Evolving Thoughts

Evolution, culture, philosophy and chocolate! John Wilkins' continuing struggle to come to terms with impermanence... "Humanus sum, nihil humanum a me alienum puto" - Terence

Tuesday, March 29, 2005

Doing without design

So, I must continue to deal with design, it seems (curse those lurkers!)...

I will now move from the boring part - intelligent design and the various other attempts to revivify the argument from design. Let us instead look at design in evolution itself.

It is commonly said that design, in the guise of adaptation, is a core element of evolutionary theory. I want to make a somewhat radical suggestion - let's lose all mention of it unless we are, as Bacon allowed, talking about human motivations. There is no design in biology. Adaptation is not producing "design-like" or "designoid" objects. There is only ever design in a single place - between the ears of observers of biology, whether they are specialists or naive.

Design is context-sensitive to the interests of the designer, not the interests of the observer. We project ourselves onto the natural world all the time - we've done this since the earliest recorded times. Plato did it. Aristotle did it less (and the Neo-Platonists Plotinus and Porphyry did it more). But that doesn't mean the world is under any obligation to behave the way we think, or like us. Anthropomorphism is a Bad Thing.

People, like Dawkins, who say that evolution produces "designoids", or "information", or "function", or "purpose", take ascriptions from the human domain and apply them to the non-human, and non-cognitive domain. We say that a screwdriver has a function because we use it for one. The function of a screwdriver for a manufacturer or retailer is to increase profitability. But the function of an aspect of a living organism is, simply put, whatever the model used to describe and explain it ascribes. When you look at the number of models that can apply to, say, a structural element of a cell like an actin filament or an mRNAse, each one ascribes a function, a purpose or a "design".

Design and its cognate terms are projections. The question is not whether they are projections, but in what circumstances it increases our knowledge of the things we ascribe them to. In other words, when is the function of a model properly applied to the thing modelled?

The answer is a purely epistemic one: when the model successfully describes the thing. Actin filaments have a role in the development of, say, William's Syndrome. So the "function" of actin has a role in the normal development of glial cells and neurons. But actin also is a key element in the structural integrity of single celled bacteria. It has a "function" in maintaining and changing shape. It also plays a role in muscle contraction, and cell motility, and so on. Each of these is, in the appropriate (that is, the applicable) context, part of its function. But although it might play a role in sharpening pencils, and in the relevant model it would have that "function", it actually doesn't.

Designs are abstractions based on how we model things. Functions and goals are likewise. Information is a property of the way a physical structure (usually the primary sequence of a polymer) is symbolically described - you get a different information content when you symbolically describe the primary sequence of a stretch of DNA as "GTAC" than if you described the hydrogen bonds or the numbers of protons or the energy shells of the atoms. It suits us to use the nucleotide abbreviations; but it may also mislead us. Sometimes the weak and strong bonding points on a primary sequence are more important than the sequence itself, biologically speaking, for these will affect folding, expression, and error-correction (this last being an abstract way to speak of mismatch repair).

So I want to go the whole deflationary hog. Let's stop talking about these abstract properties of biology, and just talk about the biology. What shall we miss? Nothing, since function and goal is only a metaphorical way to express actual physical properties and quantities. Of course, we may continue to use these terms on the understanding that they "stand for" real things, and that the metaphors are only for convenience. Would that it were that simple. We intentional animals keep falling into the trap of mistaking the periphrases for the facts.

So I want not just a desert ontology, as Quine proposed, but a rigidly physical one, in biology. Evolution is not a process of producing information, goals, or functions. It is a process of physical systems that make more or less accurate copies of themselves in environments of more or less stable thermodynamic and spatial properties. There's nothing that can be called "information" that doesn't involve, in my opinion, a clear analogue to a Shannon system of sender-channel-receiver. Perhaps cell--cell signaling qualifies. Certainly, neural systems do. Genes? Not on your, or any other organism's life.

Think of the confusion that would be avoided. Think of how we would be able to see clearly that we aren't talking about computers, programs, goals, intentions, purposes or plans. Just living things...

Bet nobody agrees.