Tuesday, September 22, 2009

Nano-intentionality and Molecular Autonomous Agents

Intrinsic intentionality and inherent goal-directedness of eukaryotic cells is defended by Tecumseh Fitch and minimal molecular autonomous agents are characterized in "On emergence, agency, and organization" (by Stuart Kauffman and Philip Clayton).

The "aboutness" and "goal-directedness" of eukaryotic cells and how it relates to nano-intentionality is defined as follows (p14):
The crucial pre-mental properties of a cell are that it can
1) respond to (somewhat) novel circumstances, eventualities for which it is not specifically-prepared by the evolutionary "memory" instantiated in its DNA.
2) discover, through an individual process of trial and error, some "adaptive" (in the physiological sense) response or solution.
3) in various ways incorporate the results of this discovery into its own structure, thus "recording" or "remembering" (in a non-mental sense) this past, individual history.
It is argued that simple single-celled eukaryotes possess nano-intentionality and it is stressed that one of the abilities of a nano-intentional structure is its ability to rearrange its physical structure in response to environmental circumstances. An example of eukaryotic chemotaxis (sensory adaptation) in the amoeba and its ability to react to environmental signals and adapt to them by inducing structural changes was given, e.g. when seeking and ingesting food was given. Chemotaxis involves structural changes in response to environmental circumstances and it is not limited to eukaryotes as bacterial cells are also capable of chemotaxis. In this respect, bacterial cells would qualify since no other reason was provided for not including bacterial cells.

Kauffman and Clayton argue that the simple example of a bacteria that is able to swim up a glucose gradient is an example of an organism acting on its own behalf and they call such a system a "molecular autonomous agent". They continue to provide a tentative five part definition of a minimal molecular autonomous agents (p505):
Such a system should be able to
1) Reproduce with heritable variation.
2) Perform at least one work cycle.
3) Have boundaries such that it can be individuated naturally.
4) Engage in self-propagating work and constraint construction.
5) Be able to choose between at least two alternatives.
The earliest life forms emerged about 3000-3400 million years ago (ref) and were likely bacteria.

If anything, concepts such as "nano-intentionailty" and "molecular autonomous agents" highlight the doal-directed behaviour of entities or substances that are alive.