based on that view– An alternative view of computation
that avoids the criticism– Independent motivation for that view
of computation
Critique 1: Dynamics
• Opaque view: Discrete steps in an algorithm essential to computation
• van Gelder:– Cognition isn't discrete, but
fundamentally dynamical– Therefore, cognition isn't computation
Dynamical computation
• Alternative view: Generalise notion of an effective procedure to include any physically realisable and exploitable process, even dynamical ones
• Independent motivation:Real-time computational control of an airplane wing
Critique 2: Externalism
• Opaque view: Computational properties are syntactic and local
• Fodor:– Psychological properties are semantic
and relational/external/non-local– Therefore, there can't be a
computational psychology
Externalist computation
• Alternative view: Even computational explanations are external/relational (cf Peacocke's "Content, computation and externalism", 1994)
• Independent motivation: Embedded computational systems
Critique 3: The Chinese Room
• Opaque view:1. All essential computational properties are
formal2. Non-formal properties of a computation are
mere implementation detail
• Searle:– Formal properties are insufficient for mind– Therefore, there can't be a computational
psychology
Grounded computation
• Alternative view:1. Having a semantics is crucial to
computation 2. Some properties that current formal theory
takes to be irrelevant play a constitutive role in determining computational state
• Independent motivation:1. Not every process is a computation2. Real-time computational control of an
airplane wing
The Church-Turing thesis
• An example of an explicit acknowledgment of the distinction and relation between informal and formal (theoretical and pre- theoretical) notions
• Diagonal arguments (Gödel, Lucas, Penrose) do not show what they purport to: falsity of Strong or even weak AI
The Church-Turing thesis
• Diagonal arguments highlight a special case of a general property:– For any set of things that can answer
questions, one can construct a question that no member of that set can answer, even though some things outside the set can.
• Implies, e.g., that odd-numbered TMs can compute functions that even-numbered TMs cannot
• And that TMs can compute functions we cannot
Universality
• One might think this violates Turing's famous result, that there exist universal machines
• But no conflict, since Turing's universality result is about simulation, not computation
Against pan-computationalism
• Putnam's sense: Everything instantiates every computation– fails because of the causal aspect of
causation (cf, e.g., Chalmers 1994, Chrisley 1994)
• More plausible sense: Everything has some computational desciption– Yes, but still too broad: IBM vs BMW– Suggests that we need to do more work to
capture real computation: Semantics
Computation and mind
• Traditionally, two ways computation is relevant to understanding or replicating mind:
1. Weak AI: Computational simulation of mind
2. Strong AI: Cognition is computation
Strong AI without Computationalism
• Even if cognition is not computation, does not imply falsity of strong AI– Not because of pan-computationalism– Third way: computation as the ultimate
plastic– Computation is a convenient way to
configure a system's causal/dynamical profile
– In between identity and mere simulation
Strong AI without Computationalism
• E.g. Suppose life is crucial for mind; and (e.g.) Boden is right that life is non-functional – Does not imply that one cannot
program a system to be alive – Falsity of (even transparent)
computationalism does not imply Strong AI is impossible
Thank you!
Video, audio and PowerPoint files of this talk and others can be found at:http://e-asterisk.blogspot.com
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