In two comments attached to his latest post over at Sandwalk, Professor Larry Moran argues that even a very unlikely naturalistic scenario would be a better explanation of irreducible complexity than a vague Intelligent Design hypothesis. Taken to its logical conclusion, Moran’s argument implies a paradoxical result (which I’ll refer to as Torley’s paradox): that for any specified pattern which we find in Nature, no matter how complex it may turn out to be, any naturalistic explanation of that pattern which appeals to specific processes – even astronomically unlikely ones – will always be superior to an explanation which invokes Intelligent Design in purely general terms (“Some intelligent being produced this pattern”). As we’ll see, the reason why Moran’s argument generates this odd result is that he confuses possibility with capability. (I should point out that when I use the term “naturalistic” in this post, I am not intending to contrast “natural” explanations with supernatural ones, but with artificial, or intelligently guided ones. Obviously, an intelligent designer need not always be a Deity.)
(Note to readers: I don’t like to claim credit for ideas which other people have already had, so if any reader can alert me to a writer who has previously drawn attention to the paradox I discuss below, then I will gladly rename it in their honor.)
Getting Behe wrong
In his latest post, Professor Moran reports on a 2011 paper by J. Lukeš, J.M. Archibald, P.J. Keeling, W.F. Doolittle, and M.W. Gray, titled, “How a neutral evolutionary ratchet can build cellular complexity” (International Union of Biochemistry and Molecular Biology (IUBMB) Life 63: 528-537). The authors summarize their paper as follows:
Complex cellular machines and processes are commonly believed to be products of selection, and it is typically understood to be the job of evolutionary biologists to show how selective advantage can account for each step in their origin and subsequent growth in complexity. Here, we describe how complex machines might instead evolve in the absence of positive selection through a process of “presuppression,” first termed constructive neutral evolution (CNE) more than a decade ago.If an autonomously functioning cellular component acquires mutations that make it dependent for function on another, pre-existing component or process, and if there are multiple ways in which such dependence may arise, then dependence inevitably will arise and reversal to independence is unlikely. Thus, CNE is a unidirectional evolutionary ratchet leading to complexity, if complexity is equated with the number of components or steps necessary to carry out a cellular process. CNE can explain ‘‘functions’’ that seem to make little sense in terms of cellular economy, like RNA editing or splicing, but it may also contribute to the complexity of machines with clear benefit to the cell, like the ribosome, and to organismal complexity over-all. We suggest that CNE-based evolutionary scenarios are in these and other cases less forced than the selectionist or adaptationist narratives that are generally told.
Commenting on this research, Professor Moran writes:
This is a perfectly reasonable scenario for the evolution of irreducible complexity. Anyone who claims that the very existence of irreducibly complexity means that a structure could not have evolved is wrong…
All that’s required is that evolutionary biologists propose a reasonable explanation making it possible for such structures to evolve naturally in a world where gods play no role in evolution. That has been done. The idea that irreducibly complex structures are impossible to evolve has been falsified.
When a reader named Bilbo commented that Professor Michael Behe had already responded to the paper by Lukeš et al., Professor Moran wrote a comment of his own in reply, in which he misrepresented Behe’s position, while putting forward a fallacious argument against Intelligent Design (emphases mine – VJT):
Behe parrots the standard creationist objections to anything they don’t like. He demands evidence and calculations. He claims that the scenario seems impossible (to him).
He misses the point. It’s a possible scenario for the evolution of an irreducibly complex structure. Even if it’s very unlikely (it isn’t) it still refutes the argument that evolution of such systems is impossible.
It always amazes me that creationists demand solid evidence and mathematical calculations for all hypothetical explanations based on evolution but they aren’t willing to provide even a brief explanation of how intelligent design works, let alone evidence or calculations. “God did it” seems to be sufficient explanation for every perceived gap.
Any truly honest creationist has to admit that there are several ways for irreducibly complex systems to evolve by natural means. But once they admit that, they don’t have a case. Behe can’t admit that the simple scenario described above is even possible because it means that his first book is wrong. He has to show that the scheme shown in the first figure above is impossible. He can’t do that.
When Bilbo objected that Professor Moran was misrepresenting Behe’s position, Moran doubled down (capital letters are Moran’s; emphases are mine):
Please stop trying to shift the burden of proof. Creationists argue that it is IMPOSSIBLE for irreducibly complex systems to evolve by natural means therefore there must be an intelligent designer. Do you believe that the evolution of irreducibly complex structures is IMPOSSIBLE? If so, has someone demonstrated the truth of that claim?
I’ve just described a way to evolve irreducible complexity without the need of an intelligent designer. You have to prove to me that it’s impossible, otherwise your argument for the existence of gods collapses.
In a later comment, Professor Moran fired a final parting shot at Intelligent Design advocates:
But no one is interested in the mere possibility of a god or gods that build irreducibly complex systems from time to time. We want to know if that’s plausible or probable. Show me your calculations.
Now, I should point out here that Professor Moran totally misrepresented Dr. Michael Behe’s argument. In his first book, Darwin’s Black Box (Free Press, first edition, 1996), Professor Behe freely conceded that “if a system is irreducibly complex (and thus cannot have been produced directly), however, one can not definitely rule out the possibility of an indirect, circuitous route” (1996, p. 40). What Behe declared impossible was not the evolution of an irreducibly complex system via unguided natural processes, but the direct evolution of an irreducibly complex system via incremental adaptations: “An irreducibly complex system cannot be produced directly (that is, by continuously improving the initial function, which continues to work by the same mechanism) by slight, successive modifications of a precursor system, because any precursor to an irreducibly complex system that is missing a part is by definition nonfunctional” (1996, p. 39). Moran should be aware of this fact, since he has a copy of Behe’s book, so I can only conclude that he is deliberately distorting Behe’s words and setting up a straw man for the amusement of his readers.
Moran also claims that Professor Behe, in his response to the paper by Lukeš et al., “claims that the scenario seems impossible (to him).” That’s just flat-out false. What Behe actually says is: “I think their hypothesis of CNE [constructive neutral evolution – VJT] as the cause for the interaction of hundreds of proteins — or even a handful — is quite implausible.” “Implausible” and “impossible” are very different terms, Professor Moran.
Getting to Torley’s paradox
But Larry Moran may not have noticed that the argument he puts forward in his comments has a paradoxical implication. It would mean that for any pattern that we happen to observe in Nature, regardless of how complex and specified it is, we would never be justified in drawing the general inference: this pattern was designed by an unknown intelligent agent. What’s more, if Moran’s argument is right, then any specific hypothesis – no matter how far-fetched or unlikely – for how this or that unguided process could have produced the pattern in question would be superior to the general hypothesis that some intelligent agent had produced it.
Why do I say that? Let’s look at Moran’s own words:
It always amazes me that creationists demand solid evidence and mathematical calculations for all hypothetical explanations based on evolution but they aren’t willing to provide even a brief explanation of how intelligent design works, let alone evidence or calculations…
…[N]o one is interested in the mere possibility of a god or gods that build irreducibly complex systems from time to time. We want to know if that’s plausible or probable. Show me your calculations.
In other words, Moran thinks that the only thing we can positively say about a generalized intelligent agent is that there is a possibility of it building a given irreducibly complex system S. We can’t infer that such an occurrence is probable, however, as we have no way of predicting what such an agent would do, in the absence of a more detailed description of the agent itself.
But if that’s the argument that Moran is making, then we can go further, and push it to its logical conclusion. After all, the number of irreducibly complex systems that a generalized intelligent agent might produce is infinite, since there is no limit to the variety of possible patterns that an intelligent agent could generate. (This or that intelligent agent may be limited in what it can generate, but an intelligent agent whose nature is left unspecified would not be subject to any constraints.) Hence the probability that an intelligent agent in general would produce any particular complex system S turns out to be 1 divided by infinity, or an infinitesimal number, which is indistinguishable from zero.
By contrast, if we consider any specific hypothesis – no matter how inherently unlikely it may be – describing how an unguided process P might have produced a system S, which exhibits a high degree of specified complexity, then the probability that P will produce S will always be measurably greater than zero, even if this probability is astronomically low. Since 1/N (where N is large and finite) is necessarily greater than 1/infinity, it follows that any explanation of a specified complex system S which invokes an unguided process P will always be better than an explanation which invokes a nondescript intelligent agent.
Carl Sagan’s Contact and the signal from space
Readers who watched the 1997 movie Contact will recall that the action begins with the discovery of a signal featuring a repeating sequence of prime numbers. The signal is apparently being sent from the star Vega, but later on in the movie, Dr. Eleanor Arroway, who works for SETI, eventually makes contact with an advanced civilization on an unknown planet, which is capable of constructing and traveling through wormholes.
In any case, the point I’d like to make here is that if a signal featuring a repeating sequence of the first 100 primes (say) were detected in outer space, then even if scientists were unable to locate the source of the signal, the inference, “This signal was produced by an unknown intelligent agent” would be a perfectly reasonable one. I think Professor Moran would agree with this point. But the problem is that his own argument would disallow us from drawing this obvious conclusion. On Moran’s argument, the probability that “an unknown intelligent agent” would send a signal containing the first 100 primes is infinitesimally low, as there are infinitely many possibilities for it to choose from, when sending a signal. On the other hand, the probability that even a vastly improbable natural process – such as Hoyle’s “tornado in a junkyard” – would produce such a repeating signal is measurably greater than zero, despite being astronomically low: it’s 1/N, for some very large but finite value of N. So if Moran’s argument is correct, then the inference, “This signal was produced by an unknown intelligent agent” would be an unreasonable one. That, I have to say, is a massively counter-intuitive result, to put it mildly.
Possibility vs. capability: the error in Professor Moran’s logic
So, what is the fallacy in Professor Moran’s argument? The flaw, as I see it, is that Moran confuses the notion of mere possibility with the more robust notion of capability. We can say that it is possible for an unguided process P to generate a specified complex system S, but when talking about an unknown intelligent agent, we do not normally confine ourselves to saying that it is possible for the agent to produce system S. Instead, we say that the agent is capable of producing S.
What, you might ask, is the difference between possibility and capability? The former denotes a non-zero probability (e.g. of s specified complex system S arising via process P), whereas the latter refers to an active power or capacity residing in the agent, enabling him/her to produce the system in question. If the agent has this power, then nothing more is required from outside, in order for the agent to produce S. All that the agent needs to do is formulate the intention of doing so.
Formulating the right Intelligent Design hypothesis
Finally, Professor Moran fails to realize that the Intelligent Design hypothesis which needs to be evaluated against any naturalistic explanation of a specified complex system S is not:
(1) Some intelligent agent which is capable of producing S exists
but rather:
(2) Some intelligent agent which is capable of producing S, decided to do so.
The reason is that we already know that S exists. The only question is: what produced it? Was it an intelligent agent or some unguided process?
Given hypothesis (2), we no longer have to trouble ourselves over the fact that an intelligent agent may be capable of producing infinitely many designs, apart from S. Instead, we can straightforwardly argue that our observation of S is not at all surprising, since an intelligent agent will normally do what it has decided to do and is capable of doing. The agent’s decision is built into the design hypothesis.
The broad naturalistic hypothesis which is compared with our Intelligent Design hypothesis will be one of the form:
(3) Some natural process which has a non-zero probability of producing S, did so.
If we have good grounds for believing that a small finite set of natural processes {P1, P2, P3, … Pn} are overwhelmingly more likely to generate S than all other known natural processes put together, then we may resolve the question of whether S is the product of intelligent design by focusing on this restricted set of processes. And provided that we can find a natural process such that the probability of S arising via this process exceeds Dembski’s Universal Probability Bound (which we can conservatively define as 1 in 10^150), we are perfectly entitled to opt for a purely naturalistic explanation of system S. For that matter, if we find a disjunction of processes {P1 or P2 or P3 or … or Pn} such that the probability of S arising via one or more of these processes exceeds 1 in 10^150, we are entitled to infer that system S arose via one or more of these processes. But if we know of no process or set of processes whose likelihood or generating S exceeds Dembski’s Universal Probability Bound, then by default, we should opt for Intelligent Design as the most likely explanation. Even if we have absolutely no idea who the intelligent agent is or why the agent chose to generate S, there’s one thing we do know: intelligence is capable of generating specified complex systems. That fact alone makes the inference to Intelligent Design a rational one. Of course, such an inference is provisional, insofar as it is based on what we currently know, but all science is like that.
(UPDATE: The long odds mentioned above also serve to refute Professor Moran’s argument that the existence of God is very unlikely. (Intelligent Design proponents have insisted ad nauseam that the Designer need not be a Deity, but Professor Moran thinks that we’re all lying.) But even if that were the case, the inherent likelihood of God’s existence certainly cannot be lower than 1 in 10^150. For even if every event in the history of the cosmos counted as prima facie evidence against God’s existence, the total number of such events is still less than 10^150. Thus using Laplace’s “sunrise argument,” we can show that the inherent likelihood of God’s existence could not fall below 1 in 10^150. What this means is that if we can point to a system S exhibiting a high degree of specified complexity, such that the probability of such a pattern arising via unguided processes is far lower than 1 in 10^160, then it follows that Intelligent Design is much more than 10^150 times more successful than unguided natural processes, as an explanation of the pattern. In this way, the inherent improbability of God’s existence can be overcome by a sufficiently powerful piece of evidence pointing to intelligent design as an explanation. Thus even if the Designer could only be a Deity, it would still be rational to infer that He exists.)
Conclusion
In conclusion, I’d like to return to a remark made by Bilbo on Professor Moran’s thread. Bilbo correctly pointed out that Moran had misconstrued the argument for Intelligent Design:
…[T]he ID argument isn’t that God exists. It is that one or more designers does or did exist. And the argument is the same kind of argument that SETI uses: X looks designed. We don’t know a non-intelligent way to design X. Therefore, it is reasonable to believe that X was intelligently designed.
In my opinion, it’s not an airtight, rigorous, scientific argument. But until one demonstrates that there is a plausible, probable way to evolve complex biological systems, it is at least a reasonable hypothesis.
For my part, I would modify Bilbo’s argument slightly. Instead of simply saying that “X looks designed,” I would prefer to say: “X possesses the hallmarks of a designed object.” I would also revise the middle premise to read: “Despite extensive searching, we have not found any non-intelligent process that would be likely to generate X even once in the history of the observable universe.” (In other words, all known natural processes fall below Dembski’s Universal Probability Bound.) However, Bilbo’s conclusion that “it is reasonable to believe that X was intelligently designed” seems to me a very good way of putting it. And I would certainly agree that it’s not an airtight argument, nor is it meant to be – although I would still call it a scientific inference. It’s an abductive inference to the best explanation of a phenomenon found in Nature.
But if Professor Moran honestly believes that a general Intelligent Design inference of the form, “This system was produced by an unknown intelligent agent” is never rationally warranted, and that we may never make an intelligent design inference without some specific knowledge of the agent and/or its motives, then I would suggest that what divides us is not science, but our philosophical premises. In that case, all I can suggest is that Professor Moran (and those who think like him) should continue doing science in their way, and Intelligent Design advocates will do it in a different way – and maybe, some decades hence, it will become apparent which approach is the more scientifically fruitful one.
What do readers think?