itions about various aspects of their environment are based on special-
ized principles. Causation is one among many examples of such prin-
ciples, as we will see presently. Also, the study of cognitive develop-
ment has shown with much more precision than before how some of
these principles appear very early in infancy and how they make it pos-
sible to acquire vast amounts of knowledge so quickly. At the same
time, imagery techniques that track blood flow or electrical and mag-
netic activity in the brain have reached a sufficient level of precision to
tell us which parts of the cortex and other brain structures are active in
different kinds of tasks. Finally, neuropsychologists have discovered a
whole set of cognitive pathologies that impair some inference systems [101]
while leaving the rest intact, which suggests how the system is orga-
nized.
WHEELS WITHIN WHEELS:
SYSTEMS IN THE BRAINIn this model, then, what makes our minds smart is not really a set of
encyclopedic descriptions of such things as artifacts and animals in
general but the fact that very specialized systems are selectively
turned on or off when we consider different kinds of objects. This
description is better than the previous one for several reasons. First, it
makes sense of the fact that some inference systems are activated by
several different kinds of objects. Goal-detection is applied to dogs
and to persons. Structure-function is applied both to artifacts and to
some body parts. Also, the way I talked of "ontological categories" as
if these were real kinds of things in the world was misleading because
many objects migrate from one of these so-called categories to
another, depending on the way we consider them. For instance, once
you take a fish out of the sea and serve it poached, it has ceased to be
only an animal and has become, to some extent, an artifact. If you use
it to slap someone's face, it has become a tool. It is of course not the
object itself that has changed but the kinds of inferences the mind
produces about it. At some point it seemed to be an "animal," which
means that our goal-detection system was activated when we looked
at it moving about and spontaneously wondered what it was looking
for. When we say that the fish has become an "artifact," what we
mean is that questions such as "who made it?" or "what for?" are now
produced spontaneously. When the fish has become a "tool," this
THEKIND OF MINDITTAKES