Curve and lattice

In my previous entry I discussed a talk at Neukom ‘08 by Daniel Dennett where he revises his model of consciousness to account for recent thought regarding competition for resources within the brain. He refers us to a paper by Tecumseh Fitch which both provides a detailed explanation of how this competition came about and offers a defense of intrinsic intentionality—the possibility of things being intrinsically directed toward other things.

Fitch begins by providing his interpretation of Dennett’s thought in The Intentional Stance. He sees Dennett’s work as a full-force attack on the possibility of intrinsic intentionality (all citations Fitch 2007):

The thrust of Dennett’s argument is that this “something” (which he terms variously “original” and “intrinsic” intentionality) is an illusion, a deep philosophical mistake that derives from our unwillingness to fully bite the bullet and accept natural selection (and its products, especially ourselves) for the blind and goal-less process that it is. Dennett criticizes intrinsic intentionality with arguments that need to be taken seriously, arguments which seem to force us into a corner where we must choose between the following propositions: either accept that all intentionality, including our own, is derivative (and then admit that a thermostat has a little bit of intentionality, too), or we retreat from this unpalatable option into a mysterian, outmoded belief in “original/intrinsic intentionality”, a concept that under close scrutiny leads to contradiction and paradox at every turn.

At Neukom, Dennett says Fitch misinterpreted his work on intentionality, but doesn’t explain exactly how. Regardless, he thinks Fitch is right, and he’s on board with nano-intentionality and its implications.

From the beginning of his paper, Fitch focuses on a key difference between living things and machines: the ability of living things, especially small ones like cells and neurons, to adapt to local circumstances by changing their shape. Formal changes act as both a kind of memory and a way in which the cell is “about” its environment. This inherent, formal aboutness is nano-intentionality. Fitch argues that the kind of inherent intentionality we attribute to minds is a consequence of the nano-intentionality of cells and neurons. “When combined properly into large interconnected systems, this combined mass-action of cellular nano-intentionality yields intrinsic intentionality in the typical philosopher’s sense, as well as both consciousness and the efficacy of our subjectively sensed self to move the body and perform other acts of will (‘intentionality’ in its general English sense), just as the mass and velocity of gas molecules contained in a volume are constitutive of its temperature, pressure and weight.”

Here is how the argument evolves: Start with an amoeba. We understand much of how amoebas work on a mechanical level, and we know they came to behave this way because of natural selection. This is Fitch’s “prototypical example of [...] nano-intentionality”. The “purpose” of an ameoba is “realized via its physical form: it is a complex arrangement of matter serving to do useful things like find food and avoid toxins”, etc. Critically, an ameoba can deal with novelty using trial and error, “remembering” successful strategies by modifying its form. In contrast, a thermostat can only interact with what it was designed to interact with; it is only “about” what it was designed to be “about”. But an ameoba is about its whole environment, a world of things.

In multi-celluar organisms, groups of specialized nano-intentional cells cooperate, creating intentional subsystems which are “about” different things. Fitch’s example is the sponge. Each subsystem in the sponge is “about” something different, like creating efficient water flows or digesting. Fitch argues that the intentionality of these groups allows the sponge to be intentional itself, independent of an observer taking Dennett’s intentional stance. A sponge is “about” filter-feeding because its constituant parts allow it to filter feed, because the sponge evolved that way. “The aboutness of the sponge is reflected in its structure, but is constituted by its evolutionary history: the story of sponge-kind.” I.e., the way in which individual cells are “about” their environment changes when their environment contains other, collaborating cells: a kind of group intentionality emerges. The same is true on the next level of abstraction: collaborating groups of groups of cells like a sponge.

Next Fitch looks at jellyfish. They have a basic nervous system, a nano-intentional subsystem which is about information processing. In the nervous system, neurons don’t just collaborate with other neurons to perform a simple task like flaggellation, they interact with each other, such that structural changes in one cell are changes in the environment of the others. Indeed, a change in the nervous system of an organism is a change in the environment of many other cells in that organism, neurons or not. Neurons are “‘about’ amplification of information into locally adaptive patterns of action”. Neuronal events, however, are about whatever environmental change triggered the event. The organism as a whole can now react to the world around it. Fitch calls systems with this capacity “proto-mental.”

Fitch goes all the way up. The nervous system evolves from simply reacting to environmental changes, to representing those changes, and eventually to acting as a generative model, a source of ideas about “possible worlds”. Neuronal assemblages which are successful, i.e. whose representations correspond to actions actually taken by the organism in the world, are “tagged” by other neuronal assemblages, and from this emerges the serial experience of consciousness. Here we have intentionality in the philosopher’s sense, and a theory about how it arises. Fitch concludes that any system which has this kind of possible-world-tagging system must have some subjective experience, some awareness:

“To the extent that this argument is correct, awareness is the intrinsic subjective side of an objectively-verifiable capability of some types of nervous system to both entertain multiple hypothesis at a given time, and to later learn from their mistakes and successes. This leads to a rather strong and surprising thesis: that any nervous system objectively capable of considering and choosing among mental options, and of learning from its past decisions, will have at least a little bit of awareness as it does so: a little bit of (serial) consciousness.”

Fitch is, essentially, biting the natural-selection bullet offered by Dennett. But rather than looking for ways in which some internal mind could interface with an external world, he shows us how mind and world are inextricably related, and how directedness emerges from this relation.

The paper also includes an interesting discussion of how this way of thinking will affect artificial intelligence research, among other things.

References:

Dennett, D. How Mindless Algorithms Build Minds. May 9, 2008. Online video clip, accessed on July 21, 2008. http://neukominstitute.com/index.php/site/feature/dennett_talk/symposia/49/symposium08

Dennett, D. (1987) The Intentional Stance. MIT Press.

Fitch, W.T. (2007) Nano-Intentionality: A Defense of Intrinsic Intentionality. Biology & Philosophy, Vol. 23: 157-177.