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| Intelligent Design Debate and the Rehabilitation of Analogical Knowledge
The Intelligent Design theory is based on a valid form of reasoning and is essential to the proper understanding of nature, but it is not a theory in natural science.
1. Is there a limit to knowledge attainable by natural science?
The Intelligent Design theory makes two assertions:
1. The Darwinian mechanism is unable to explain the evolution of central biological systems in nature.
2. Only an intelligent cause can explain the evolution of such systems.
As far as I can see, only the first of these assertions is amenable to discussion on the terms of natural science.
For a philosopher without a background in natural science, it can be very difficult properly to assess debates in this area; but to the extent that I have been able to follow the discussion revolving around the first assertion, it seems to me that Intelligent Design theory (hereafter ID theory) presents strong arguments.
The core argument in the critique of Darwinism is the claim that nature encompasses systems that are irreducibly complex. Irreducibly complex systems cannot emerge as a result of serial cumulative improvements in a system. The existence of such systems in nature therefore raises a problem for the Darwinian explanation, since the latter explains evolution in nature by appeal to the notion of the gradual improvement of systems.
It is important to note that there is one kind of evolution found in nature for which ID theorists such as Michael Behe do not deny the Darwinian mechanism's ability to account - microevolution. Nor do they claim that it is impossible that an irreducibly complex system should arise by virtue of natural selection and random mutations. Behe distinguishes between direct evolutionary pathways and indirect pathways. While the notion of direct pathways is dismissed out of court that of indirect pathways is not. Behe argues, however, that an indirect pathway is improbable. Significantly, then, this concession shows that the ID theorists do not blanketly reject every Darwinian explanation.
The Darwinian defence typically comprises two arguments. One involves the extrapolation of provable microevolution to macroevolution. This argument appeals to the extraordinary temporal span of 3-4 billion years through which the evolution of living organisms has progressed and the scope for complication such an expanse involves. Another argument involves the identification of possible indirect pathways that Behe and others have overlooked. Kenneth Miller points out that the functions of the components of a system are subject to change over the course of evolution, which feature may explain how a complex system gradually came to be. And Allan Orr has pointed out that functions which begin merely as an advantage to the organism may later become indispensable to it, which circumstance may explain the emergence of complex systems.
The possibility of indirect pathways is not the sort of consideration that will settle the scientific issue. Both sides agree that indirect pathways are a logical possibility. No clinching argument would appear to be forthcoming.
The ID theorists' defence against the Darwinian critique is to point out that the latter's putative explanations of irreducibly complex systems by appeal to indirect pathways are too speculative to qualify as natural science. Rather, they are speculative conjectures about how evolution might have taken place through natural selection and random mutations. Now, the ID theorists' attack on Darwinism on this point proceeds entirely on the premises of natural science, invoking the very criteria that natural science itself has defined. Rather than seeking to go beyond science, they adhere more rigorously to its canons than do the Darwinists. Loose speculation and an appeal to fabulously felicitous random mutations do not amount to valid scientific explanation.
On my reading of the discussion, Michael Behe, William Dembski and others succeed in offering an assessment of the Darwinian defence that is predicated on the premises of natural science itself. They reach the verdict that the Darwinists' defence consists of speculative and scientifically unsound explanations. Indeed, they bolster their case further by showing that there are features of Darwinian theories that are improbable according to probability theory. The strength of an argument based on probabilistic calculations is of course its mathematical rigour.
It must be concluded that it is intrinsic to this discussion that it resist closure. Both sides party to it are natural scientists, and the discussion proceeds on the terms laid down by natural science itself. Yet there is no agreement; the opposite is the case. It is difficult to judge who is right. The Darwinists are always going to be able to say that a Darwinian explanation is not impossible, and that sometimes speculative conjectures are required if science is to advance. The future, they maintain, will surely vindicate Darwinism. We know that natural science progresses and is forever broadening its explanatory scope. At some point in the future, we will be able to explain the evolution of irreducibly complex systems in a way that satisfies the criteria of natural science. The critics of Darwinism, for their part, will reply that the relevant hypotheses remain either outright improbable or else wildly speculative, and that gesturing towards the future is no argument at all. Nobody knows the future. It may prove Darwinism to be right, but it may equally well show that its critics are.
There is a real risk that this discussion will go on forever. New data is likely to be forthcoming. The Darwinists are going to interpret them as confirming Darwinism, and its critics will be able to point to the speculative and improbable elements in the Darwinian hypotheses. Is it conceivable, they will say, that the evolution of something as complex as, for instance, the human stem-cell, which contains within it the potential for all other types of human cells, will ever be scientifically explicable by reference a pair of factors as simple as natural selection and random mutation? Or that the evolution of anything exhibiting such an astonishing degree of complexity should be explicable in terms of self-organization?
Since the issue is irresoluble by appeal to natural science, I believe we have no choice but to be agnostic about which side is right. And I would venture the prediction that that is how the situation is set to remain. Both parties to the debate find support for their positions in natural science. The standard criticisms of Darwinism have a pedigree that dates back to its first beginnings. What is new about the latest ID challenge to Darwinism is that it is strictly scientific - indeed, as scientific as Darwinism itself purports to be. Darwinism is no longer the only party to the dispute able to invoke natural science to validate its claims; its critics do so too.
I think that we are forced to conclude that so far as natural science goes, the debate between Darwinism and its critics reveals that we simply have no fix on how irreducibly complex systems have evolved in nature. Participants to the discussion should be prepared to make this concession: that We simply don't know.
The philosopher Immanuel Kant shared the opinion of today's ID theorists. He writes:
"[I]t is absurd for men...to hope that another Newton may some day arise, to make intelligible to us even the genesis of but a blade of grass from natural laws that no design has ordered. Such insight we must absolutely deny to mankind" (i).
It may be objected that Kant could have had no inkling of Darwin's discoveries. Darwinists will claim that "the Newton of the blade of grass" has arrived, and Darwin is his name. It was impossible for Kant to foresee that a mode of explanation would emerge that involves chance and the combination of necessity and chance as essential factors in the scientific explanation of nature. However, Dembski's analysis of what a stochastic process is able to explainii shows that Kant's assertion remains irrefragable to this day.
2. Both Darwinists and ID theorists overstep the bounds of natural science.
Neither Darwinists nor ID theorists make the concession referred to above. Both sides press further. But I would contend that assertions that ramify beyond a confession of agnosticism as regards the evolution of irreducibly complex systems are plainly not natural science.
Darwinists go beyond the evidence in two ways. Firstly, they claim that at some future point the Darwinian mechanism will be capable of accounting for the emergence of irreducibly complex systems. Secondly, they claim that any theory attributing to an intelligent cause the emergence of irreducibly complex systems is a non-starter. Such assertions have no foundation in natural science but are the expressions hope or conviction. They are indicative of the trust or conviction that such is the explanatory power of natural science that it will some day prove capable of explaining all natural phenomena. Add to this the conviction that ID theory is impossible and we can further define Darwinism as the naturalistic belief to the effect that all the phenomena existent in nature are explainable in terms of unintelligent, immanent causes. It surely hardly needs arguing that the hope, trust and conviction to the effect that that natural science is in principle capable of explaining the totality of natural phenomena is not itself a piece of science. It adds nothing to the explanation of empirical observations. It is a belief predicated on the success that natural science has enjoyed to date. Since natural science has proved capable of explaining increasingly many natural phenomena, we come to believe that it will ultimately be able to explain all phenomena. The result of induction, this theory is susceptible to Karl Popper's falsification test. Since natural science has proved capable of explaining some natural phenomena, it must in principle be capable of explaining all natural phenomena. The theory is falsified if it is possible to identify just one phenomenon in nature - e.g. an irreducibly complex system - which natural science cannot explain. There are grounds, then, for thinking that the Darwinian argument errs by overextending the concept of a natural science theory. I think it more reasonable to say that the trust and conviction that underpin the claim are not part of a scientific theory at all but constitute a metaphysical belief with no real foundation in natural science - indeed, the belief is a naturalistic religious belief.
The ID theorists match the Darwinists in their reluctance to embrace agnosticism in respect of the question of how irreducibly complex systems evolved in nature. They too go further and claim that the emergence of irreducibly complex systems can indeed be explained by an intelligent cause. They do not see this claim as some sort of leap of faith. It is not a conviction based on belief in a divine creator. It is a claim underpinned by the findings of natural science.
Now it is right to say that it is not a claim which presupposes a belief in a divine creator, but nor does it qualify as a scientific claim. The claim is not predicated on some metaphysical tenet; it is based on empirical data and on a rational interpretation of these data. The claim looks as though it fits into a natural science context because it is based on empirical data - the demonstration of a system's being irreducibly complex is essentially empirical in character. But what sets this claim apart from the body of knowledge we call natural science is the species of reasoning that invests it with its content. The mode of cognition in play is analogical cognition. We engage in analogical reasoning whenever we grasp the nature of something in virtue of its similarity to something with which we are already familiar. Given some unfamiliar X, we are able to get a grip on what X is because it resembles something already known. We frequently acquire knowledge in this way. Natural science, by contrast, proceeds not on the basis of analogical reasoning but by establishing causal relationships. In natural science, we get to understand a phenomenon by establishing its cause. There is a significant difference between the two modes of cognition. But more on that later.
For the moment, I just want to point out that the ID theory's claim to the effect that the evolution of irreducibly complex systems results from an intelligent cause reposes on an argument by analogy. We recognize that an irreducibly complex system bears a strong resemblance to a man-made machine. The two phenomena share certain essential features. Both a watch and an irreducibly complex biological system exhibit parts that enter into an integrated whole, which performs a specific function. The parts of a watch are mutually adjusted so that their interaction performs the function of telling the time. By the same token, the parts of a cilie interact as elements of a well-integrated whole to fulfil the function of enabling the organism to swim. However, this conception of the constitution of an irreducibly complex system occurring in nature is not a scientific one. Our grasp of an irreducibly complex system is not the result of understanding what causes it. Our grasp of what it is derives from what it resembles. Reasoning from analogy, then, enables us to get a grip on what an irreducibly complex system essentially is. It might be alleged that the analogical inference paves the way for its scientific counterpart since on its basis we are able to infer that the irreducibly complex system has an intelligent cause. Surely, it might be argued, once causal inferences are in play, what we're dealing with is natural science. So ID theory emerges as scientific after all. But no, for it is crucial to the argument that its conclusion to the effect that the irreducibly complex system is caused by an intelligent cause is reached by indirect means. Analogical reasoning does all the work. The inference has it that because a man-made machine has an intelligent cause, an irreducibly complex system must also have an intelligent cause. But this inference rests on a piece of analogical reasoning. Plainly, then, the inference is not intrinsically causal but analogical.
ID theory may appear to carry the credentials of natural science because it ends up by explaining a natural phenomenon by reference to a cause. But this is how it looks only if that the intervening analogical reasoning is discounted. However, the analogical argument is no mere sideshow, it is crucial. It implies a categorical shift in what concerns the acquisition of knowledge. Anyone concerned to analyse and evaluate ID theory needs to sharpen the focus on analogical reasoning.
When ID theory moves from criticizing Darwinism on the premises of natural science to drawing the inference that there must be an intelligent cause, it performs quite a leap. This emerges clearly from a reading of books and articles about ID theory such as, say, Michael Behe's Darwin,s Black Box or Stephen Meyer's articles. The greater part of Behe's book is devoted to a critique of Darwinism that proceeds on the premises of natural science, offering a wealth of scientific detail. The claim that irreducibly complex systems can only be explained by an intelligent cause is addressed with striking brevity. Indeed, the topic is dealt with in a few sentences: Irreducibly complex systems look like man-made machines. Man-made machines are the work of human intelligence. Consequently, irreducibly complex systems owe their existence to an intelligence. Detailed explanation is largely absent. The whole tenor of the writing shifts. This leaves most Darwinists bemused: is that all that these theorists have to say?
3. ID theorists erroneously consider ID theory to be a natural science theory.
Dembski writes:
"In response to the question, how did life originate and develop?, what is wrong with saying we don't know? ... As philosopher of science Thomas Kuhn and Larry Laudan have pointed out, for scientific paradigms to shift, there has to be a new paradigm ready and waiting. You cannot shift into a vacuum. Napoleon III put it this way: 'One never really destroys a thing till one has replaced' (ii)"(iii).
This statement is an expression of the view that ID theory is a natural science theory, destined to replace Darwinism as the appropriate natural science explanation. I think Dembski is wrong on this head.
It is obvious that why ID theorists want to propound ID theory as a natural science theory. The term "natural science" is prestigious. In our contemporary cultural climate, to say that a theory is not scientific is tantamount to saying that it is subjective and arbitrary. Clarity would be served, however, by ID theorists' desisting from calling their theory natural science. If they continue to insist on doing so, they risk losing the argument to the Darwinists. For it is readily shown that ID theory contributes very little real natural science. Behe's book, for instance, makes no real contribution to biochemistry. Rather, it represents an interpretation of biochemical research, and the chief contribution it makes is to analogical reasoning, science theory and philosophy. In the same spirit, I had a mathematician read Dembski's book The Design Inference, and his conclusion was that the book contributes fairly little to mathematics, but that it might prove fertile in other ways. Sam Northshield writes in The American Mathematical Monthly Review: "Not a textbook but a philosophical tract about when one can infer design behind events of very small probability. Thought provoking, fun to read, full of interesting examples"(iv). Dembski's contribution adds first and foremost, then, to the articulation of analogical reasoning and to philosophy. If ID theorists insist that what they are offering is a contribution to natural science, I fear they'll undermine their own cause, with their theory going the way of so many other attacks on Darwinism since its emergence, simply on account of a failure to attend to the difference between knowledge of causal relations and analogical reasoning. ID theory's signing itself into oblivion would be very regrettable, for its time has come.
If ID theorists overextend natural science theory by insisting on ID theory's scientific credentials, it becomes almost impossible to repudiate the charge persistently levelled at it by Darwinists to the effect that ID theory is a "God of the gaps" theory: the theory fills a gap that natural science cannot fill. Or to repudiate the criticism that ID theory is an "argument from ignorance". I think the answer to these points of criticism is to say that insofar as ID theory steps beyond the realm of natural science, it does so in virtue of being a non-scientific mode of cognition. The way to respond to the "God of the gaps" argument is to deny that ID theory is part of natural science. And the answer to the "argument from ignorance" critique is to maintain that the design inference is founded, not on ignorance, but on analogical reasoning.
ID theorists are trying to establish an ID theory scientific research program, but not, to my knowledge, with significant success so far. One of the claims for which they seek to argue is that "reverse-engineering" constitutes a positive contribution to natural science. "Intelligent design's positive contribution to science is to reverse engineer objects shown to be designed" (v). But does "reverse-engineering" really qualify as a natural science input to biology? We need to draw a distinction between theories that properly belong to the sphere of natural science and those which serve as purely heuristic ideas. I would contend that ID theory is a heuristic idea that is indispensable to biology. As a heuristic idea, it enables us to attain an essential grasp of what an organism is, namely, a specified complex system. The actual natural science contribution concerns the mapping out of the immanent causal relations that inform the system. Nothing should prevent a Darwinist from acknowledging ID theory's status as a heuristic idea; indeed, it is questionable whether he or she can so much as avoid doing so.
Dembski often stresses the importance of investing ID theory with the status of natural science. The difference between ID theories of the past and their present-day counterparts is that contemporary ID theory is or ought to be scientific, while the ID theory of the past amounted to mere philosophical speculation. I find this contention misguided. ID theory should not be propounded as having the status of natural science, but as what it is - argument by analogy.
ID theory should not replace scientific theories. Darwinism and theories of self-organization are the only natural science theories that we have about the evolution of nature.
I will refrain from going into detail here about theories of self-organization since they are without implications for any of the points I am arguing in this essay, The discussion about theories of self-organization parallels that concerning Darwinism. Theories of self-organization can explain the emergence of systems which exhibit a fair degree of complexity, but can they explain the emergence of enormously complex biological systems? On this point, I refer the reader to Behe's discussion with Shanks and Joplin(vi). Behe admits that theories of self-organization are able to explain the emergence of systems that exhibit some degree of complexity, but can these theories explain the emergence of highly complex systems? Behe distinguishes between simple interactive systems and irreducibly complex systems, but he admits that it can be difficult to make the distinction with any precision. The proponents of self-organization theories claim that these theories will some day be able to explain the emergence of highly complex systems. ID theorists point out that self-organization theorists have enjoyed little success until now and remain sceptical of the hopes invested in their project. Will that discussion also prove to be an interminable one?
To this point, I have not offered any definition of natural science. This is because I agree with Larry Laudan that it is impossible to define natural science in the abstract(vii). However I shall now venture what I would call a contextual definition, which is to say a definition that is restricted to a particular context of discussion: I shall offer a definition of natural science as it pertains to the context of ID theory and theology. Against this contextual background, I would define natural science as the endeavour to explain the phenomena of nature in terms of cosmically immanent causes. As opposed to the analogical mode characteristic of ID theory, natural science is a causal mode of cognition. And, as opposed to theology, which may properly appeal to a transcendent cause explanatory of the natural world, the causes to which natural science refers are strictly immanent. I do not believe anyone would sanction calling an explanation that invoked a transcendent cause scientific. Over its history, natural science has defined itself as a mode of systematic inquiry which confines itself to immanent causes. The project that is natural science is one whose defining task is to investigate how far we may extend the scope of our knowledge by explaining nature in terms of immanent causes. Dembski often argues that the immanent/transcendent causal disjunction is false, because appeal to intelligent causes has a legitimate place in natural science. The problem, however, is that explanations which refer to intelligent causes are based on arguments from analogy, which, ipso facto, do not qualify as natural science. Consequently, intelligent causes have no place in natural science. Dembski also points to the fact that in other fields of rational inquiry, intelligent causes are entirely licit - in archaeology, forensic science, etc. My answer to that is that my contextual definition aims solely to capture the meaning of natural science, and does not apply to studies in the humanities, theology, etc.
The Darwinian theories and self-organization theories are the only natural science theories we currently have about the evolution of nature, and the question here is how far these theories take us. ID theory should seek neither to halt their progress nor to replace them. Rather, it should make a contribution to them. Indeed, this is precisely what it does when it seeks critically to estimate their scope. Behe's book is an input to Darwinian theory, because Behe is himself a natural scientist and criticises the Darwinian theory on the premises of natural science.
The discussion between Darwinists and ID theorists is often virulent and acrimonious. Richard Wein writes for instance:
"Some readers may dislike the frankly contemptuous tone that I have adopted toward Dembski's work. Critics of Intelligent Design pseudoscience are faced with a dilemma. If they discuss it in polite, academic terms, the Intelligent Design propagandists use this as evidence that their arguments are receiving serious attention from scholars, suggesting this implies there must be some merit in their arguments. If critics simply ignore Intelligent Design arguments, the propagandists imply this is because critics cannot answer them. My solution to this dilemma is to thoroughly refute the arguments, while making it clear that I do so without according those arguments any respect at all"(viii).
It is my impression is that the reason why the discussion so often becomes vitriolic is that while it is ostensibly about science, what is really at issue is metaphysics and religion. The Darwinists are not just defending scientific results and theories, but also the quasi-religious belief that the Darwinian mechanism is able to explain all biological phenomena. Similarly, ID theorists are not just attacking certain scientific theories, but are attacking Darwinism as a naturalistic metaphysics while defending that informing ID theory. The discussion often quickly becomes a war on Darwinism or a war on ID theory.
I believe we are able to avoid this distortion of the debate, which renders it profitless, by making it clear that what we are dealing with are two separate discussions. One discussion concerns the explanatory scope of the Darwinian mechanism. Darwinists don't have to panic and turn hostile because they have to admit that so far we haven't explained a great deal. That circumstance doesn't disqualify the theory. And nor do ID theorists have to enfranchise their theory as natural science. Its having another status doesn't disqualify it. ID theory should not be introduced into education as the proper candidate to replace Darwinian theory or as an alternative theory of natural science. It should be introduced as a theory that reinstates analogical reasoning - as a piece of science theory and philosophy. Both sides have to address the issue of how much the Darwinian theory or self-organization theories are capable of explaining. Both sides have to address the issue of the validity of analogical reasoning. There is no reason why these two problems should not be discussed equably and with appeal to objective arguments.
I also think that it is important to keep the cultural and political agendas out of the scientific and philosophical discussion. The findings of gallop polls are totally irrelevant here. The scientific and philosophical discussion should proceed on scientific and philosophical premises, just as the cultural and political debates should be pursued on their own terms.
4. ID theory and Darwinism qua metaphysical beliefs.
ID theory should not replace Darwinism as a theory in natural science; it should replace Darwinism as a metaphysical belief. I believe this to be the claim that goes to the heart of what ID theory is essentially about. The thrust of ID theory is to challenge naturalism. But the effectiveness of this challenge does not depend on the formulation of ID theory as a theory in natural science. The problem with Darwinism is that it refuses to acknowledge its inability to explain how irreducibly complex systems have evolved in nature. It seeks to finesse away its ignorance by proffering what is in effect an article of naturalistic faith. It is this naturalistic doctrine that ID theory should seek to replace.
What needs addressing in the discussion between Darwinism and the ID theory is which of the two theories is the better founded. The crucial question, then, is what is better founded, the Darwinian belief in the potential reach of the natural sciences, or the theory that the emergence of irreducibly complex systems is properly attributable to an intelligent cause?
On my assessment, ID theory is the better-founded option, because while the Darwinian belief is purely conjectural, ID theory is the expression of a piece of intuitively compelling rational knowledge. ID theory is not based on an arbitrary belief to which we may or may not decide to subscribe. It is the expression of a cognition whose compelling character is universally recognized. It is based on empirical data and on an analogical interpretation of them. The crucial question is whether the knowledge purportedly acquired through analogical reasoning is indeed valid knowledge or whether it is merely a subjective supposition, a projection, or the like.
Analogical reasoning has been the target of vigorous criticism in the history of philosophy. David Hume's strictures in particular are well known and have exerted considerable influence on the subsequent evaluation of this mode of cognition. In my view, Hume's criticism overshoots its aim. Hume shows that analogical reasoning is weaker than a deductive proof. He is right about that. Analogical cognition is not as certain as a deductive proof and nor does it match the findings of the exact sciences. If we are able to observe that a given enzyme triggers a particular process we are possessed of more secure knowledge about the cause of this process than when we surmise that an intelligent agent has contrived the existence of a cell on the grounds of the cell's resemblance to a man-made machine. But the mere fact that analogical reasoning does not yield results as certain as a deductive proof or the facts established by the exact sciences does not disqualify it as a valid mode of cognition. So to disqualify it would be tantamount to claiming that scientific knowledge stands as the norm for all valid knowledge.
In response to Hume's criticism, Dembski has argued that the analogy between an irreducibly complex system and a man-made machine is far stronger than the forms of analogy refuted by Hume(ix). This is an important argument.
Dembski has also pointed out that analogical reasoning is widely practised in the humanities. If the archaeologist finds a stone bearing cuts that present a pattern, he or she will conclude that the cuts do not result from the operation of natural laws or chance, and will go on to infer by analogy that it is a man-made axe. It is the product of human intelligence. The analogical mode of cognition is routinely practised in several of the human sciences and regarded as valid.
In his The Design Inference, Dembski seeks to strengthen the analogical mode of cognition by formalising the logic behind it. This too constitutes an important defence. The defence of the analogical mode of cognition by giving it a sharper articulation does not invest it with certainty. It is not a mathematical proof. Even if an analogy is very strong, it cannot lay claim to certainty. And even if the analogical approach is routinely practised in the human sciences, we cannot simply assume that it is equally applicable to natural phenomena. It is one thing to infer from an unfamiliar item displaying irreducibly complex features that it was brought into being by a human intelligence; it is quite another to infer from a natural phenomenon displaying irreducibly complex features that an intelligent agent caused it, because no such intelligence in incarnate form exists. We are on firmer ground when conducting analogical reasoning in the human sciences than when applying it to the natural world. None of this allows us to infer, however, that analogical reasoning is invalid as applied to natural phenomena.
The most important argument for the validity of analogical reasoning arguably comes from phenomenological philosophy, which has evolved since the beginning of the 20th century on the European continent. Phenomenological studies have revealed that analogical reasoning is fundamental to our apprehension of the world. The German philosopher Hans Lipps, in particular, has contributed to this discovery. His phenomenological analysis shows that analogical reasoning is both universal and intrinsic to our acquisition of knowledge(x). As the phenomenological analysis of everyday language shows, analogical thinking is no mere option.
When we are struck by the fact that an irreducibly complex system resembles a man-made machine this is no subjective arbitrary observation but a non-optional shared cognition. Everyone - including the Darwinist - perceives irreducibly complex systems in this way, not just ID theorists. Without thi |
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