Friday, February 8, 2013

The teleology of DNA replication

Jonathan M. at Evolution News and Views has a great post on the extraordinary complexity and purpose manifest in DNA replication. He quotes from a 1998 paper in Cell:

Synthesis of all genomic DNA involves the highly coordinated action of multiple polypeptides. These proteins assemble two new DNA chains at a remarkable pace, approaching 1000 nucleotides (nt) per second in E. coli. If the DNA duplex were 1 m in diameter, then the following statements would roughly describe E. colireplication. The fork would move at approximately 600km/hr (375 mph), and the replication machinery would be about the size of a FedEx delivery truck. Replicating the E. coli genome would be a 40 min, 400 km (250 mile) trip for two such machines, which would, on average make an error only once every 170 km (106 miles). The mechanical prowess of this complex is even more impressive given that it synthesizes two chains simultaneously as it moves. Although one strand is synthesized in the same direction as the fork is moving, the other chain (the lagging strand) is synthesized in a piecemeal fashion (as Okazaki fragments) and in the opposite direction of overall fork movement. As a result, about once a second one delivery person (i.e. polymerase active site) associated with the truck must take a detour, coming off and then rejoining its template DNA strand, to synthesize the 0.2km (0.13 mile) fragments.
To which Darwinists reply: DNA replication manifests no evidence for teleology, no evidence for intelligence, no evidence for design, and no purpose at all.



  1. Michael,

    DNA replication doesn't show any evidence of intelligent design. E. coli divides so rapidly that often replication of the entire circular chromosome isn't complete before the two daughter cells have separated.

    As a result, the size of the E. coli genome can vary by up to 30% and many important genes can be lost.

    Unlike eukaryotic cells, bacterial genomes contain very little junk DNA, and the genes themselves don't contain introns, the segments of genes not translated into protein - which have to be spliced out - and which make up to at least 95% of large genes. So the 30% variation isn't just due to variations in the amount of junk DNA.

    All is not lost if important genes are lost. Missing genes can be regained from fellow bacteria through horizontal gene transfer via donation of plasmids (an example of kin altruism in bacteria).

    Rapid multiplication of bacteria is their competition strategy. The faster a bacterium can divide in times of feast, the more of its descendants will be present when the inevitable famine occurs. And the more that will be present to take advantage of a feast when it returns.

    The function of DNA replication is reproduction. If there is purpose involved in the process, then it's in the reason why DNA replication is often incomplete, with the loss of genes. And the reason would be that rapid division is more important in competition than complete replication of the genome.

    Teleology could only be said to exist in E. coli DNA replication if the replication process was more complex than necessary (like having a complex 4-chamber heart in an earthworm instead of its simple muscular tube). And it isn't. In comparison to DNA replication and transcription in eukaryotic cells, bacteria are extremely simple.

    Teleology is a directed process. There's a target. Some feature has to be present not needed now, but to meet some future set of circumstances not currently existing.

    If a feature is currently being used and is important, it's not a teleological feature. It's an adaptation.

    1. Shorter Dr. Egnor:

      It's complicated. Therefore, God.


    2. @Hoo:

      If you'll notice, my arguments aren't to complexity per se. Throwing a deck of cards up in the air yields a complex array of cards on the floor. That's not the kind of purpose we see in biology.

      I argue to directedness and purpose. And you have no meaningful answer.

    3. Directedness I agree with. Purpose, however, is in the eye of the beholder. It boils down to intent of a maker, which you cannot prove unless you confirm it directly with him.

      Humans are notoriously biased to anthropomorphize nature. You are no exception.


    4. @Hoo:

      [Purpose, however, is in the eye of the beholder. It boils down to intent of a maker, which you cannot prove unless you confirm it directly with him.]

      So, until you have a conversation with God, you don't know the purpose of the eye?

    5. @Hoo:

      [Directedness I agree with.]

      Directedness means tending to a state that does not yet exist. Where does the directedness come from? How can an inanimate/unintelligent thing be directed, unless by a intelligence?

    6. Egnor: So, until you have a conversation with God, you don't know the purpose of the eye?

      Function, yes. Purpose, no.

      God may have meant eyes to be a favorite snack for lions. Or something.


    7. Egnor: Directedness means tending to a state that does not yet exist. Where does the directedness come from? How can an inanimate/unintelligent thing be directed, unless by a intelligence?

      Crystal growth represents a directed process: a crystal increase in size, rather than decreases. It does not mean that the process is directed by someone. It does break the time reversal symmetry, though.


    8. @Hoo:

      A growing crystal does not "know" the future. It's inanimate. How does it grow in a directed fashion. Who directs it?

      Is this one of those atheist "shit happens" things?

    9. Exactly. What's your theory? Are angels involved? :)


    10. And what does this theory tell us, Dr. Egnor? Can it be put to practical use?


    11. It's put to practical use everyday everywhere by all biologists. The inference to purpose is essential to biology. Most biological research involves discerning the purpose of things. "Function" is too non-specific to guide research-- things have innumerable functions (the DNA in my gluteus maximus functions to help insulate by butt in the winter)but inference to purpose allows us to discern functions that are important (genetics) from those that are unimportant (butt insulation).

      The ENCODE scandal demonstrates how important it is to understand purpose in biology. 80% of DNA is functional-- the big question is: how much of it serves a purpose?

    12. Could you first address crystals? How does your theory help us better understand crystal growth?


    13. Teleology is implicitly assumed in studying the growth of crystals.

      If natural processes don't tend to specific ends, how do you know that a crystal will grow?

      As for purpose, it is generally not readily discernable in inanimate things, unlike living things.

    14. Dr. Egnor,

      What use is any of that to scientists studying crystals?


    15. I'll type slowly as I repeat myself.

      Scientists implicitly presume teleology. If there weren't a directedness in nature, there would be no reason to think that certain experimental conditions would consistently produce crystals. Without teleology, adding sugar to hot water and cooling it might produce a butterfly, or nuclear fission, or an aardvark.

      You intuitively understand and depend upon teleology in nature, even if you're too ideologically blinkered to admit it.

    16. Dr. Egnor,

      There is no point in typing slowly. You are simply not answering a question I asked. So here it is again.

      Scientist 1 is an atheist. Scientist 2 is a Thomist who thinks that God is the Prime Mover responsible for crystal growth. What advantage does Scientist 2 have over Scientist 1? Can we study crystal growth without assuming that God is the Prime Mover? What will we miss if we don't assume that?


    17. Michael,

      ENCODE showed that between 20 and 80% of the human genome to be functional to the extent of being replicated at least once.

      How much has an important function (or purpose if you insist) is not clear at the moment. It will be considerably less that your repeated assertion that almost all of the human genome will have a function, let alone an important function.

      For a start, there are the tens of thousands of broken non-functional pseudogenes (such as half of the thousand olfactory receptor protein genes), the 800,000 or so SNPs (single nucleotide polymorphisms) which are free to mutate (and provide a very useful marker for family studies and detecting disease associated genes, if the particular SNP occurs close enough to the gene) and the huge number of transposons, which act as viral remnants).

      I suspect the answer will turn out to be around 10%. Why would 90% of the human genome not have an important function? It's been suggested that since eukaryotic cells are huge (in comparison to bacteria), they need huge nuclei. So the nucleus is stuffed with filler; DNA without an important function. The nuclei have to be large to give space and time to allow the splicing out of the segments in mRNA molecules corresponding to the introns in genes (which in large genes make up at least 95% of the gene).

      Bacterial genes don't have introns. The bacterial chromosome also doesn't have much junk DNA. Bacteria also don't have nuclei. Bacteria evolved to be 'lean and mean', dropping genes readily because of their rapid reproduction. Bacteria are the perfect example of Darwinian evolution, as shown by Lenski's research on E. coli.

      You're still confused as to the meaning of 'teleology'. It's not an 'end' as occurs in a process such as crystal formation or DNA replication. There's no 'directness to an end in a change', because there's no 'change'.

      In DNA replication, there's no 'change'. All that's happened is that you finish up with two copies of exactly the same DNA molecule.

      DNA replication isn't evidence of your beloved Thomistic (teleological) evolution. Evolution by definition is change in species. DNA replication isn't 'changing', so it's not teleological.

      The only way that you could determine that teleological mechanisms are occurring in evolution is to find a species, any species, that has a feature more complex than necessary for survival. Can you think of any examples?

      DNA replication, no matter how complex, isn't evidence of teleology. It's just an adaptation.

    18. @Hoo:

      [Scientist 1 is an atheist. Scientist 2 is a Thomist who thinks that God is the Prime Mover responsible for crystal growth. What advantage does Scientist 2 have over Scientist 1? Can we study crystal growth without assuming that God is the Prime Mover? What will we miss if we don't assume that?]

      Both scientists use the inference to teleology. No difference in application.

      Scientist 2 logically thinks it through. Scientist 1 refuses to think it through, and mocks and persecutes Scientist 2. He thinks that Scientist 2's ideas are so dangerous and idiotic that they should be banned in public schools. Scientist 1 calls Scientist 2 a creationist, a fundie, and and IDiot.

      Scientist 2 gets pissed off, and starts his own blog, where he challenges Scientist 1 to a fair public debate.

      Scientist 1 says really stupid things ('the heart has no purpose...), and looks like a fool.

      Scientist 2 is happy.

    19. @bach:

      [ENCODE showed that between 20 and 80% of the human genome to be functional to the extent of being replicated at least once. How much has an important function (or purpose if you insist) is not clear at the moment.]

      You're right. Most of the genome is functional-- it is transcribed. But does most of the genome have a purpose? That's a very important question.

      Function and purpose are not the same thing. Both are real.

    20. Aside from the silly public debates, what impact does Thomistic thinking could have on research in crystal growth. I contend none.

      Crystal growth is a process that is well described by statistical mechanics. God's intent, or lack thereof, is irrelevant to it. One can be an atheist crystal grower, or one who is a devout Christian, and be equally successful in the endeavor.

      Now, I don't discount that a Thomist might find some interesting inspiration in crystal growth and describe it on his own terms. But that description does not tell scientists how to grow better crystals. It is just mental masturbation that is harmless and could relieve some stress.


    21. Michael,

      The amount of DNA in humans that is transcribed at least once could be as little as 20%. That's not 'most'.

      You're confusing Aquinas' description of teleology in 'Summa Theologica' of an archer shooting an arrow at a distant target.

      That's clearly a metaphor. Confusing a metaphor with a real event is a sign of serious mental illness (I wonder what your explanation of 'people in glasshouses shouldn't throw stones' means).

      In teleology:

      The arrow hitting the bullseye isn't an endpoint.

      Crystal formation in a supersaturated solution isn't an endpoint.

      Formation of a new DNA molecule from an old one in DNA replication isn't an endpoint.

      Unless you insist on introducing theology into science by insisting that 'God is the ground of existence' and nothing happens without his permission.

    22. @Hoo:

      Western science arose in a civilization informed by Thomism, and only in that civilization.

      The influence of the Thomist understanding of nature/psychology/politics/law is so profound in Western civilization that people who are unreflective often fail to see it. They don't realize that most of their basic presuppositions are Thomist in origin.

      It's like a fish swimming in water, who doesn't notice the water.

      Only where Thomism (and Christianity) flourished has modern theoretical science emerged. Other great empires-- China, India, African civilizations, New World civilizations-- never originated genuine modern science.

      Science as we know it today-- theories about nature verified by the scientific method-- is a Thomist/Christian project.

      It's a shame that so many of the half-educated technicians who claim to be scientists don't even understand where science came from.

    23. History of science is a fascinating topic, Dr. Egnor. However, it has nothing to do with the question I asked.

      One more time and I give up: How does the Thomistic perspective help better understand crystal growth? What insights (interesting to a crystal grower, not a Thomist) does it provide?

      My answer is none. You have provided no refutation of that.


    24. How does the alphabet help a novelist?

      The very terms and ideas scientists use are Thomist (a bastardized version) in origin. If you really don't think that teleology is true, you have no reason to recognize or study natural laws, which are manifestations of teleology (and formal cause).

      You don't need to think explicitly about teleology in order to do science, but a roughly Thomist view of nature (material and efficient causes exist, and formal and final causes are implicitly recognized) is the predicate for modern science.

    25. Thomism is the alphabet and the grammar of modern science. But you can do science without paying any explicit attention to Thomism, just like you can write a novel without paying any explicit attention to the alphabet and grammar.

      You remind me of a kid who complains to his teacher about having to learn the times tables or grammar, arguing that he doesn't see anyone as a grownup having to know that stuff.

      But the reality is that Thomism (in its modern truncated form) is the grammar of science. You just don't notice it while you're doing it.

    26. Aha, this is now getting better.

      So even if I have no idea about Aristotle and Thomas and just get my physics degree at a secular university, just studying science, I can practice my science as well (or even better*) than my counterpart at Notre Dame who digs deeply into Thomas? Is that right?

      *He will have less time to spend on science because of the Thomist classes he must attend.


    27. Sure. You can be a cipher and do what you're told. That's what technicians do.

      What a real philosophical understanding of the underpinnings of science (natural philosophy) provides is an opportunity to think for yourself, and to make deeper insights into your discoveries in nature.

      Studying philosophy and developing a degree of comfort with Aristote/Thomas is like studying the liberal arts in ancient Rome. It was meant for free men, who were allowed to think for themselves.

      Slaves need not understand the underpinnings of their work.

    28. No disagreement here. Philosophy can be personally rewarding etc. Same goes for studies of history. But that is beside the point.

      The question we are discussing is different. Does having the Thomistic perspective help one be a better scientist? How would it help one better understand crystal formation? Quantum electrodynamics? Friction on the nanoscale?

      Can you answer these simple questions, Dr. Egnor? You have studiously avoided them.


    29. I've answered them repeatedly.

      An explicit understanding of philosophy/Thomism is unnecessary to ordinary science.

      An implicit utilization of Thomistic concepts (causation, hylemorphism, teleology, four causes, etc) is an absolute prerequisite for modern science.

      Whether you understand where your presumptions come from is another matter.

      For example, Heisenberg noted that some of the "strangeness" of quantum mechanics is the result of our adaptation of a truncated Aristotelian understanding of nature, as a result of Newton's work. We had come to recognize only material and efficient cause as active in nature. Heisenberg saw that formal and especially final cause seemed to show up in the quantum world, especially in non-locality (final cause).

      He also noted that the collapse of the quantum waveform was a remarkable vindication of Aristotle's view of potency and act. A quantum state entails a probabilistic array of "potencies" which are reduced to actuality "act" with collapse of the waveform.

      Another example would be the obvious application of teleology to evolution. Rather than a mechanical process of random variation and survival of survivors, one can understand evolution as a teleological process and dump the banalities and tautologies.

    30. Michael,

      And teleological evolution reduces to 'survivors survive'.

      That is:

      Survivors (if God wills in a new structure or function, or an improved structure or function, in a species to deal with future changed conditions not currently existing - by unknown mechanism and for unknown reasons)

      survive (unless God decides for unknown reasons not to favor the species with teleology to cope with future changed circumstances, in which it goes extinct, like 99.9% of previous species).

      A banal triviality. And a tautology.

      DNA replication isn't evidence of teleology. It's just a process which has existed unchanged for billions of years. Evidence of 'design' perhaps, but not teleology.

    31. Egnor: An explicit understanding of philosophy/Thomism is unnecessary to ordinary science.

      Ah, very good. Thank you, Dr. Egnor. I would slightly change the wording and use the word irrelevant, rather than unnecessary, but this is a minor nit to pick.

      Egnor: For example, Heisenberg noted that some of the "strangeness" of quantum mechanics is the result of our adaptation of a truncated Aristotelian understanding of nature, as a result of Newton's work.

      Heisenberg was a lone voice among physicists who thought that a return to philosophical roots might explain the strangeness of quantum mechanics. The prevailing viewpoint is that it is not so much quantum mechanics that is strange but rather that the microscopic world is the way it is. Our intuition, based on our experience in a macroscopic world with its classical physics, is of little help in understanding it.

      Non-locality has nothing to do with final causes. It is an instantaneous change in the wavefunction of a distant object when you perform a measurement on another object entangled with it. The non-locality is not real: one cannot effect a physical change instantaneously over a large distance, and the rule of quantum mechanics work out in such a way that no change is physically observed. The non-locality only happens in our description of objects, in the form of wavefunction collapse. A wavefunction, however, is not a measurable quantity. Thus there is no physical non-locality, just an illusion of one.

      The description in terms of a wavefunction is probably not the last word in quantum mechanics. One thing for sure: it won't be fixed by philosophers, whether Aristotelean, Thomistic, or Kantian.


    32. @Hoo:

      [The description in terms of a wavefunction is probably not the last word in quantum mechanics. One thing for sure: it won't be fixed by philosophers, whether Aristotelean, Thomistic, or Kantian.]

      Science is natural philosophy. We're all philosophers, Hoo. The difference is that some of us know we are, and some don't. And some philosophy is good and some isn't. You can't escape philosophy.

    33. Michael,

      No, we are not all philosophers, in the sense that everyone loves wisdom. A lot of people are just plain incurious as to how the Universe works, instead trying to replace real understanding with a fictional Prime Mover, meaning that it's no longer necessary to attempt to come to a real understanding.

      It's just a science stopper.

      There's good philosophy and bad philosophy. And Aristotelean and Thomistic philosophy are just bad philosophy. They don't add anything and they're just a hindrance.

  2. bachfiend, I don't know why you keep misrepresenting what teleology actually is. This is nonsense:
    "Some feature has to be present not needed now, but to meet some future set of circumstances not currently existing."

    DNA replication is teleological. I.e. the natural end of the DNA machinery is to duplicate DNA. Simple really. You can evel apply it to sub-components:

    Helicases are known to be ring-shaped (typically hexamers) motor proteins. DNA replication occurs at about 1000 base pairs per second. In the cell, DNA forms a double helix. However, during DNA replication in a cell helicases unwind DNA. They unwind DNA at about the same speed that DNA replication occurs. Simply put, the natural end of helicase is to unwind DNA.

    More here:

    1. Adm. G Boggs, Glenbeckistan NavyFebruary 8, 2013 at 9:53 AM

      Techne, I think you will find that Johann (aka backfield) is not misrepresenting teleology. He simply misunderstands it. Invoke Hanlon's Razor.

    2. Technetium and Georgie,

      I do understand teleology. I'm just applying Egnor's definition he provided in the last thread.

      Teleology: the directness to an end of a change.

      There is no change occurring in the DNA replication in E. coli. It's the same process in all bacteria. It has been occurring for billions of years.

      No change. Therefore no directness. You can't infer directness unless the process is changing in a direction not necessary today but will be necessary tomorrow to meet circumstances not presently existing and not foreseen.

      You're confusing the process of DNA replication with teleology. It's not the series of steps resulting in a replicated DNA molecule that's teleology.

      That (according to Egnor's definition in the same thread) is a function.

      Function: participation in a causal change.

      He also includes his definition of purpose and intention.

      Purpose: the meaning that is imparted by an intentional act.

      Intention: the capacity of a thought to refer to something other than itself; loosely, to ascribe meaning.

      There. Have a laugh at Egnor's definitions. He doesn't even apply them consistently. He refers to DNA being 80% functional, at least to the extent that ENCODE has shown that between 20 and 80% of the human genome is replicated at least once. No causal chain involved in the function of DNA replication. No result from most of the DNA replication.

    3. Bachfiend, it appears you are still confused as to what teleology actually is. It is pretty straightforward, “every agent acts for an end”. Replication is a teleological process and has been going on for billions of years. The natural end of replication machinery (i.e. agent in this example) is to make copies of DNA. See, it is an easy concept to grasp.

    4. Techne,

      Well, that makes Michael's teleological evolution meaningless. Evolution is the change in a species over time. If the mechanism of DNA replication doesn't change over time (and neither you, nor Georgie, nor Michael have produced any evidence that it has), then DNA replication isn't evidence of teleological evolution.

      DNA replication is possibly evidence of ID (I don't think so) as an example of design.


    5. Lol, the mechanism of DNA replication doesn't need to change over time for the process of DNA replication itself (and its associated mechanism) to be teleological. The process itself and the associated mechanism are teleological as pointed out many times, including the OP. Your continued misunderstanding of the concept of teleology won't change that.

    6. Techne,

      I wouldn't be interested in teleology if it wasn't for Egnor using it to justify something he calls teleological evolution. Hearts pump blood, eyes see, DNA replication mechanisms generate new copies of DNA molecules... It's so trivial, it's banal.

      It's just a function of a system.

      Michael uses it to 'support' teleological evolution. Evolution is change in a species over time. God has a target in mind as to what a species will look like in the future, and causes the appropriate change in the species now. The changed species is the endpoint. No matter how complex DNA replication is, unless it changes, it's not evidence for teleological evolution.

    7. bachfiend, you don't need to adhere to "teleological evolution e.g. front-loaded evolution or think evolution has some sort of specific target in the future to notice and accept and accept that every agent acts for an end. Evolution is not an agent, it is a process, so if it does not act for an end... so what?

    8. Techne:

      [Evolution is not an agent, it is a process, so if it does not act for an end... so what?]

      Excellent point.

    9. Michael,

      'Excellent point'.

      So how does that support teleological evolution? And how do you recognize that teleological evolution ever occurs?

      DNA replication just shows that DNA replication is complex. Nothing more.

  3. I've just had an epiphany (while walking the dog).

    I've suddenly realized where Egnor, Techne and Georgie have gone wrong.

    They've basically taken Thomas of Aquinas' description for teleology of an archer shooting an arrow at a distant target as being literally true.

    It's clearly a metaphor. The endpoint of a teleological process isn't the bullseye on a target.

    Confusing a metaphor for a real event is a sign of serious mental illness, such as early dementia.

    Personally, I invoke Heinlein's Law; don't assume malice when stupidity is a better explanation - but don't dismiss malice.

    DNA replication could only be used as evidence of teleology if the process is being observed to be changing in a species and it can be determined that the change is being directed by an outside agent. Otherwise, DNA replication is just 'evidence' of 'design' (as demonstrated by Egnor getting his thread from the Discovery Institute website, not exactly a hotbed of Thomistic evolution. I personally don't think that it's evidence of design, but that's another matter.

    The process of DNA replication has never been observed to have changed. It's not a practical method. My suggested method is practical; just find one example of a feature more complex than necessary for survival in at least species and you will have some evidence at least consistent with teleology. An inference. Not definite.

    Any examples?

    1. The human mind.

      What benefit to survival is there to contemplating Thomism while watching your dog defecate?

    2. Michael,

      LOL. 'What benefit to survival is there to contemplating Thomism while watching your dog defecate'.

      Actually, it should have been 'what benefit to survival in watching your dog while contemplating Egnor defecating (mentally) Thomism'.

      Having a good laugh from time to time is good for general health.

      The mind is a product of the brain. It's a model of the outside reality and the individual's place in the reality.

      It's an illusion. A very useful one, but one which can be fooled. Including detecting agency (such as gods) when they don't exist. And giving the illusion that decisions are made consciously, instead of subconsciously and later rationalized.

      The human mind has been extremely useful throughout all of human evolution in keeping track of social interactions in bands of up 150 humans, keeping a tally of altruism versus selfishness on the part of other members of the group.

      Contemplating Thomism (or better expressed, engaging in mental masturbation) is just a spandrel on the mind. Not important.

      You still haven't responded to my comment that the process of DNA replication isn't evidence of teleology. Design perhaps (although I don't think so), but not teleology.

      You've confused the metaphor of the archer shooting an arrow at a distant target with something real. Crystals forming in a supersaturated solution just mean that physicochemical laws will give the same results in repeated experiments.

      Not a directed endpoint. Just an indication that there are underlying principals occurring in reality which will result in the same results when repeated.

      Science looks for the underlying principals.

    3. Argh!,

      Auto spellcheck 'principles' not 'principals'.

    4. Lol, this question from you bachfiend just again confirms you don't actually grasp the concept of teleology: "My suggested method is practical; just find one example of a feature more complex than necessary for survival in at least species and you will have some evidence at least consistent with teleology."

      You don't need "a feature more complex than necessary for survival" for a process to be teleological. This straw man question is as a result of your inability to understand what teleology is. Seriously, what is so difficult about it?

    5. Techne,

      OK. I don't have any objection to the statement that 'the function of the DNA replication system is to produce more copies of the DNA molecule'.

      I also don't have any objection to replacing 'function' with either 'purpose' or 'teleological endpoint', provided they have the identical meaning.

      I do object to using a word in a limited manner and then expanding its meaning. It's a sort of bait-and-switch.

      Another example would be to claim that the function of the brain is to think (actually, one of its functions - and you can argue what exactly 'thinking' is). And then extend it and claim that the purpose of the brain is to think about God. And the teleological endpoint of evolution is to produce humans with brains capable of thinking of God.

      OK. The teleological endpoint of DNA replication is the production of more copies of DNA molecules. It's trivial and banal.

    6. Function is not the same thing as purpose.

      Function is participation in a cause and effect cascade.

      Purpose is the particular function that characterizes the end to which the organ acts or points-- its teleology.

      The eye has many functions-- filling the eye socket, connecting the ophthalmic artery circulation to the ophthalmic vein circulation, seeing, expressing beauty or emotion, giving the extra-ocular muscles something to pull on, etc.

      It has one purpose-- seeing.

      A crack in the ground has many functions-- a sink for water, a place for insects to hide, a place to stumble on, etc.

      Yet it has no discernible purpose, no end to which it points.

    7. Michael,

      No, you've got it around the wrong way. The function of the eye is seeing. It's got only one function. It's purpose can vary. Including seeing reality. Or not. Purpose is intentional.

      A crack in the ground can serve a purpose - it can serve as a refuge for an insect if it wants one.

      I thought you were the one who insists nothing exists without God's will. According to you, a crack in the ground exists by God's will and its purpose exists by God's will.

      Although, in reality, purposes exist through the intention of those making use of them.

  4. Purpose is not only a future goal or potential that one must be able to discern from the initial set of conditions and structures. For example, if I build a house with the purpose of sheltering myself, once it is built and I shelter myself in the house it is fulfilling its purpose in the present. Purpose inherent in biology does not necessitate some future goal. As another example, we may say accurately that the eye has a purpose, ant that is for seeing. This is especially true for biology, because biological structures only survive if they meet several specific criteria, and if the environment doesn't radically change. So when considering something such as an eye, eyes only exist because life evolved sight. Moreover, in biology, existing structures that perform one function are not used primarily for some other function. For instance, no organism grows or evolves eyes that are fully functioning, but the organism instead uses them to walk with rather than see. As a result the eye evolved for seeing. The only reason the eye evolved was as a process of increasingly capable sense, and specifically increasingly capable sense of sight. In this way life is entirely purposive. This becomes even more evident when considering evolution, DNA, and the life process as a whole. Without appealing to any transcendental purpose, life as a whole only lives, and performs all of its functions for the purpose of living. This is not a projection humans have made. Purpose is not only in the eye of the beholder. There is true knowledge, and we can truly know things, purpose being included. If this is not the case, then science is a sham, because it claims to know in one instance, but then says that knowledge is not possible in another. But that is a different topic. Regarding purpose, all organisms, unless they are sick or in distress, attempt to survive. Life in general lives to survive and flourish. This is an inherent purpose. All organisms sense and react to the environment, the reaction of which is to continue living. Those reactions are therefore aimed at that end. Not all organisms are successful at surviving, as not all students who take a test actually pass. But all students who are actually taking the test, rather than attempting some other goal, are trying to pass, whether they actually pass or not. In the same way all life is trying to live, it may not live very long, and may not reproduce, but as long as it is alive, the living organism is achieving that goal, i,e, staying alive. because living organisms try to live, they put forth effort to live, their actions and behavior can be said to be for the purpose of survival, and this is truly accurate. Moreover, when considering evolution, the changes that evolution describes are changes that occur in the living process. So the evolved structures are the result of the living process, the process of attempting to survive and flourish. All successful evolutionary changes, are therefore bound in the same purpose, and each successful evolutionary change is successful because that change aided and increased survival and flourishing. Evolutionary changes that survive, then, do so because those changes were better at fulfilling that purpose.

  5. What I'm interested in is the fact that the atheist critics of teleology argue against the proponents of Thomism--calling it "mental masturbation" and whatever--as if the Thomists have violated some rule that dictates how they "ought" to act.

    How would the atheists defend the assumption that some chemical robots "ought" to reject teleology? Why "ought" they do anything? So some chemical robots believe in teleology? So? What objective law has been violated?