Contrary to what ID theorists have claimed, Evolutionary Theory can give a fully adequate explanation of the appearance of design and of the organizational complexity of living systems in terms of random variation and natural selection. However, in what is clearly a response to critics, Ayala writes: These adaptive combinations constitute, in turn, new levels of organization upon which the mutation random plus selection nonrandom or directional process again operates.
There is a place in biology for teleological explanations.
Ayala distinguishes systems with teleological features that are caused by a natural process, such as the wings of birds internal , from those that are the result of a purposeful agent, such as a knife external. For "there was nothing in the constitution of the remote ancestors of birds that would necessitate the appearance of wings in their descendants …. At each stage [in their development] the most advantageous alternative was selected among those that happened to be available; but which alternatives were available at any one time depended, at least in part, on chance events.
Ayala's stark formulation of natural selection as a creative process, "subject to the vagaries of genetic mutation and environmental challenge" and without "a preordained plan, whether imprinted from without by an omniscient and all-powerful Designer or resulting from some immanent force driving the process towards definite outcomes" pp. In spite of Ayala's well-chosen, plausible examples illustrating his claims, it is easy to see why ID theorists see this account as containing large explanatory leaps that need a lot of filling in.
Also, one wonders whether Ayala can help himself to so much teleological description without its forcing some shift toward teleology in the underlying mechanisms. Defenders of Intelligent Design theory Dembski, Michael Behe, Walter Bradley, Stephen Meyer present arguments that purport to show that the accepted evolutionary theory fails to explain various aspects of living organisms, viz.
Dembski and Bradley lay out similar arguments based on the precisely calculated improbability of complex specified information such as we find in living systems like the flagellum Dembski or in biopolymers DNA, RNA, and protein Bradley. Dembski writes that the probabilities of these complexly organized systems evolving by material mechanisms "are horrendous and render natural selection utterly implausible as a mechanism for generating the flagellum and structures like it. Although Dembski's and Behe's arguments for the non-reducibility of the flagellum are essentially negative -- aimed at showing what evolutionary theory has not explained and cannot explain -- Dembski insists that the argument is based on positive empirical evidence.
The Dembski and Behe essays should be read in conjunction with Weber and Depew's contribution, "Darwinism, Design, and Complex Systems Dynamics," which takes up the challenge of explaining how some systems with CSI, such as the immune system and blood-clotting, could plausibly have emerged from simpler systems via Darwinian processes.
Scientific work aimed at testing scenarios that have recently been proposed for blood clotting "is proceeding and is beginning to provide the basis for shifting to the question of 'why actually ' [and not merely 'how possibly'] such a complex cascade has actually arisen in evolution by natural selection. Dembski is unimpressed by these sorts of proposed Darwinian histories, arguing that they only meet the challenge if the probability of each step in the proposed series is 1 quantifiable; 2 reasonably large; and 3 constitutes an advantage to the evolving system.
The first two of these requirements seem overly strict and to reflect Dembski's preferred methodology; and the third is met if simpler systems or components can be shown to have some function. But what is significant about this exchange is that ID theorists have raised questions that have sparked new thinking and research from evolutionary theorists. This research program appears to be only in its beginning phase pace Miller , and whether it will succeed in giving "how-actually" explanations without causing revisions in the general theory remains to be seen.
But the main obstacle to the Design hypothesis achieving scientific consideration is that no attempt is made in any of these papers to specify how the intelligent agent causes complex specified information; that is, the hypothesized activity of the designer is not defined operationally. The hypothesis then, whether supernatual or natural, remains so general and unspecified that scientists literally couldn't do anything with it even if they wanted to. This criticism is illustrated in this volume by Pennock's challenge to Meyer who argues that evolutionary principles cannot account for the Cambrian explosion to state specifically what the intelligent designer is supposed to have done to bring about the Cambrian proliferation.
This viewpoint agrees with the negative thesis of Intelligent Design theory that evolutionary principles are inadequate to explain life, but does not seek that explanation in any external intelligent cause.
What is needed instead is a redefinition of living matter and its mode of functioning. The Argument from Design: A Brief History -- Michael Ruse 3.
The first two of these requirements seem overly strict and to reflect Dembski's preferred methodology; and the third is met if simpler systems or components can be shown to have some function. These adaptive combinations constitute, in turn, new levels of organization upon which the mutation random plus selection nonrandom or directional process again operates. Cambridge University Press Bolero Ozon. Or, does the appearance of design signify genuine prevision and teleology, and, if so, is that design empirically detectable and thus open to scientific inquiry? He is the author of many books, including Can a Darwinian Be a Christian?: Swinburne's philosophical argument for God is the exception; his cosmological argument is squarely in the tradition of natural theology, as is the Design Inference. Trivia About Debating Design:
Who's Afraid of ID? Darwin's Greatest Discovery -- Francisco J.
The Design Argument -- Elliott Sober 7. Prolegomenon to a General Biology -- Stuart Kauffman 9. Weber and David J. Design without Designer Darwins Greatest Discovery. Stephen Meyer and the Return of the God Hypothesis.
Darwin Design and Divine Providence. The Inbuilt Potentiality of Creation.
The Argument from Laws of Nature Reassessed. The Logical Underpinnings of Intelligent Design. Prolegomenon to a General Biology. Darwinism Design and Complex Systems Dynamics. Emergent Complexity Teleology and the Arrow of Time. The Emergence of Biological Value.