Related obliquely to the discussion about pattern discovery algorithms.... What
is a symbol?
I am not sure that I am using the words in this post in exactly the same way
they are normally used by cognitive scientists; to the extent that causes
confusion, I'm sorry. I'd rather use words in their strict conventional sense
but I do not fully understand what that is. These thoughts are fuzzier than
I'd like; if I was better at de-fuzzifying them I might be a pro instead of an
amateur!
Proposition: a "symbol" is a token with both denotative and model-theoretic
semantics.
The denotative semantacs are what makes a symbol refer to something or "be
about" something. The model-theoretic semantics allow symbol processing
operations to occur (such as reasoning).
I believe this is a somewhat more restrictive use of the word "symbol" than is
necessarily implied by Newell and Simon in the Physical Symbol System
Hypothesis, but my aim is engineering rather than philosophy.
I'm actually somewhat skeptical that human beings use symbols in this sense for
much of our cognition. We appear to be a million times better at it than any
other animal, and that is the special thing that makes us so great, but we
still aren't very good at it. However, most of the things we want to build AGI
*for* require us to greatly expand the symbol processing capabilities of mere
humans. I think we're mostly interested in building artificial scientists and
engineers rather than artificial musicians. Since computer programs,
engineering drawings, and physics theories are explicitly symbolic constructs,
we're more interested in effectively creating symbols than in the totality of
the murky "subsymbolic" world supporting it. To what extent can we separate
them? I wish I knew.
In this view, "subsymbolic" simply refers to tokens that lack some of the
features of symbols. For example, a representation of a pixel from a camera
has clear denotational semantics but it is not elaborated as well as a better
symbol would be ("the light coming from direction A at time B" is not as useful
as "the light reflecting off of Fred's pinky fingernail"). Similarly, and more
importantly, subsymbolic products of sensory systems lack useful
model-theoretic semantics. The "origin of symbols" problem involves how those
semantics arise -- and to me it's the most interesting piece of the AGI puzzle.
Is anybody else interested in this kind of question, or am I simply inventing
issues that are not meaningful and useful?
-------------------------------------------
agi
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