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These are excerpts and elaborations from my book "The Nature of Consciousness"
Intentionality (the ability of a
system to refer to something outside it) is at the center of the philosophical
debate on meaning.
Willard Quines instrumentalist
theory rejected intentionality altogether, considering it merely a linguistic
trick. Quine thus denied psychology (that deals with desires, beliefs and hopes
and so forth) the status of science.
Daniel Dennett reached a similar conclusion: the intentional stance is simply one
of the possible ones, and it is just that, a stance. It is useful to attribute
intentional states to other humans, and maybe even to non-human systems.
Intentionality is only a feature of our language, a tool. The mind is not
intentional because it does not exist, it is only a term in the vocabulary of
folk psychology. The brain is not intentional because its states do not refer
to anything: they simply are what they are, just like in any physical system.
Jerry Fodors representational
theory, instead, posits that the brain literally contains the intentional state
that we ascribe to the mind. For Fodor, the vocabulary of folk psychology is
a scientific language: it describes facts that are really happening in the
brain, not just linguistic tools.
The US philosopher Ruth Millikan argued that intentionality is an objective, natural, biological
feature of humans, that evolved over millions of years just like any other
organ or limb of the human body. Intentionality is no more than the biology of
belief, desire, hope and intention, which must be treated like any other
biological object. Propositional attitudes (beliefs, hopes, desires,
intentions) are biological devices, designed by evolution to have some effects
on us. That effect is its content. Thus the effect has been determined by
evolution. This strategy of treating intentionality as a biological feature can
be extended to treating meaning as a biological phenomenon (biosemantics),
because each sentence can be viewed as having a biological function (typically,
helping us live in the world). Sentences are basic intentional items.
Intentionality is grounded in the relationship with the environment, a
relationship determined by evolution. A mental content is the effect of a
biological system designed by evolution to have that effect. Presumably,
Millikan believes that desires and beliefs are physiological features of the
brain, because they have evolved from generation to generation just like any
other bodily organ has. On the other hand, the contents of these beliefs and
desires are located outside the brain, and can be understood only by
understanding their biological function, i.e. their evolutionary history. A
belief is similar to the dance of a bee, a biological feature designed by
evolution that refers to an object outside the head of the bee.
The externalist theory of the
British philosopher Colin McGinns is an extension of
Millikans teleological theory. The mental content of humans is external to
their minds for the simple reason that it was set by evolution and it refers to
the environment. The cognitive life of humans has been shaped by evolution to
cope with an external object, the environment. Beliefs and desires are brain
states whose content is a relation to the external world.
The information-processing theory
of the US philosopher Fred Dretske assumes that cognitive life consists in transforming analogue
information (that comes from the sensory system) into digital information (that
can become the processed as knowledge). For example, a smell per se is only a
set of sensory data. Once it is analyzed and turned into the information that
it corresponds to, the smell of a particular flower, we know a fact about the
world. This transformation from analogue to digital is what creates a belief.
A belief is therefore a neural structure. This is what the system believes.
The content of that belief is thus defined by its informational origin and not
by its behavioral effect. A concept is the link between the information origin
and the behavioral effect. The semantic content becomes a cognitive content
when it is transformed from a representational unit to a functional unit.
In the functionalist theory
of the British philosopher Brian Loar beliefs and desires are real
physical states with real causal powers, but they are wholly defined by and
within the overall network of beliefs an desires. A belief is defined by its
functional role within the network of the persons beliefs. In a sense, the
mind is the network of prepositional attitudes. The US philosopher John
Searle thinks that intentionality can
only be relative to a contextual "network" of other intentional
states and to a "background" of pre-intentional stances. The
background is necessary for the network to function. In other words, in order
to perform a mental act, one must have a network of mental acts and they must
be grounded in the real world. For example, I can "desire to see a
film" only if I believe that the film exists and is showing. Thus the
"network". And i can go and see the film only if I know how to drive
the car and how to find the address. Thus the "background". Back to the beginning of the chapter "Meaning: Journey to the Center of the Mind" | Back to the index of all chapters |
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