Incomplete Nature is about an important and difficult subject: how life and mind evolved from a world of inanimate matter. It is also about what are the right concepts to use in understanding the nature and workings of life and mind. We need to be able to conceive them in such a way that it becomes intelligible that they could have arisen naturally from the kinds of inanimate processes described in physics and chemistry.
Terrence W. Deacon approaches these questions with the apparatus of dynamic systems theory, which describes the operations of complex systems that are autonomous, self-maintaining, stable over time, and resistant to the tendency toward disorder called entropy. The model of such systems, at a primitive level, is the biological cell, which makes up further more complex dynamic systems such as organs and whole organisms. The cell maintains its integrity over time by means of an enclosing membrane that is selectively permeable, letting in only such molecules as will serve its self-preserving needs: performing basic metabolism and expelling waste products. It is a self-organizing unit (unlike a humanly constructed machine) that admits of teleological description—it has goals toward which its activities tend—and that contains the essential ingredients of life. One of its central capacities is counteracting the effects of the second law of thermodynamics: it creates order and resists chaos. Some cells have a further capacity—the capacity to produce copies of themselves. In these capacities life ultimately consists.
Deacon’s strategy is to try to show that such a basic biological form could arise from something yet more primitive, which he calls an “autogen.” The thought is that stable but active inanimate systems, like whirlpools, tornadoes, and “autocatalytic molecules”—systems that maintain their existence notwithstanding material interaction and change—might provide the conceptual perspective that enables us to see how primitive life might have evolved.
We have, Deacon says, to imagine a molecular compound that maintains itself by taking in energy from its environment and creating the chemical structures that define it (this process is often called “autopoiesis”). The advantage of this way of thinking is that we avoid certain theoretical pitfalls—chiefly “saltations,” “homunculi,” and “preformationism”: that is, respectively, unexplained leaps forward in the evolutionary process, surreptitiously introduced forms of intelligence that direct the proceedings, and postulating that the evolved entity was really there all along (as if cells existed at the time of the big bang, but invisibly). What we are seeking is a theory of emergence that demonstrates continuity with what was there before, while not supposing that it was present at the beginning. Then, and only then, we shall understand how life and mind might spring from a world of lifeless insensate matter.
I shall divide my assessment of Deacon’s lengthy disquisition on these issues into three parts: his style of writing, his originality, and …
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The Search for Sentience October 11, 2012