Evolved Function

There are two ways of describing an evolutionary process, just as there are two ways of describing a computational proces: (a) from an intentional perspective and (b) from a mechanical perpsective.  It is mistake to think that when we understand one we understand the other; and it is a bad mistake to think we can reduce the intentional to the mechanical.

It is possible that we may be able to 'reduce' the mechnical to the intentional, in the sense that we cannot understand rule following (and so mechanism) except in terms of a system falling under the scope of some intentional concept.

We can only render the evolution of function (an intentional category) intelligible by referring to higher functions.  If longer legs aid survival by allowing higher escape speeds, we 'explain' longer legs in terms of the function of speed ,whose relevance is the function of escape, whose relevance is the function of survival.  If we didn't understand what survival was, or why it was 'desirable', this explanation would have no force.

We could tell a different - much more complex - story about about the macrobiology of evolution, involving reproductive chemistry, the coding options available within DNA sequencing, genotype/phenotype relationships, protein folding and structure, environmental factors etc.  We can't, at present, tell enough of this story to be able to completely describe many large scale functional behaviours in terms of detailed mechanisms.  Even when we can do this, however, we will not be able to 'render' function as mechanism except by stipulation.  And this would expose our accounts of function to mechanical failure - just as if we tried to define a logical operator in terms of what a particular electronic digital component did.

In my last post I said we should think of machines as elements in a conversation between their designers and users.  When we discover a 'natural machine' we don't recognise the normative aspects of attributing function, and so we arrive at the argument from design.

And maybe this is lucky - especially if it is our visceral normative attributions which prevent us, on the whole, from seeing each other as machines.  Excessive intentional attribution is probably less dangerous to us than deficient intentional attribution.  From a functional point of view.