Newton famously wrote [1] [2]:
I have not as yet been able to discover the reason for these properties of gravity from phenomena, and I do not feign hypotheses… It is enough that gravity does really exist and acts according to the laws I have explained, and that it abundantly serves to account for all the motions of celestial bodies.
as a response to those who challenged him to provide causes of gravity. He said, “Hypotheses non fingo,” or, “I feign no hypothesis,” or if you will, “I haven’t even a guess.”
Earlier in a letter he wrote:
That one body may act upon another at a distance through a vacuum without the mediation of anything else, by and through which their action and force may be conveyed from one another, is to me so great an absurdity that, I believe, no man who has in philosophic matters a competent faculty of thinking could ever fall into it.
These passages show that Newton recognized a fundamental causal problem within his theory: that although his mathematics described gravitational physics, it did not provide a causal explanation. It was not until General Relativity 200 years later was this problem solved.
Recently another major fundamental theory of science has been accused of lacking the proper causal structure: Fodor & Piatelli-Palmarini’s attack on evolution, What Darwin Got Wrong. Consider what Fodor says in his recent reply to Block and Kitcher,
A mere chronicle of instances of adaptation would not therefore amount to a theory of adaptation. It would just be “natural history.” We haven’t the slightest doubt that Darwin thought that he had discovered a theory of adaptation. It was, to be sure, a pretty thin theory, as it would have to be in order to apply to evolving creatures as such, whatever their phenotypes and whatever their ecologies.
He is saying that evolution is a mere chronicle of natural history — not a cause of it — just as Newton’s gravitation described gravity without revealing its causal structure. Later he says,
[Biologists should] give up on the project of finding a mechanism for evolution and study the fixation of adaptive traits case by case. Since all the evidence suggests that they are extremely heterogeneous, this should keep evolutionary biologists busy well into the indefinite future.
This means that biologists should give up on repairing evolution and just try to explain individual phenomena moving forward, just as physics moved forward even as Newton knew his theory was on metaphysical shaky ground.
Hence it is Fodor now saying, “Hypotheses non fingo,” because he believes he can describe natural history accurately, but also has no guess as to what caused things to work out the way they did.
* * * * *
In light of this analysis, consider this statement from Block and Kitcher’s counter argument:
After our critique, Fodor and Piattelli-Palmarini have apparently decided that the crucial point is the lack of a “theory” of natural selection. But, as we have noted here, nobody needs a “theory” of the type they demand.
And this from Sober’s recent review [pdf]:
What is the net gravitational force now acting on the earth? That depends on the mass of the sun, the moon, the stars, and of everything else. It does not follow that there are no laws of gravity, only that the laws need to have numerous placeholders. FP may object to my analogy because it is always the mass of these various objects and their distance from the earth that are relevant to the gravitational force that the earth experiences. My reply is that this makes no difference…
Neither has understood the argument as presented above. If Block and Kitcher had understood, then they would have recognized that yes, for the vast majority of people, the “‘theory’ of the type they demand” is unnecessary, but it is, nevertheless, of critical importance to the likes of Newton and Einstein. If Sober had understood, then he wouldn’t have used the worst possible example to make his point: by saying it is “always the mass of these various objects and their distance from the earth that are relevant,” and not mentioning motion, we know he was only thinking about Newtonian Mechanics.
* * * * *
Should we, with Fodor, believe that we are stuck in a philosophical absurdity?
No. What I said in my original criticism of Fodor, found in What Fodor Got Wrong (18 March 09), still applies. Though the above description of the problem is likely clearer than my analysis based on his claims that Natural Selection is statistical and that the struggle for survival is only a metaphor, the problem of causal structure is the same. My solution focuses on using individual struggles as local interactions of Natural Selection — like a gravitational field in General Relativity — and hence provides the causal structure that Fodor wanted.
[EDIT 6 April 2010: I’m thinking I gave Fodor too much credit in this post. I now think his arguments amount to saying that for each instance of evolution we have, we are merely relaying natural history, not a causal explanation. The argument I attributed to Fodor above says that evolution by natural selection is natural history. Fodor must be more agnostic about evolution’s ontology because of how he says it is possible to look for some alternative to natural selection in his reply to Block and Kitcher. My solution is still viable though: since I provide causal structure, this also provides how to describe evolution in a causal way.]
Greeting,
I will attempt this again.
1) Natural selection as an effect of descent with variation is an observable fact. It’s effect can be seen in very small changes in organism over time.
2) Natural selection as an effect that produces whole new types of organisms has never been observed directly, rather the natural selection of 1 above is believed to be sufficient to explain the origin of turtles, birds, primates, man, lung, etc., etc..
3) Number 2 above is the belief that a phenomenon which has never been observed is of necessity explained by observed phenomena and is not the product of unobserved phenomena. This belief, while it is correct in many cases (perhaps in the present case) is not certain. The belief is based on a guess – an inference. If the origin of major new body types and systems is sometimes from saltations, then such morphologies are sometimes not (properly understood) products of natural selection. If such is the case, then F&P’s argument that evolution or natural selection are simply the description of effects is essentially correct.
I want to ask two questions: 1) Do you understand that there is an inference involved in the claim that the evolution of all morphologies is by the same means as the empirically observed natural selection? 2) Can you show that saltations do not happen? Or do you admit that they might happen?
Regards,
Timothy E. Kennelly
Hi Tim,
This article actually has very little to do with the changes evolution may create in organisms. It is a comparison of certain aspects of Fodor’s argument to a problem in the history of philosophy of science and physics. I wrote it in hopes that people who are not so interested in evolution, but may have an interest in physics or general philosophy of science, might understand why I find the subject interesting and what is at stake.
To answer your questions:
1. I think I understand that there is an inference involved.
2. I’m a philosopher. I don’t go out and show anything. I have a belief that saltations are unlikely due to strong views I hold about action at a distance.
Greetings,
If Newton had been less clever, he might have suggested that since we can not see wind and we know it moves things, therefore the effect of gravity is from a wind of some kind. This would have been an inference – a rather weak inference – based on the assumption that all observed motion caused by gravity might be reasonably explained as the effect of an otherwise unobserved wind.
This kind of claim is something like the claim that the variety of life is an effect of natural selection or descent with variation (very small variation) and survival of the fittest. The inference in this case is much stronger, but it is still just an inference. If some evolutionary novelty is from saltation, then Darwin’s claim is essentially incorrect to the extent that it is understood to be an explanation of cause or an explanation of the origin of species (which I suspect is Darwin’s opinion). This is F&P’s criticim in a nut shell and if you see the inference, and admit there might be saltations, then you should be see that F&P might be right. You might add many reasons why you doubt they are correct, but you should admit that they might be correct, and given what they are trying to do this is no small statement.
The point by way of example: if the first turtle shell is not an adaptation developed over many gnerations, but a freak event, a hopeful monster, a lizard with a hard back that is born and survives to reproduce, then the turtle shell is only incidently explained by natural selection – the explanation is not causal, but statistiacal – it is only “this organism survived” and nothing more – as F&P have argued.
Regards,
Timothy E. Kennelly
Hi Tim,
I don’t understand why you bring saltation in along with F&P’s argument. Either their arguments stand or fall on the things they said, and they never said anything about saltation. My discussion only has to do with my interpretation of their arguments and a comment on why I think they are wrong.
My personal view is different – as I said in a different comment to you, I don’t believe in saltation in evolution. I appreciate your comments, but saltation doesn’t have anything to do with my post above, nor what would have happened if Newton had been less clever. I’m just confused as to how you got from what I said above to what you said in your comment.
Greetings,
I have understood you to be arguing against the idea that Darwin made an error when he argued that natural selection provides a causal (as opposed to simply incidental) explanation of the origin of species or biological diversity. I have argued that what he has done is to attribute a known effect (biological diversity) to a known natural process (natural selection acting as an effect in the process of observed descent with variation) without establishing a necessary link between them.
You indicate in a prior blog that natural selection (NS) “is a force that changes species over time.” This might be true of NS in a trivial and observable sense without at the same time requiring that NS is the cause of the diversity of life or the origin of species. This is the question that Fodor is primarily concerned with and as an empirical problem the question reamins open.
Timothy E. Kennelly
Hi Tim,
If you take a look at the last paragraph in my post, I gave a reason for why I believe that this question can be answered: Natural Selection is backed by struggles for survival. It is these struggles that you can point to when you look for what caused Natural Selection.
Yes, I see your comment. I will grant that one might believe that biological change is always small and natural selection is the force that drives the process, but such a belief is not of necessity correct. The observed novelty and variety of life might be primarily a function of very quick changes, saltations, that are simeply fine-tuned by natural selection after the event. Either case is possible, and evolution might be a mix of both these processes as well as other processes.
Will you admit that such a variety of processes might be present in the evolutionary history?
Timothy E. Kennelly
Until I see causal structure – believe you me, I had to work very hard to see the causal structure in evolution I have indicated – I am unwilling to accept other processes. I am open to any argument showing that some other causal process is at work, but I’ve not seen any such arguments as of yet.
How exactly have you seen the causal structure?
No one will reasonably deny that the organisms currently living and all organisms that lived in the past have accomplished this by virtue of survival, but this does not mean that survival is the cause of variety and novelty in the forms of life. There is an infernece in the arguments that moves from the small changes you see to all the changes necessary over hundreds of millions of years to turn a mouse into Plato, or an elephant. The whole process might not be properly understood as a function of the organism’s ability to survive in an environment and thinking in terms of natural selection being the cause of all this may lead one to think many things which might be false.
In any case, I am not saying that the process is not simply natural selection, rather I am saying that the opinion that such is the case is not necessary or evident. The small change you observe and other changes like it over millions of years might or might not be sufficeint to explain the variety of observed life. It could be that if one observed only these small changes for hundreds of millions of years that you will get a bigger or smaller mouse, or a mouse with a different color, or bigger teeth, etc., but not Plato. Plato might be the produce of changes that are not like the small ones that appear to ordinary experience.
Timothy E. Kennelly
I didn’t mean see as in see objects or pieces of evidence. I meant see as in someone would have to explain the causal structure of some other process. As of now, I believe I understand the causal structure of natural selection and think it makes sense.
If you have an argument showing that there is some other causal explanation for changes in species, please give it. I have no doubt that there are a variety of opinions, but I am not about to change my mind before I see an argument.
There are many possible causal structures, but one that has been around for some and may or may not prove correct with respect to any particular case is saltations, or large changes in one generation caused by a very unusual mutations. F&P specualte on this possibility in there book.
Although it does not provide a mechanism as such Gould’s Punctuated Equilibria, both the theory and the book with the same name, provides some reason to doubt gradualism and consider saltations or some other possible cause for non-gradual evolution.
The problem of the origin of novelty in evolution is old and it is in truth unresolved. There is no good reason to simply believe one solution to this problem is correct.
I am leary of credulity which serves no moral or practical end. It may be that the standard Neo-Darwinian picture is correct, but I will not submit to such an understanding simply because a biologist says, “You see these small changes…they add up over time and one gets big changes.” Certainly this might be, but I remain skeptical and there is no way I can know that the process does not include some bigger changes that introduce new things which are not the products of small changes over a long period of time.
Regards,
Timothy E. Kennelly
Like I said, it took me a long time to understand the causal structure in natural selection, so I appreciate your skepticism. Darwin himself was concerned about how complicated structures could evolve, but I’ve not seen any reason why, given a long enough time, small changes couldn’t eventually lead to big ones. Given that I feel I have a strong theoretical backing – and natural selection is only theory about this topic that I can say that for – I don’t feel that I am being hasty about my beliefs. You are right that many just believe things without proper thought, but I don’t think that applies to me.
As far as saltations, I haven’t seen a causal explanation for it yet: the question is how would a saltation occur. Since I see no causal way for a saltation to occur, I can’t include it in my theories about evolution. It would be ad hoc. (A small point about me: I am first a person who values argumentation skills. Death before inconsistency.)
A saltation my happen as a result of a mutation in a hox gene. The subject is discussed by F&P. They also discuss a mutation which produces a second wing in a fruit fty, it is worth looking at.
If I understand your argument, you are say that you believe that evolution might happen as described by the Neo-Darwinists because that explanation might be correct and you do not have on hand any complete theory of an alternative. I will suggest that if you look at Gould’s book PE you might wonder why the fossil record is as it is, (assuming Gould description is correct) and you might conclude that the fossil evidence suggests that the process is not necessarily anything like the Neo-Darwinian paradigm. If you do not know exactly what mechanism or mechanisms might be in play in evolution and the evidence leads you to reasonably question, then why believe that the process must have happened in one particular way.
I will gladly admit that F&P and PE might be totally wrong, but this is an empirical question and it must be resolved by evidence, not by the fact that most trained biologists hold one opinion as opposed to others.
Regards,
Timothy E. Kennelly
What is the difference between a regular mutation and a saltation? If we are both talking about genetic changes that can occur by what is considered the normal mutation process, then we just had a semantic disagreement and nothing else. I’m sorry I wasn’t clearer earlier.
But if this is the case, then it looks like you support something very close to the new-Darwinian paradigm, as you call it. There is always the issue of genetic drift where large sections of populations gain or lose a trait for no discernible reason. If you think that we should only count large mutations in natural selection, then it just means that there is more genetic drift than previously thought. You may very well be correct about this, but we are all still stuck with the question of where exactly to draw the line between drift and selection. If this is you position, I have no problem with any of it, insofar as you can back your position up with evidence.
Also, I just had a funny thought: If a saltation occurs and there is an offspring from a parent that is very different from the parent, then who does it mate with? Usually mutations are unique to each child, and if there are radical mutations, then that child will have no partners to mate with. So it couldn’t have any offspring, and the saltation would disappear.
If the organism with a major mutation could still mate with members of its species, then the genetic change must not have been so great. So it wouldn’t present much of a departure from the previous generation.
Being perfectly clear about this, I am of the opinion that the common opinion (Neo-Darwinism) might be true, true in part or simply false with respect to this very specific question.
A saltation is not the same thing as a genetic drift. Saltations might or might not happen, but if they do and they result in changes to the phenotype and the genotype and the origin of species, then the questions you have asked are fair. The process of the production of a saltation and it mating and surviving has been done artificially (with considerable intervention) and the process has been described as ‘genetic assimilation’. F&P discusses the case.
Regards,
Timothy E. Kennelly
My concern wasn’t that saltation was genetic drift, but that saltation worked perfectly well within the evolutionary framework. If saltation is just a comparatively large mutation, then I’d want to know why one mutation is considered a saltation and others are not. This is especially pressing since you say that ‘genetic assimilation’ is possible. If so, there is an upper limit on how different a product of a saltation is and an ordinary member of the species because they cannot be so different as to produce sterile offspring.
I mentioned drift because if we are just making a relative comparison between mutations, and only relatively ‘big’ mutations count, then the ‘smaller’ mutations could just be seen as drift. This would fit saltations right into the standard theory: saltations would now be normal mutations and what we used to consider normal mutations would be considered drift. This would be a change of standards, not of the theory, and the causal structure would remain intact.
Otherwise, if saltations have some other causal structure, then I’d like to have that structure explained to me. Without this, it still seems arbitrary to say that saltation does not fit into the standard causal explanation.
Greetings,
We are speaking of the relative size of mutations, but if some new body types (for example) are introduced by saltations then they are not the products of adaptation and natural selection.
The inference that observed descent and variation is sufficient to explain the observed variety of life is not correct if the observed variety is really driven by rare events. And if the events introduce otherwise unobserved novelty, then the novelty is the product of the rare events (large mutations) and not natural selection and adaptation.
Ask yourself this: does a giraffe heve a long neck and long legs and a sticky tongue so it can eat leaves off of tall trees, or does it eat leaves off of tall trees because it has long necks, long legs, and sticky tongues.
Regards,
Timothy E. Kennelly
One might be able to chnage the theory so that saltations are not a big deal, but it is important to notice two thing: 1) the theory as originally stated, and one of its most basic inferences, is changed by this means; and 2) this change will have signficant implication for evolutionary psychology.
Regards,
Timothy E. Kennelly
Hi Tim,
We may have to agree to disagree at this point. No other process has been argued to be at work here, and saying that large mutations provide a counterexample seems terribly ad hoc because the size of what counts as a mutation is not based upon a theory.
I won’t budge an iota until an argument is provided showing alternate causal structure.
You believe that the variety of life can be explained simply from observed descent and varitation, but such a thing is not necessary. Is it possible evolution happens only in this way, and never by another means? Sure. But the belief is necessary neither on rational ground nor on experiential ground. It is rather like the belief that Newton’s physics explained the motion of all bodies in the universe, a common enough belief among physicists before the start of the previous century. But, a more sober thought would have included the caveat that the universe is very big and we do not know much about it. Likewise in the present case, the variety of life is vast and our direct experience with it is vanishingly small fraction of natural history and the fossil record contains the smallest fragment of creatures from the past. In short, we would be wise notice our ignornce and admit that what seems true in case might be a distortion or a true only in part.
Regards,
Timothy E. Kennelly
I never claimed omniscience. I have no idea what is happening in very far away places. And I recognize that we learn things and come up with new and better theories. However, it does not mean what we are discussing at the moment is wrong.
Here is what matters most to me, and much more than the particulars of evolution: arguments. Until you can provide the arguments I have been asking for as pertaining to this particular topic, nothing – and I do mean absolutely nothing – will sway me. General statements about science, e.g. necessity of particular theories, negative induction about how old theories continue to be shown to be wrong, or our own limited knowledge of the universe, have no bearing on the argument I presented in the post above or on our continued discussion.
I have not argued that you are claiming omniscience, but we are claiming to know more than we really know to the extent that we exclude all other possible mechanisms in a process of which we have very limited knowledge.
If you refuse to budge one iota, that is fine, but realize you are refusing to budge from a belief.
In any case, I have enjoyed this exchange.
Hi Tim,
I’ve likewise enjoyed our conversation.
I never logically excluded other possible mechanisms: I merely require that an argument be presented to support those alternate possibilities. Without such an argument, there is no reason I should change my mind about what I believe. (I believe the earth is not flat, my name is Noah Greenstein, I have hands, etc. Just because something is a belief does not make it something that should change.)
Moreover, I ask you why you believe what you do if you cannot present an argument; how did you become convinced? There is no default position here.
I could give an argument, but it would be little more than an imagined narrative, and I would rather not provide such a thing. It is likely this kind of reluctance which makes natural selection by way of adaptation the only player in the game. One can see everything which is necessary to infer natural selection and adaptation in the immediate observation of living species, but the inference moves from the observed change to all change.
I am not convinced that salations are an ordinary part of the evolutionary process, rather I hold some doubt that the process can be fully explained by the conventional theory. Perhaps it can, but I will retain doubt for now.
Belief in that which is defined strictly by convention or ordinary experience, such as one’s name or the existnece of one’s hands, is rather different from belief that observed phenomena explain unobserved phenomena. Yet, I certainly agree that we do hold fast to belief in many cicumstance, sometimes in the face of evidence to the contrary.
I will say in closing that there is evidence which suggests that something other than simple natural selection and adaptation might be part of the evolutionary process. As I indicated above, PE by Gould is likely a good place to begin.
Regards,
Timothy E. Kennelly