Unreal Nature

July 27, 2013

Imperfect Rationality

Filed under: Uncategorized — unrealnature @ 5:49 am

… To the extent that it is possible to understand [organisms] by reflecting on their origins it must be in terms of this [contingent, constrained] history, and this must take seriously the details of history over aeons. A project as simplistic as reverse engineering has no chance of pulling off this trick.

This is from Human Nature and the Limits of Science by John Dupré (2001):

… I suspect that part of the problem here is a very fundamental ambivalence common to many evolutionists. On the one hand evolution is universally seen as a scientific replacement for an earlier mystical view of the origins of life, a perspective with which I have much sympathy. On the other hand, it is quite obviously a historical subject, one that traces the particular vicissitudes of an exceedingly complex process on a particular seemingly insignificant celestial body. It is still common to think of science as showing how things had to happen the way they did by discovering the inexorable laws of nature that made them happen. But history, surely, is not like this.3 Laws may perhaps play a role in connecting specific events, but the view that the whole sequence of historical events is inexorably determined is a thesis in metaphysics not the theory of history. History itself is an indissoluble mixture of processes that seem more or less inevitable once under way, and entirely contingent events. Much misguided evolutionary thought can be seen as the futile attempt to make history necessitate and thereby to make a thoroughly historical study conform to the idea of science as the discourse of natural necessity.

… Organisms are highly complex structures, and aspects of their structures provide them with remarkable capacities to deal effectively with their environments. A paradigm is the eye. The eye, together with the parts of the brain that process information from the eye, is an exquisitely organized device for gathering information about the environment that surrounds an organism, and thereby for facilitating appropriate responses to that environment. It is impossible to avoid the conclusion that the function of the eye is to gain this information about the surrounding environment or, more simply, to see. Relating this more explicitly to evolution, it is said that the eye is an adaptation for seeing. Philosophical analyses of the concept of adaptation often explicitly include the assumption that an adaptation is a feature of an organism that exists because of the benefits it provided for ancestors.

… I said the eye was an adaptation for seeing. But it was not designed for seeing, since no one went to the trouble of designing it. One very important consequence of this is that it makes problematic a certain kind of atomism that is often assumed in analysing design. When designing the air-conditioning system of a car, say, one takes the rest of the vehicle as fixed and works out how best to cool its interior. This makes plausible the project that might be carried out by a rival car manufacturer of reverse engineering, trying to work out why the first manufacturer has done things the way they have by assuming that they were intelligently, perhaps even optimally, addressing the problem of cooling the interior of an automobile. Dennett considers this strategy, trying ‘to figure out what reason, if any, “Mother Nature” … “discerned” or “discriminated” for doing things one way rather than another,’ to be an ‘extremely fruitful and, in fact unavoidable’ one for dealing with organisms. The attribution of rationality to ‘Mother Nature’ is of course an ingenious way of converting history (natural history) into necessity. For as theologians have long understood, perfect rationality constrains the agent to only one possible action, which is to say that it necessitates an action.

Any design process takes place under constraints. The air-conditioning designer must start with the kinds of refrigeration units available or readily manufacturable, must find somewhere to mount it that is not already occupied by other essential components, and must generally take the shape, airflow, dynamics, and so on of the vehicle as given. But the constraints of ‘design’ facing Mother Nature are different in kind and in degree. Mother Nature does not, for instance, start off with a sightless human and work out the best way of equipping this creature with sight. It may be, as Richard Dawkins speculates, that the eye developed over aeons of time from a patch of light-sensitive cells somewhere on the surface of the body. But the ancient creatures with these patches of light-sensitive cells were nothing remotely like us. (Which is just as well as such a patch would probably not do us much good.) Each of the many stages between this ancient proto-eye and a modern human eye had to serve the particular kind of creature that was its happy possessor. Moreover the transition from, say, a creature with a patch of light-sensitive cells to a creature with a concave indentation filled with light-sensitive cells must have been constrained by the developmental and genetic possibilities of those particular organisms. And, as is well known, making genetic changes to an organism doesn’t typically make one local change, but often generates many changes that ramify through the developmental sequences of the organism.

None of this is supposed to be an argument that natural selection cannot produce adaptations. Natural selection provides by far the best, and perhaps the only, account we have capable of explaining the kind of functionality we find in physiology. But the process is a historical one, constrained at every point by historical contingencies of the moment.

… The fact that organisms originated from a long, complex, and constantly constrained historical process has momentous consequences. To the extent that it is possible to understand them by reflecting on their origins it must be in terms of this history, and this must take seriously the details of history over aeons. A project as simplistic as reverse engineering has no chance of pulling off this trick.

[ 3 Or at least not after the first second or two.]

My most recent previous post from Dupré’s book is here.



Blog at WordPress.com.

%d bloggers like this: