Intelligent Design as a Scientific Theory


Intelligent design (ID) has been proposed as an alternative or a modification to the theory of evolution. Evolution is a scientific explanation of how there came to be so many different forms of life on Earth. It also explains how there came to be similarities between different types of life form, and differences between individuals of a particular type. Evolution attributes all these differences and similarities to natural processes. It supports and is supported by, but should be distinguished from, those sciences that describe details and processes of known life forms, relationships between life forms, and the time sequences of living and extinct forms.

ID proposes that an intentional process of design is, or was, necessary to produce some or all forms of life. Its proponents claim that many features of organisms could not have arisen as described by evolutionary theory, or, in their words, are "too complex to have happened by chance". Commonly quoted examples of such complexity are human beings and such organs as the eye. Many scientists have criticised the idea of intelligent design. They claim that it is unscientific, and just another form of creationism proposed in opposition to evolution for religious reasons.

While this may be true, it doesn’t always need a belief in a particular religion for someone to be persuaded that ID is more likely than evolution. A feeling that "there must be a reason behind everything" combined with wonderment at some aspect of nature may be enough. But many committed Christians accept evolution and reject ID.

Some proponents of ID accuse supporters of evolution of being constrained in their thinking and guilty of scientism, that is, of having a blind faith in the truth of science. While the usual view is that science is always subject to correction, however well it fits all that has been discovered about the world, some scientists and others do have blind faith in its truth, including the theory of evolution.

But scientific theories should be judged on their own merits, irrespective of the behaviour, beliefs or motives of their proponents.

Scientific Theory

Because it has been raised as an alternative to or, perhaps, a component of evolution, ID deserves impartial examination as to whether it is a credible scientific theory.

Theory is one of the two components of science, the other being observation - that is, observation of any and all aspects of the world. To be accepted, observations (which often include measurements) should be continually and rigorously confirmed by independent observers, using, where possible, independent methods of observation. We usually then think of them as facts.

Theory is the explanation that logically links all observed facts. There have always been observations for which no completely consistent logical explanation could be found, and theoretical scientists continually "think outside the box" in search of new explanations, which must then be tested. Proponents of ID say they are doing just that. I propose to look at ID as a theory, including implications of its basic concept and what it might explain better than evolution can. To do this I will first sketch out some aspects of evolutionary theory.

evolutionary explanation of the development of species

The basic concept in evolution is that when organisms reproduce, the offspring are similar to but often slightly different from their parents. Occasionally the differences give the offspring some survival and reproductive advantage, which may lead to gradual predominance of the new form. If, over many generations, advantageous changes accumulate, significantly different life forms develop. This is a continuing tentative natural process that enables species to selectively adapt to their environments, making the most of opportunities in the presence of competitors, predators and parasites, which also have developed in the same process. It is not at all like "a whirlwind in a junkyard assembling a Boeing-747", as the eminent physicist Fred Hoyle once described evolution.

The (inheritable) differences between parent and offspring are explained by observed processes, mainly changes ("mutations") to their genetic material, ie, their DNA. All living organisms are structured and operate in accordance with "recipes" coded into their DNA. Mutations continually occur in DNA because of irregularities in the workings of the cells, caused by exposure to unusual chemical conditions, extraneous DNA or radiation. In most cases the internal controls within the cell correct the change. In most other cases the effect of the change is trivial or harmful. In a few cases the change gives some advantage, at least for the environment that the organism finds itself in.

Evolution can be illustrated using the development of a complex organ, the eye. A long series of tiny steps starts with a mutation that produces a blob of tissue that happens to cause a reaction affecting the organism when light falls on it. Each successive step provides additional advantage, such as registering the direction of the light, improving focus, and distinguishing detail, colour and movement, producing the many different types of eyes observed among a wide range of species. For each change to be viable, other parts of the organism need to be able, perhaps initially not very well, to take advantage of it.

We see evolution operating in some of the species we have unsuccessfully tried to exterminate. We see it in the fossil record, where, despite many undiscovered steps (the "missing links"), scientists can "join the dots". And they continually find evidence to fill the gaps.

Richard Dawkins has described evolutionary processes so persuasively in his books, such as The Blind Watchmaker and Climbing Mount Improbable, that they seem to be self-evidently true. But Newtonian mechanics also seems self-evidently true. So might there be a successor to evolution - the biological equivalent of relativity? Such a theory need not discredit evolution, but refine or reorientate it. Could intelligent design be such a theory?

A new scientific theory should be able to predict future discoveries. So, what predictions were made by the theory of evolution? When it was first formally proposed there was little evidence of sequential development of the various species, but it was predicted that new fossils would be found that, together with known fossils, would demonstrate chains of development, and that evidence of the ages of various fossils would support the associated developmental sequence. New fossil finds did indeed do just that. And as new sciences developed, eg, molecular biology and the various methods of establishing the age of fossils, the genetic relationships and time sequences discovered continued to confirm the predictions and to correct some assumptions about earlier discoveries.

This should not stop any alternative explanation from being considered. But if an alternative is proposed, it should also propose a process that does not contradict observed fact. A competing theory should also show how it overcomes any failings of evolution. So, what are the failings?

Critics point to evolutionary explanations of such things as why in human beings the life span is much longer than the period of reproductive ability (in contrast to other species) or how various social characteristics arose. These are speculative stories that often sound plausible and might be shown to have parallels in computer models. But they are generally incapable of being tested or of leading to testable predictions. Often they are countered by alternative speculations that also invoke evolution. Sometimes they may be useful in investigation or therapy. Similarly, there are arguments among biologists and palaeontologists about how evolutionary processes best fit specific observations.

Another perceived failing is the purposeless or apparent mechanistic feel of evolution. This offends the intuitive expectations of many people, who consider that life has some spiritual aspect. This is not a scientific objection, and would be hard to defend in any scientific argument. But the evolution of consciousness from inanimate matter is something that scientists and philosophers still debate.

These arguments are about biology, palaeontology, etc, and have no bearing on the credibility of evolution as a theory. Similar arguments abound in most sciences.

Biologists have as yet produced no satisfactory theoretical series of possible steps by which inanimate matter might have developed into living organisms. This is neither a concern nor a refutation of evolution, which is about differentiation of species not the origin of life. But if intelligent design proposed a feasible observable process it would indeed be a new breakthrough.

However, the key argument is that the type of incremental changes proposed by evolution could not possibly produce such complex forms. Biologists, palaeontologists and geologists consider that there is ample evidence to refute this objection, which will be examined in more detail later.

Prevailing theories, including superseded ones, have always had plausible defences against objections. New theories – like continental drift and Helicobacter pylores – often have a hard time. But if they can convincingly address the evidence and solve niggling problems they will prevail. So what about ID?

Implications of a designer

Intelligent Design as a Scientific Process

ID proposes that desired new forms of life have been intentionally brought into being. No observed natural process supports this, so additional ones would be required. None seem to have been proposed or predicted – at least in the peer-reviewed scientific journals - so I will suggest what a serious theory would need to propose.

It seems reasonable to expect a theory of ID to include conceptualisation, detailed design and assembly. The design might be expressed into the genetic code (which would require comprehensive and precise knowledge of the function and activation of the code). The designed organism would then be assembled using materials in a "construction factory", perhaps by inserting the associated codes into a cell as is now done in genetic engineering or cloning. But what type of cell, and how would it be nurtured to adulthood?

Alternatively, entire adults might be assembled, but, if so, how?

And what, specifically, is designed: each species separately, or just some key beginnings and processes? If the latter, it seems very close to evolution, as some ID proponents think. In all cases, the theory needs to propose processes, showing how each design becomes a living organism, how separate species emerge, why there are differences between individual members of each species, how successive generations of a species develop adaptations to environmental conditions and how some members of a species are born with DNA-related diseases. This might imply separate, and sometimes faulty, design of each member of each species, including, perhaps, micro-organisms.

Alternatively, the designer might have produced the mutations that evolution attributes to natural causes. But how? And what prompts trivial or harmful mutations? And what about the natural causes of mutations that have already been identified?

Clarifications and proposed processes for these and any other issues would need to be compatible with the consistently observed biological and physical processes and/or predict the discovery of new processes.

The Designer

A theory of ID would not be complete or sufficient without proposing relevant attributes of the designer. It would need to describe what prompts or compels the designer to make and implement a design, how the designer determines the details of each specific design, and how the designer knows about and interacts with what we call the material world. If new types of forces and/or entities are needed, they should be described in a way that allows independent checking.

If the designer is part of the cause-and-effect natural (ie, material) world, the theory should be able to describe or predict relevant observable processes. If the designer is outside the material world, it might still use observable processes, but an account would be necessary of how such interaction would occur.

If the proposed processes of design and implementation are not observable, even indirectly, the existence of the designer would be purely a matter of faith. For thousands of years there has been speculation about what might exist beyond the observable world. No unequivocal answer has been found and there is no apparent way of finding one. No designer that was "too mysterious for human beings to describe" could be part of a scientific theory. So it is important for a scientific theory of ID to propose characteristics of the designer that are compatible with what is observed about organs and organisms, and also with the processes by which the design might be created and implemented.

With no attributes of the designer yet proposed, what can be learnt or suggested by looking at life forms in general? As an arbitrary preliminary attempt, some salient things we observe are:

This list suggest a designer with different perspectives and values from ours. While we might try to deduce what these may be, it provides neither refutation nor justification of intelligent design.

From this list and, dubiously, using human criteria, some possible conclusions could be that the designer:

Or there may be more than one designer and they are playing some competitive survival game, reminiscent of science fiction stories or computer games.

All this is pure speculation, suggesting how something might be gleaned, or postulated, about a designer. But it is hard to find anything in nature that might reveal the attributes mentioned earlier that a designer would need.

To prevail against evolution, ID should propose attributes and processes without contradicting accredited observations, and explain things that evolution cannot. The only serious postulated failing in the theory of evolution is the matter of complexity, claimed by proponents of ID. It will now be examined.

Too Complex to have Happened by Chance

The idea that evolution is "too complex to have happened by chance" raises three questions:


The word complex, like the word difficult, implies some relationship to human ability. Puzzles are difficult or complex when you don’t know the method of solution, but simple when you do.

Chaos theory has shown that many processes that seemed to behave in a very complex way can be described by a fairly simple equation. Cellular automata - computerised simulations of "reproduction" - demonstrate that complex forms can arise from simple beginnings, using a few simple rules for the survival of members of the present generation and production of the next. A fishing line can easily get into a very complex-looking tangle that takes a lot of unravelling. Fishing lines and mathematical figures are, of course, much simpler and contain far fewer components than living organisms. But they can come together into ever larger combinations by obeying just a few rules of nature.

Something may look complex when it has a lot of components. But as each one is examined and the interrelationships are understood, the whole may be explained. Many molecules have a very complex shape because the various forces acting within their component atoms push them into tangled contortions. The laws of nature produce complex forms everywhere, in ways that are explicable, even though they might require many steps.

A rough way of comparing complexities would be to compare the number of parts. A refinement would be to compare the number of different kinds of parts, and then the number of relationships and types of relationships between the parts. But when we marvel at living complexity, it is usually not these statistics that impress us but that the particular organ or organism performs so well.

Too Complex

A puzzle may be too complex for a four-year-old child but not for a ten-year-old, because spatial, numerical and other concepts develop as a child matures. A problem may be too complex to resolve without certain information. Many mathematical problems that were too complex to calculate without a computer have been solved using one.

These concepts of "too complex" relate to circumstances. So what circumstances make evolution of species impossibly complex?

Proponents of ID say that most organs and organisms could not be functional if certain significant parts were removed. They call this "irreducible complexity". They also claim that organs could not function in any form simpler than what now exists. The structures of biological organs are continually being investigated, categorised and recorded, and their operations better understood. They generally, and specifically the ones referred to as being irreducibly complex, are found to have simpler counterparts in present or extinct species. And the very first ones? They appear to have come from simple changes that brought new types of capabilities, as in the description, given earlier, of the development of eyes.

A similar claim is that, since all components of complex structures specifically complement each other, they must have been designed together. The evidence shows that biological components develop in step with each other.

An improved model of a designed artefact, for example, a motor vehicle, may incorporate a dramatically new version of any of its parts or a major rearrangement. In an evolutionary process such types of change are impossible, because no intermediate step will survive if it delivers an overall disadvantage. Therefore many organs with inherently inefficient or damage-prone features persist over long periods of time and across a range of similar species. This shows that they are stuck in an evolutionary rut rather than being the result of design. One example is in the eyes of mammals, including human, where the nerves carrying the signals from the retina to the brain are in front of the retina, partly blocking it from what it is viewing. Some unrelated species, such as cuttlefish, have eyes somewhat similar to mammalian eyes but which developed separately without this flaw, ie, the nerves are behind the retina. There are many other examples of evolutionary ruts.

But, accepting that some adaptations might have occurred through natural processes, could all the modifications required by evolution have really occurred by chance? To answer this we should examine the concept of chance.


To say something happened by chance means that either it was unexpected or we can’t tell precisely what caused it. The history of science and technology is replete with discoveries that occurred because something "went wrong", ie, happened by chance. Chance occurrences bring significant people together in all fields of life and continually affect the course of history.

Many significant things in most people’s lives happen by chance: their first meeting with their future life partner, the way they started in their "chosen" profession, or how they were the unlucky victim of some accident. Almost everyone can remember several trivial coincidences in their lives. Coincidences happen in great profusion, just through sheer probability. For example, if there are 23 people gathered together (for reasons that have nothing to do with birthdays) there is about a 50/50 chance that there will be at least one pair with the same birthday. Make it 30 people and at even money it’s worth betting on. When you understand a process you can see how such apparently unlikely coincidences may really be very probable.

Proponents of ID, who talk of "specified complexity", alleging a very high improbability of evolution, do not understand this. Their improbabilities relate to a process where all the components of a particular organ or organism somehow come together in the correct arrangement in one single step. This is the antithesis of evolution.

With large numbers of organisms continually taking in and converting food and energy in a changing and chemically reactive environment, very many significant interactions keep occurring, inducing inheritable mutations to very many individuals. Continual mutations to DNA make it very probable that succeeding generations will keep adapting to their environments. Indeed, the only way succeeding generations have continued to survive changes in their environment is by adapting via some process such as evolution.

The same kinds of mutation enable people to breed different strains of plants and animals. In different breeds of dogs, for example, selection of size and structure of the body, structure of the retina, innate inclination and ability to round up sheep or retrieve game, etc., are driven by the requirement to perform specific tasks rather than to survive specific environmental conditions.

The great range of environments on Earth, changing from place to place and from time to time continually provides opportunities for the diversifications to develop into new species. The prolific progeny of most species, each having to struggle to reach maturity, amplifies this process. Chance, therefore, makes evolution eminently feasible.

This doesn’t mean that speciation must have occurred through natural processes, but it discredits the argument that evolution is statistically unlikely. Indeed, to attempt to calculate the probability of any particular type of organism or organ developing in such lengthy, complex and unknowable circumstances would be futile.

Can intelligent Design stand up as a theory?

In the public debate about ID, much of the heat is the result of peoples’ hopes that a scientific theory will support their religious, philosophical or political beliefs. But no scientific theory - evolution, ID or anything else - should ever be considered as the final word. A theory is merely a tool - for explaining observations, for guiding and assisting further research and for the development of new technology. Sometimes evidence supporting a new theory is staring us in the face but is not recognised. Occasionally a new entity is discovered, eg, the nuclear forces during the twentieth century. Many scientific riddles await solution at this moment. But no new theory will be accepted as "correct" unless it is useful or reflects the evidence more logically than any other.

There seems to be no existing observation of nature that would put the theory of evolution in need of any replacement or revision, eg, the discovery of organisms that could not have resulted from evolution. Examples might be ones similar to existing species but with some organs radically different - like cats with non-mammalian eyes - or whose form and processes depended on something very different from DNA. No such evidence has yet been found.

This discussion has put both ID and evolution on trial, but it is an uneven situation. A refutation of ID would merely affirm the standing of evolution, which is supported by extensive evidence. But a refutation or weakening of evolution would not yet mean that ID must be true, because of the weakness of the current claims in its favour.

At this stage, ID is an incompletely-developed reaction to the theory of evolution. Its concept introduces an entity and types of processes that are unknown to science. To be a scientific theory it would need to propose testable processes that logically explain the diversity of species, and characteristics of the designer compatible with those processes. None appear to have been offered.

That is not to say that it would be impossible to develop a successful rigorous theory around the idea of intelligent design, but the difficulties introduced by the concept seem insurmountable.

This is the text or the talk given to the Atheist Society, Melbourne
on 8 August 2006 by Graeme Lindenmayer
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