The late philosopher, Willard Van Orman Quine, who was for many years probably America’s most distinguished philosopher …. told me about a year before his death that as far as he was concerned, Darwin’s greatest achievement was that he showed that Aristotle’s idea of teleology, the so-called fourth cause, does not exist.
(Ernst Mayr, interview with Edge.org, 10.31.01)
And then again… did he? There is an interesting discussion going on at Telic Thoughts and the Evolution List on telic, teleomatic and teleonomic processes. Mayr’s position is that the appearance of design in nature is fully explained by Darwinian processes, and he chooses to describe the apparent purposefulness of living things as teleonomic, defined as "[a] processes or behavior which owe its goaldirectedness to the operation of a program". This is as opposed to teleomatic or deterministic forces such as gravity.
The "purposefulness", then, of biological organisms is an emergent property produced by natural selection; the writing of programs based on bits of information supplied by the environment.
Mayr defines a program as "coded or prearranged information that controls a process (or behavoir) leading it toward process (or behavoir) leading it toward a goal." and states that it contains "not only the blueprint of the goal but also the instructions of how to use the information of the blueprint." It is material and exists prior to the initiation of the telenomic process.
But do those definitions even begin to solve the problem? Is it reasonable to conclude that the emergence of teleonomic processes is explicable simply by reference to evolutionary mechanisms? As Allen states
Clearly, if the overall theory of macroevolution is valid, then there must have been a transition from teleomatic causation to teleonomic causation in biological organisms.
He suggest this transition takes place during the origin of the genetic code; a likely choice, given that necessay origination of a program there. Certainly the simple molecules of a hypothetical prebiotic soup would have been only teleomatic, and yet the first functioning cell contained a complete program. Somehow in the interim we have managed to build not only the program itself, but also a machine with the capability of reading the program and turning it into action.
The only emperically known source of programs are already-teleonomic entities, and the only observed causes of machines capable of turning instructions into action are intelligent, purpose-driven creatures. In Cell Biology International Abel suggests that the origin of life is theoretically irreducible to chance and necessity, and Yockey has argued similarily in other papers. Is this indeed demonstrable, or will we always be able to insert our favorite cure-all– natural selection, fairies– into an ill-defined gap?
[All definitions from "The Idea of Teleology", Ernst Mayr, Journal of the History of Ideas, Vol. 53, No. 1. (Jan. - Mar., 1992), pp. 117-135; avalable here if you are in the Cornell network]