Mar 27 2008

Is Intelligent Design Falsifiable?

Intelligent design (ID), according to the Discovery Institute, is defined as follows:

“Intelligent design holds that certain features of the universe and of living things are best explained by an intelligent cause, not an undirected process such as natural selection.”

The primary scientific criticism of ID is that it is not a legitimate scientific theory, but rather a transparent attempt at recasting religious faith (creationism) in scientific-sounding jargon. But ID lacks the minimal criteria to be considered science. ID proponents, of course, reject this argument because the entire purpose of ID is to masquerade creationism as a scientific theory.

Much of the discussion on this question focuses on the specific point of whether or not ID can be falsified – can it theoretically be proven false by scientific evidence. ID proponents say yes, scientists generally say no. While I agree that the answer is mostly no, the more precise answer is that it depends – it depends on exactly how ID is being formulated and practiced. I contend that in practice, ID proponents have rendered ID unfalsifiable while playing with semantics in order to pretend that it can be falsified.

In the most recent blog entry of the Discovery Institute, Jonathan Wells responds to Francis Collins on this very issue. Wells writes:

More surprising is the fact that Collins is here citing experimental evidence against a theory he maintains is unscientific because it is not open to experimental testing. In claiming that evidence from gene duplication disproves ID, Collins is demonstrating that ID can be tested with scientific evidence. Either ID is unscientific, in which case evidence is irrelevant; or evidence can be cited against it, in which case ID is scientific. Collins can’t have it both ways.

It is actually Wells who is trying to have it both ways – citing evidence against ID to demonstrate that it is falsifiable without acknowledging that it has been falsified. This is the game that they play. Pretending ID can be falsified, but then always keeping just out of reach of scientific evidence so that in practice it can never be falsified. There are actually several problems with ID that render it unscientific.

Asking the Wrong Question

As the definition given above indicates, ID is based upon a false dichotomy – that design in nature is necessarily intelligent and that evolution is an “undirected process” incapable of producing design. ID proponents have carefully crafted their premise – design = intelligence, evolution = random. Then all they have to do is show the appearance of design in nature and claim that ID is verified.

The fatal flaw in this strategy is that evolution is capable or producing design also, and it is not a random process. Natural selection is the non-random survival of organisms based upon their inherited traits. Mutation and variation is random, and the long-term path of evolutionary change is best described as chaos, but natural selection allows for the non-random accumulation of favorable changes.

So the ID proponents are asking the wrong question – always a fatal problem in science. The question is not whether or not there is design in nature, but what is the nature of that design. Evolution is a bottom-up process whereby design and complexity emerge out of blind but non-random processes. “Intelligent” design, by contrast, is a top down process where the final result is known ahead of time by the designer and is achieved with purpose.

There are many analogies we can draw to illuminate this difference. For example, a city that grew over decades without any central planning, but based upon the decisions and actions of individuals acting in their own interest is like an evolved city. An ID city, however, is one planned and mapped out ahead of time, by a committee, corporation, or some other body. In the evolved city there will still be design – streets and utilities will follow residences and business, for example. Shops will tend to pop up and survive to meet the demand. But it will be messy, with lots of redundancy, with abandoned buildings where neighborhoods collapsed or business failed. Streets would likely not be optimally arranged. A planned city, however, would look vastly different – more clean, purposeful, and direct. The streets would be laid out in a deliberate way – one that could not have emerged spontaneously with use.

The difference between evolved and top-down designed life would be even more stark. Buildings and entire city sections can be torn down and rebuilt – so some top-down design can always be imposed later. But biological systems are far more constrained. Bottom-up evolutionary systems can only work with the raw material at hand. They cannot start from scratch, develop new organs or limbs wholesale from nothing, or completely eliminate unneeded bits of anatomy.

If we ask the correct question – does life display bottom-up or top-down design, the answer is obvious to anyone with sufficient knowledge of biology and an unbiased mind. Life is overwhelmed by bottom-up design, from the vestigial eyes of cave salamanders to the bits of viral DNA junking up our genome. But none of this can falsify ID because they are asking the wrong question.

Common Descent

It is important to recognize in any such discussion that evolutionary theory actually has multiple components – the fact that life’s diversity arose through evolutionary branching descent over time, the specific mechanism(s) of evolution, and the particular pathway of evolution taken by specific branches of the tree of life. One important line of evidence for the first claim of evolution – that life arose through branching descent – are the many biological similarities among various species that not only demonstrate common descent, but a branching pattern of descent predicted by evolution.

In the quote above Collins is referring to evidence from gene duplication – that over time one gene can become duplicated as a mistake of replication. Descendants will therefore have two copies of a gene instead of one. The duplicate copy is therefore free to change over time through mutations, essentially free to experiment with variations of function, because the original gene copy is able to carry out the original function of the gene. The duplicate gene may therefore hit upon a new function that helps the original gene carry out its purpose, or perhaps it may become co-opted for an entirely different purpose.

Biologists can examine the sequence of base pairs in genes to map our their relationships with other genes, and in that way can build a detailed map of which genes evolved from which other genes. What we find when we compare such maps among species is that they fit into a nice pattern of branching common descent. There are multiple other independent lines of evidence that also demonstrate not only branching descent, but a reasonable overlap – the different lines of evidence generally agree about which species evolved into what when.

These lines of evidence could have completely falsified evolution. It is possible, for example, that we could have found patterns of gene variation that were incompatible with the theory of common descent. If we bring this back to the question of whether or not ID is falsifiable we have to ask – is there a pattern of gene variation we could have found that could potentially falsify ID? The answer, apparently, is no. At least I am not aware of any ID proponent making such a prediction that was open to falsification.

But this is also where we get into the “it depends” answer. As I stated above, evolution have various components, only one of which is common descent. Some ID proponents, like Michael Behe, actually accept the fact of common descent. They think that life did change over time through branching descent. They just don’t think this process was due to natural selection acting on variation. They think it was guided top-down by an intelligent designer. So evidence of common descent is not evidence against this form of ID.

What about those who do not accept common descent? Those who, like young earth creationists, think that life was created more complete, that the “designer” did not spend millions of years making slow changes over time, but poofed life into existence pretty-much as it is. Evidence for common descent does falsify such claims.

Or does it? In theory, yes it does. And those like Wells are now using this to argue that ID is science because it can be falsified. But in practice, it does not, because ID proponents and creationists who reject common descent make the argument that the intelligent designer could have chosen, for their own unfathomable reasons, to make life so that it has the appearance of branching descent. The “God can make life to look like whatever he wants” defense renders the beliefs of anyone who makes it unfalsifiable. So either way this line of argument does not make ID falsifiable science.

Irreducible Complexity

This is the primary line of argument for the falsifiability of ID – that we can look for design in biological nature by looking for structures and biochemical pathways that are irreducibly complex, meaning that they could not function if they were any simpler. This argument also has many flaws.

The biggest problem is that, once again, this argument is based upon a false premise – but one that was chose to achieve the desired result. The premise is that if a structure could not function for its current purpose if it were any simpler – if any complexity were removed – then such a structure could not have evolved because it could not have passed through simpler forms to get to its irreducibly complex state, because evolution requires that in order to be selected for a structure would have to provide an adaptive advantage every step of the way.

This superficially sounds reasonable, but it has been shown to be a false premise and yet the ID crowd will not abandon it. Specifically, the premise ignores the possibility that an irreducibly complex structure could have evolved from a simpler structure that served a different purpose. So, for example, the bacterial flagellum could have evolved from a simpler tube that could not move but was used to inject substances into another cell. This simple syringe could have been an evolutionary stepping stone to the more complex flagellum – and in fact evidence now supports this hypothesis.

In practice the notion of irreducible complexity contains two strategies – the first is to argue that a biological entity could not be simpler even in theory. But as discussed above this strategy is based upon a false premise and is therefore not valid. So ID proponents fall back to their second strategy – arguing that evolutionists have not fleshed out the actual evolutionary history of an apparently irreducibly complex structure or pathway. But this second strategy is nothing more than an argument from ignorance. It relies upon our current knowledge and assume that currently unknown equals unknowable, and further than unknowable means impossible – impossible for evolution, therefore we need to invoke an intelligent designer.

An argument from ignorance – basing a conclusion on what is not known – is always a weak argument, because it does not require any positive evidence for a theory, it’s just knocking down a competing theory. Also, what has happened since Behe made his initial claims for irreducible complexity is that scientific progress has continued, and many of the holes in current knowledge that Behe relied upon have been filled in, like the bacterial flagellum example above.

What implications does this have for the question of whether or not ID is falsifiable? Well, it establishes that specific claims used to support ID are falsifiable. We have now falsified the claim that the bacterial flagellum has no simpler evolutionary antecedents. Wells and others use this to say that ID is therefore falsifiable. But once again, in practice it isn’t, as is evidenced by the very fact that Wells, Behe and others have not abandoned ID because the flagellum argument was proven wrong. This is because when one argument falls, they simply migrate to another. They even state that in order to falsify ID evolutionary scientists would have to flesh out the complete evolutionary history of every biological component. This, of course, is an impossible and absurd standard.

What they are admitting, without meaning to, is that ID is ultimately a “god of the gaps” belief, and the only way to falsify it is to close every single last gap.

The False Dichotomy

The notion of ID falsifiability also has a deeper logical problem – that ID is defined entirely but what it isn’t – namely evolution. ID is based upon the claim that evolution cannot explain life. This is a false claim, as I have pointed out above, but even if true it would not be evidence for ID. So ID proponents spend their time trying unsuccessfully to poke holes in evolutionary theory, or pointing out the current gaps in our knowledge (while ignoring the fact that this is a rapidly moving target), all the time pretending that is somehow evidence for ID, when it isn’t.

I already discussed that their strategy is to equate all design with intelligent design, ignoring the fact that natural selection acting upon random mutation is a cumulative process capable of generating bottom-up design. The real question is whether or not the design we see in biology looks top-down intelligently designed or bottom-up evolutionarily designed. If ID proponents had an actual theory they should be able to say something about the features of intelligently designed life (predict what we should find) – and these features can be looked for to see if their design predictions pan out. So far they have not been able to do this.

Their answer to this is irreducible complexity, but as I explained this doesn’t cut it.

What they will not do is make any statements about the intelligent designer. What marks would such an intelligence leave upon creation? No one appears to know. When pressed they often play the “it’s a mystery” card. How can we possibly fathom the intelligence necessary to design and create life? Evolution does make many specific predictions about what evolved life should look like – predictions that have been validated. Evolution’s successful positive predictions are a problem for ID, but they deal with them the same way, by essentially arguing that the designer could have arbitrarily and inexplicably decided to make life look as if it evolved.


While there are many complexities to the question, complexities exploited by ID proponents to create confusion, the answer to the question asked in the title of this entry is that ID is not falsifiable – at least not how it is promoted by ID proponents.

The challenge that remains open for the ID community is to state a specific prediction about what positive evidence should be present if life were top-down intelligently designed. They cannot do this. Their predictions are all negative – what evolutionary theory won’t be able to do. And worse their negative predictions are all constantly changing in order to keep one step ahead of the advance of evolutionary science (making ID functionally a god-of-the-gaps argument).

Perhaps the Discovery Institute (if they were overcome by an uncharacteristic spasm of intellectual honesty) should change the definition of ID to :

“Intelligent design holds that certain features of the universe and of living things were caused by an intelligent agent who, for reasons we do not care to get into, chose to make the world look exactly as if it were the product of random variation and natural selection.”

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