2001-06-19Z2011-03-11T08:54:41Zhttp://cogprints.org/id/eprint/1594This item is in the repository with the URL: http://cogprints.org/id/eprint/15942001-06-19ZDoes the Mind Piggy-Back on Robotic and Symbolic Capacity? Cognitive science is a form of "reverse engineering" (as Dennett has dubbed it). We are
trying to explain the mind by building (or explaining the functional principles of) systems that have
minds. A "Turing" hierarchy of empirical constraints can be applied to this task, from t1, toy models
that capture only an arbitrary fragment of our performance capacity, to T2, the standard "pen-pal"
Turing Test (total symbolic capacity), to T3, the Total Turing Test (total symbolic plus robotic
capacity), to T4 (T3 plus internal [neuromolecular] indistinguishability). All scientific theories are
underdetermined by data. What is the right level of empirical constraint for cognitive theory? I will
argue that T2 is underconstrained (because of the Symbol Grounding Problem and Searle's Chinese
Room Argument) and that T4 is overconstrained (because we don't know what neural data, if any, are
relevant). T3 is the level at which we solve the "other minds" problem in everyday life, the one at
which evolution operates (the Blind Watchmaker is no mind-reader either) and the one at which
symbol systems can be grounded in the robotic capacity to name and manipulate the objects their
symbols are about. I will illustrate this with a toy model for an important component of T3 --
categorization -- using neural nets that learn category invariance by "warping" similarity space the way
it is warped in human categorical perception: within-category similarities are amplified and
between-category similarities are attenuated. This analog "shape" constraint is the grounding inherited
by the arbitrarily shaped symbol that names the category and by all the symbol combinations it enters
into. No matter how tightly one constrains any such model, however, it will always be more
underdetermined than normal scientific and engineering theory. This will remain the ineliminable
legacy of the mind/body problem. Stevan Harnad