Is “Directed Evolution” Darwinian? [with addendum]

_{William Dembski

April 11, 2007

Darwinism, Evolution, Intelligent Design}

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I posted a reference the other day to a peer-reviewed paper by two Finnish ID-supporters that I claimed supported ID. The paper highlighted that evolutionary methods work to the degree that they are directed. As is typical with our detractors, whenever a pro-ID paper by pro-ID scientists comes out in a peer-reviewed biology journal, they try their best to show that it doesn’t actually support ID. An example is the following post at PT by Steve Reuland:

pandasthumb.org…the_proid_paper

In reading Reuland’s critique, try to keep track of “rational design,” “directed evolution,” and “Darwinian methods.” Reuland conflates the last two. In so doing, Reuland completely misses the boat. So let me spell it out: DIRECTED EVOLUTION IS NON-DARWINIAN. DARWINIAN EVOLUTION IS NON-DIRECTED. I’ve been saying this now for close to a decade (see ch. 4 of my book No Free Lunch). Just because the word “evolution” is used doesn’t mean that homage is being paid to Darwin. “Directed evolution” properly falls under ID.

[Steve Reuland, commenting at the Panda’s Thumb on this post, claims that I’ve misrepresented him and the paper. If he but were to read the paper closely, he would find that it distinguishes between Darwinian evolution as an “inspiration” to directed search and “Darwinian blind search” as inherently limited. Darwinian evolution, which is blind, is the inspiration for evolutionary computing, which employs well-crafted fitness landscapes to achieve ends and therefore is not blind — and therefore is properly a branch of ID and non-Darwinian. Yes, we’re playing a turf war here. But it will not do to have Darwin discard teleology and then to claim teleological processes as Darwinian. This is an abuse of language. Leisola and Turunen skirted the edge yet nuanced their views adequately; but Reuland is guilty of it.]

Comments

Atom wrote: But this doesnÃ¢â‚¬â„¢t have much to do with either: A) defining NS as a force and answering what exactly it Ã¢â‚¬Å“causesÃ¢â‚¬Â (other than differential reproduction, which is necessary for natural selection to occur in the first place) or B) showing how we can define fitness without ultimately having that definition reside in greater differential reproduction, even if removed by one or two steps. But IÃ¢â‚¬â„¢d like to hear more of your thoughts on the topic. You can help me sharpen my own thoughts.
Lewontin essentially pointed out that NS is a force when it's a force, and it's not when it's not. Thus, NS entirely superflous and can't be invoked as a general principle. Check out this devastating crtique of fitness by Lewontin in 2003 Santa Fe 2003 Stanley Salthe considered it a nail in NS's coffin, so I credit Salthe with pointing me to the article:
In modern evolutionary theory, however, Ã¢â‚¬Å“fitnessÃ¢â‚¬Â is no longer a characterization of the relation of the organism to the environment that leads to reproductive consequences, but is meant to be a quantitative expression of the differential reproductive schedules themselves. DarwinÃ¢â‚¬â„¢s sense of fit has been completely bypassed. .... How, then, are we to assign relative fitnesses of types based solely on their properties of reproduction? But if we cannot do that, what does it mean to say that a type with one set of natural properties is more reproductively fit than another? This problem has led some theorists to equate fitness with outcome. If a type increases in a population then it is, by definition, more fit. But this suffers from two difficulties. First, it does not distinguish random changes in frequencies in finite populations from changes that are a consequence of different biological properties. Finally, it destroys any use of differential fitness as an explanation of change. It simply affirms that types change in frequency. But we already knew that.
Those were the highlights, but the rest of the article is worth reading. The only time fitness is meaningful is in the repeatability of results, i.e. we can predict how a bacterial population will evolve inside a persons body in response to an antibiotic. But this isn't much of an insight in that we expect similar outcomes for similar situations!!!! The interesting question is whether selective forces exist to create large-scale biological innovation, not just change. The notion of similar outcomes for similar situations gives no insight into the forcefulness of NS as a means of creating large scale innovations. Wind and rain can change the shape of mountain. Mount rushmore is a mountain with a changed shape. Does that mean wind and rain shaped mount rushmore since wind and rain can shape mountains? Absolutely not. There is an analogous difficulty in asserting NS can effect the kind of biological change that can create large scale biological novelty.scordova_{April 12, 2007
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Atom wrote: But this doesnÃ¢â‚¬â„¢t have much to do with either: A) defining NS as a force and answering what exactly it Ã¢â‚¬Å“causesÃ¢â‚¬Â (other than differential reproduction, which is necessary for natural selection to occur in the first place) or B) showing how we can define fitness without ultimately having that definition reside in greater differential reproduction, even if removed by one or two steps. But IÃ¢â‚¬â„¢d like to hear more of your thoughts on the topic. You can help me sharpen my own thoughts. Lewontin essentially pointed out
scordova_{April 12, 2007
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I can't believe I'm still watching this thread so closely, but...
Ã¢â‚¬Å“non-randomÃ¢â‚¬Â ... seems designed to conflate natural selection with intentional selection, by using a fuzzy definition of Ã¢â‚¬Å“non-randomÃ¢â‚¬Â to make it sound like both are directed. Natural selection is not random with respect to the environment. However, the environment itself is random, by which I mean, it doesnÃ¢â‚¬â„¢t act with any intentions or goals in mind.
Since I'm the one who used the term non-random, let me defend my use of it. I in no way meant to imply that an environment acts with intentionality. Non-randomness is not synonymous with intentionality. Lots of things are non-random without being intelligent. Objects unhindered by air resistance will fall at 9.8 m/s/s on earth. Acceleration due to gravity is non-random. That doesn't mean gravity has any goals. I say natural selection in a given environment is non-random, although it does fluctuate. Breeding programs are also non-random. That does not mean, however, that natural selection is exactly the same thing as a breeding program. There are important qualitative differences. Importantly, in breeding, those with the best selected-for traits are only allowed to mate with others with the best selected-for traits; in the wild organisms are allowed to mix freely, which is a serious hindrance.motthew_{April 12, 2007
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Calling directed searches "Darwinian" is tantamount to defining Darwinism away. It is to conflate natural selection with selection simpliciter, which renders the "natural" part meaningless. If we use that definition, then anytime anyone selects anything, we can call it "natural selection", in which case, what good is the concept? It is precisely the point of natural selection that it is undirected, ie, there are no intentions or goals involved. Darwin specifically contrasted this with animal breeding, which, like evolutionary algorithms, is directed selection, in which goals are involved. If you ignore or equivocate on this crucial distinction, you render the concept of natural selection vacuous. And as Bill says, it's an abuse of the language to boot. If you can't speak clearly and consistently, you aren't thinking clearly and consistently. Btw, the claim that natural selection is "non-random" is true in one limited sense, but also misleading almost to the point of culpability. That commonly uttered statement seems designed to conflate natural selection with intentional selection, by using a fuzzy definition of "non-random" to make it sound like both are directed. Natural selection is not random with respect to the environment. However, the environment itself is random, by which I mean, it doesn't act with any intentions or goals in mind. It just happens to be the way it is at any given point in time (unless the environment itself is being controlled to achieve someone's intentions, in which case we're back to intentional selection).Deuce_{April 12, 2007
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"A) defining NS as a force and answering what exactly it Ã¢â‚¬Å“causesÃ¢â‚¬Â (other than differential reproduction, which is necessary for natural selection to occur in the first place)" --Atom This thread has jumped forward quite a bit since last I was here. Several of you have made some excellent points. One more attempt to convince Atom... As Darwin himself noted in the quote J provided, "natural selection" is essentially a metaphorical term, a linguistic term that blanketly refers to all the disparate *environmental causes* that, when interacting with particular organismal traits, yield differential reproduction among organisms. In the case of artificial selection, you don't need such a blanket term; you can simply envision a breeder. Yet Atom, you are willing to say that the breeder is a causal force but not the disparate environmental mechanisms involved with natural selection. I do not understand the disconnect. (I rather dislike talking of forces and causality because of metaphysical connotations, but I simply assert here that natural selection is *no less* a force than is artificial selection despite the presence of intelligence in the latter). Yes, differential reproduction is *required* for natural selection in the sense that it is necessary to *fulfill* the full criteria for "natural selection." *BUT JUST AS IMPORTANT* for meeting the criteria for natural selection is the *action* of various aspects of the environment towards *generating* that differential reproduction. It is this latter component of the criteria that I think Atom is neglecting in his argument. As for defining fitness without circularity, it all rests in the specific details of individual biological instances. What relative fitness means for bird beaks in the context of Darwin's finches, for example, resides in just *how* the beak physically/materially *contributes* to differential reproduction among finches. Not simply the differential reproduction itself. The informative content rests in the details. Differential reproduction, without any associated fitness, is simply genetic drift. If anything, contemplating the notion of genetic drift should illuminate things a bit. Genetic drift, by definition, entails differential reproduction, but genetic drift is decidely NOT natural selection. So what distinguishes genetic drift from natural selection? What constitutes that difference is the crux of this whole discussion. It is the selective "pressure," and it comes from diverse environmental sources.great_ape_{April 12, 2007
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I'm not arguing arguing for the predictability of natural selection. I'm not arguing for evolutionary storytelling of natural selection. I'm not arguing for natural selection as evidence for evolution. I'm not even arguing for the usefulness of natural selection. What I am arguing for is that natural selection is is not a meaningless concept, it is quite real, and is the non-random component of differential success in reproduction. Any acknowledgment that different ecologies have different types of organisms living in them, is, in my mind, a recognition of what I've just said.motthew_{April 12, 2007
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Can an unconscious director write a script?
You haven't seen many movies lately, have you?DonaldM_{April 12, 2007
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I just love the PT gang. They can always be counted on to trip over their own tongues!DonaldM_{April 12, 2007
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:) @ j. Sal, welcome into the discussion. You bring up the point of similar organisms needing to fulfill similar constraints, which makes sense due to their sharing the same "pieces of machinery" for their replication. Thus one change in machinery that leads to better differential reproduction should cause a similar response in similar machinery elsewhere. If they're gonna survive, they need the same mods, the ones that cause greater differential survival. But this doesn't have much to do with either: A) defining NS as a force and answering what exactly it "causes" (other than differential reproduction, which is necessary for natural selection to occur in the first place) or B) showing how we can define fitness without ultimately having that definition reside in greater differential reproduction, even if removed by one or two steps. But I'd like to hear more of your thoughts on the topic. You can help me sharpen my own thoughts.Atom_{April 12, 2007
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Atom (60, 78):
I honestly want to understand what is at the root of NS and if the concept can be framed in a non-circular, or even causal way. ... IÃ¢â‚¬â„¢m pressing only because I want straight, simple, answers.
How about this: Charles Darwin, OOS:
Several writers have misapprehended or objected to the term Natural Selection... [Natural selection] implies only the preservation of such variations as arise and are beneficial to the being under its conditions of life... It has been said that I speak of natural selection as an active power or Deity; but who objects to an author speaking of the attraction of gravity as ruling the movements of the planets? Every one knows what is meant and is implied by such metaphorical expressions; and they are almost necessary for brevity. So again it is difficult to avoid personifying the word Nature; but I mean by nature, only the aggregate action and product of many natural laws, and by laws the sequence of events as ascertained by us.
Hence, natural selection is simply determination by "the sequence of events as ascertained by us." Helpful?j_{April 12, 2007
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The situations where survival of the fittest is an appropriate and somewhat useful metapor is when there are reproducible situations that get identical oucomes. For example, two petri dishes with the same kind of bacteria and identically treated with the same antibiotic will get the same results. Survival of the fittest in one context accurately predicts the survival of the fittest in the next, and this will help us predict what the surviving organism will look like if they survive at all. I can, for example by applying pesticide to an insect population have an idea of how another insect population will evolve if were dealing with similar populations of the same species as in my control group. This is helpful to drug development. I point out this is Blythian evolution, not Darwinian evolution. Where survival of the fittest is a worthless and useless metaphor is in the are of a population surviving out of pure luck. Technically, they had the trait of being lucky and thus were the most fit. Totally useless.... And even though the metaphor is useful for predicting evolution in the present day, it doesn't bode well for Darwinian evolution. In almost every case we have preservation of species, not origin of new ones!!!!!! Salvadorscordova_{April 12, 2007
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Ok they're showing up immediately now...Thanks Dave!Apollos_{April 12, 2007
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DaveScot said:
Are most or all of your comments showing up right away?
They were being posted immediately until I added that pseudo code sample in this thread yesterday, then I think I got flagged as spam from there on out. Supposedly Akismet will correct it eventually if they're marked as "not spam" (Their web site says it can take a day or two).Apollos_{April 12, 2007
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To put it another way: When assesing fitness, we only consider traits that help or hinder net reproduction. (A true statement.) Those organisms with these traits (the beneficial ones) will have higher differential reproduction than those without them. (Another true statement.) Therefore, the traits which cause differential reproduction will cause differential reproduction, which then explains why when we see differential reproduction these traits were the cause. (A true statement due to its logical form. So a tautology.) "Traits which cause x will cause x, which then explains that why when we see x these traits were the cause." Convoluted, but logically true and the essence of what you're saying.Atom_{April 12, 2007
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...but then I go on to find specific reasons that they arenÃ¢â‚¬â„¢t fit instead of stopping there.
But motthew, your "reasons" are only reasons because they lead to or take away from survivalibity in the end. Why not say that they aren't fit because they're not "red" enough? Because "redness" doesn't help nor hinder survivability/reproduction. Thus, it doesn't affect their "fitness." You are simply removing the problem by one step then pretending it goes away. "Frogs are fit because of x. X is defined as fit because of y. Y is defined as fit because it leads to greater survivability. Therefore, frogs are more fit due to x isn't circular reasoning..." - see the problem?Atom_{April 12, 2007
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Atom: It still sounds to me as if you are in fact using it in the rhetorical sense. You're claiming that in the phrase, "the fit survive," "survive" and "fit" are semantically equivalent, because we define what is fit by what survives. If fitness is defined by survivability, then you're quite right. But I disagree that this is how fitness is being defined. Frogs aren't fit for the desert (in part) because they need lots of water for their reproduction. This is one instance of defining fitness. I use the fact that frogs don't survive well in the desert as an indicator of their lack of fitness for the desert, but then I go on to find specific reasons that they aren't fit instead of stopping there. See the difference?motthew_{April 12, 2007
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The first definition from your link: "Tautology (logic), a statement of propositional logic which can be inferred from any proposition whatsoever " This is what I mean when I use the term. A statement that is always true can be inferred from any proposition whatsoever, even from none. I am not using it in the rhetorical sense.Atom_{April 12, 2007
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motthew, a tautology is a statement that is always true due to its logical form. An argument of the form "if x then x" is always true, regardless of what we plug in for x. Even "if x and y and z and q and p and l...then x" is still always true. It doesn't matter if we "add" more information (y,z,q,p, etc) or not.Atom_{April 12, 2007
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"I was questioned by great_ape for saying that NS is not a force, in the sense that what is causes is the same as the cause itself, or in other words, it Ã¢â‚¬Å“causesÃ¢â‚¬Â nothing.)" NS, ie, the environment, does seems to be a cause. It is a non-random cause of death. NS can only subtract, it can never add. The novel information must come ultimately from a source. Darwinistas lean on random mutation ultimately without bothering to probe the implications of any particular view of the source of such randomness. "Random" ultimately is no different than simply saying "unknown" or "unpredictable." It is a negative term conveying ignorance only. So what is RS+NS really? It is the non-random environment acting upon molecular effects (via death to some) from some unknown or unpredictable source. That's it. No more no less. (All of the anti-ID nonsense is simply the (generally unstated) philosophical premises of the claimant that having nothing whatsoever to do with RM+NS.)mike1962_{April 12, 2007
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I hope someone got something out of that rather lengthy exchange. Haha. I know I did.motthew_{April 12, 2007
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So, to collapse the chain of how we defined a given trait as beneficial, we can say that long fur is ultimately beneficial in the cold because it helps an organism reproduce.
A tautology is not a circular argument, a tautology is a restatement of something so that no extra information is given. Are you saying that you said nothing of any information value in the following statement?
Let us stick with the example of long fur for now. We say it is beneficial because (special definition) it helps retain heat. Retaining heat is beneficial because it helps an organism survive, which helps it to reproduce.
Of course you've added information! You told us that fur retains heat, and heat helps organisms survive (ignoring any one of a thousand factors). Again, I say, survival of the fittest tells us that we can discern reasons for why some organisms thrive, and that in turn shows us that natural selection has endpoints though they are without willful intent and ever fluctuating. Maybe it is useless as a statement in and of itself, but when you apply it to a certain situation, it's quite clearly useful.motthew_{April 12, 2007
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Is it fair to say that youÃ¢â‚¬â„¢re essentially saying something like this: Survival of the fittest gets us nowhere, because whereas we can theoretically understand the reasons why some organisms will reproduce more successfully than others, the fitness landscape is so comlicated in such a constant state of fluctuation that a clear trend toward organisms with certain features can never be properly established?
In a word, no. I am not saying that. I am taking it a step further: for any special definition of fitness you come up with ("long fur is more fit in a cold environment") it can always be shown that it is a circular definition, even if a couple steps removed. (My original point, however, was not the logical circularity of NS, which I already felt was established. I was questioned by great_ape for saying that NS is not a force, in the sense that what is causes is the same as the cause itself, or in other words, it "causes" nothing.) Let us stick with the example of long fur for now. We say it is beneficial because (special definition) it helps retain heat. Retaining heat is beneficial because it helps an organism survive, which helps it to reproduce. (If survival didn't ultimately aid in reproduction, it would become irrelevant to our abstract view of Natural Selection: we are only concerned with replicators out-replicating against a constraint space). So, to collapse the chain of how we defined a given trait as beneficial, we can say that long fur is ultimately beneficial in the cold because it helps an organism reproduce. Fit because it helps reproduction. Better reproduction because it is fit. The circle.Atom_{April 12, 2007
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Oh, I contradicted myself. I should have said "Natural selection alone isn't meant to explain much," instead of saying that it's not meant to have any explanatory power. (Extracting foot from mouth)motthew_{April 12, 2007
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Atom: Okay. Is it fair to say that you're essentially saying something like this: Survival of the fittest gets us nowhere, because whereas we can theoretically understand the reasons why some organisms will reproduce more successfully than others, the fitness landscape is so comlicated in such a constant state of fluctuation that a clear trend toward organisms with certain features can never be properly established? If so, I partially agree. There is no single end goal of natural selection. That which is labeled "fittest" is extremely elusive and always changing. But there are some factors in classifying the fitness that are clearly dominant and not so unstable: desert vs. tundra vs. rainforest, etc being one of the biggest. And thus we can say with some degree of confidence that certain factors brought about the dominance of certain types of organisms. If it still bothers you that this is a tautology then I'm not sure what else to say about it. Natural selection alone isn't meant to have explanatory power. Supposedly coupling it with the development of novel traits is. And thus my main point is, just because there is no teleological intent behind something, does not mean that there is no directional force in it.motthew_{April 12, 2007
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Mistake! What I meant was: A: That which is fittest survives. B: X is fittest. Therefore: X survive. (A good example of begging the question, as well.)motthew_{April 12, 2007
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Thank you for the answer motthew.
Phrase 2, on the other hand, is what I think Ã¢â‚¬Å“survival of the fittestÃ¢â‚¬Â is really getting at. ItÃ¢â‚¬â„¢s a recognition that when we look at a given environment, we can find reasons that certain types of organisms can thrive in it.
True and agreed. But it doesn't solve our problem or escape the circle. "we can find reasons that certain types of organisms can thrive in it." - true: it is because they have traits which allow them to survive. Which traits are these? It depends on the envirionment. It may be low water consumption for desert, or long fur for the cold. But how do we define low water consumption or long fur as a "trait which allows it to survive"? By the net results of what happens when you put those traits in those environments. Those traits that survive are the survivors, thus are the beneficial/fit traits. You're saying, one step removed, "The reason some organisms suvive in environment A is because they have trait X. Trait X helps it survive/reproduce, so is thus fitter. We know this because it survives better with trait X than without it. Therefore, organisms with trait X will survive/reproduce better than those without it." A tautology still.Atom_{April 12, 2007
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I'm actually arguing with a friend in a chat about this right now, and he's helped me to once again refine my thinking. Logically: A: That which is fittest survives. B: X survives Therefore: X is fittest. In this formal sense "survival of the fittest" is circular reasoning, a tautology. But ignore that specific phrase for a moment and think about these phrases instead: 1) "Some things survive", 2) "There are reasons some things survive." Phrase 1 gets us nowhere. It's an entirely true statement but we can't do anything with it. Phrase 2, on the other hand, is what I think "survival of the fittest" is really getting at. It's a recognition that when we look at a given environment, we can find reasons that certain types of organisms can thrive in it. Granted, there are a thousand factors in an environment, so it's often difficult to really understand why certain organisms survive and others don't. But there are some factors that are so obvious they develop a clear an understandable relationship. Take again for example the desert. It's obvious why frogs don't dominate in the desert. They have to have water for their reproductive cycle. My friend pointed out that fish actually do live in the desert, and he's right! But it's telling that we're amazed that fish live in the desert. It shows that we are able to predict statistically, though not particularly, what kinds of organisms will thrive in certain kinds of environments. So while "survival of the fittest" is a poor way of expressing it, what it's really getting at is that we can take what we know about what organisms live where, and discern some of the major factors for why they're there. I'm arguing for the self-evidence of what has unfortunately been labeled "survival of the fittest" and "natural selection." What use it is to evolutionary theory is another matter.motthew_{April 12, 2007
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"survival of the fittest"? Darwinism is a religion of death.DanaMcgee_{April 12, 2007
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motthew, please explain what "survival of the fittest" is, if not "survival of the survivors". If you have reached a clear, non-circular definition of Natural Selection as a force, then please explain it. Then we can move past this "quibble" (to use jerry's assesment.) We can explain gravity as a force in two or three sentences. Please do the same for NS as a force and clear up any misunderstandings I may have.Atom_{April 12, 2007
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Okay, I'll go back on my word (oops!) and respond again:
Actually, we label the FORCE which CAUSES the falling of the bullet Ã¢â‚¬Å“gravityÃ¢â‚¬Â, not the falling itself. Or else weÃ¢â‚¬â„¢d have a useless tautology: Ã¢â‚¬Å“the falling of the bullet causes the falling of the bullet.Ã¢â‚¬Â

No, we say Ã¢â‚¬Å“the bending of spacetime/graviton exchange(different and separate from the falling of the bullet) causes the falling of the bullet.Ã¢â‚¬Â We have a cause logically separate from the effect in the case of real forces.
Well, you caught me oversimplifying and conflating scientific ideas. I didn't want to complicate the matter. But I can counter by simply taking it down to the fundamental levels that you want to take it down to. Gravity is, according to General Relativity, a manifestation of the shape of spacetime. But what is the explanation for the shape of spacetime, not as a description of the interaction of the parts of the spacetime system, but rather the underlying causes for the spacetime's existence in the first place? Eventually we always get to a point in science where, at least for a time, we can describe what we observe or logically derive from observations, but are clueless as to the underlying causes of it. It's no use to pick on "survival of the fittest" because it's a self-evident phenomenon that we don't have an underlying explanation for. It does not make it a valueless proposition. I might note that thanks to this discussion, today is the first day that I've clearly understood that "survival of the fittest" is actually quite different from "survival of the surviving." The first is not a tautology, the second is. Which is really what I've been trying to work out in this conversation all along.motthew_{April 12, 2007
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