Changes

=Could we make this about Flagellum?==

==Could we make this about Flagellum?==

This article does not give any information about the flagellum function or structure but instead seems to be a soapbox about intelligent design and counters to it.  Very unproductive if you ask me.--[[User:Tims|TimS]] 14:31, 4 May 2007 (EDT)

This article does not give any information about the flagellum function or structure but instead seems to be a soapbox about intelligent design and counters to it.  Very unproductive if you ask me.--[[User:Tims|TimS]] 14:31, 4 May 2007 (EDT)

=The flagellum and the argument for Intelligent Design=

==The flagellum and the argument for Intelligent Design==

The flagellum has frequently been presented as a counter-example to evolution. <ref>Dembski, W. 2002a, No Free Lunch: Why specified complexity cannot be purchased without intelligence. Lanham, Maryland: Rowman & Littlefield.</ref> <ref>Behe, M. 1996a. Darwin's Black Box. New York: The Free Press.</ref> Anti-evolutionists argue that it could not possibly have been produced by an evolutionary pathway.   

The flagellum has frequently been presented as a counter-example to evolution. <ref>Dembski, W. 2002a, No Free Lunch: Why specified complexity cannot be purchased without intelligence. Lanham, Maryland: Rowman & Littlefield.</ref> <ref>Behe, M. 1996a. Darwin's Black Box. New York: The Free Press.</ref> Anti-evolutionists argue that it could not possibly have been produced by an evolutionary pathway.   

==The argument from irreducible complexity==

===The argument from irreducible complexity===

The flagellum is said to possess "irreducible complexity," meaning it could not have been produced by evolution. This argues for an outside intelligent designer operating beyond the laws of nature. Behe defines an irreducibly complex structure as ". . . a single system composed of several well-matched, interacting parts that contribute to the basic function, wherein the removal of any one of the parts causes the system to effectively cease functioning." <ref>Behe, M. 1996a. Darwin's Black Box. New York: The Free Press.</ref>  

The flagellum is said to possess "irreducible complexity," meaning it could not have been produced by evolution. This argues for an outside intelligent designer operating beyond the laws of nature. Behe defines an irreducibly complex structure as ". . . a single system composed of several well-matched, interacting parts that contribute to the basic function, wherein the removal of any one of the parts causes the system to effectively cease functioning." <ref>Behe, M. 1996a. Darwin's Black Box. New York: The Free Press.</ref>  

The argument is that because a minimum number of protein components are needed for a working biological function, evolution could not have selected to produce those components a few at a time, since they do not have functions that natural selection would favor.  The logic of irreducible complexity dictates that these individual components should have no function until all 30 are put into place, at which point the function appears. Behe wrote: " . . . natural selection can only choose among systems that are already working" <ref>Behe, M., 2002. The challenge of irreducible complexity, Natural History 111 (April): 74.</ref>. An irreducibly complex system does not work unless all of its parts are in place. The flagellum is irreducibly complex, and therefore it must have been designed.  

The argument is that because a minimum number of protein components are needed for a working biological function, evolution could not have selected to produce those components a few at a time, since they do not have functions that natural selection would favor.  The logic of irreducible complexity dictates that these individual components should have no function until all 30 are put into place, at which point the function appears. Behe wrote: " . . . natural selection can only choose among systems that are already working" <ref>Behe, M., 2002. The challenge of irreducible complexity, Natural History 111 (April): 74.</ref>. An irreducibly complex system does not work unless all of its parts are in place. The flagellum is irreducibly complex, and therefore it must have been designed.  

==Counter arguments to the argument from irreducible complexity==

===Counter arguments to the argument from irreducible complexity===

The argument for intelligent design has received many detailed rebuttals have appeared in scientific literature <ref>Coyne, J. A., 1996. God in the details, Nature 383: 227-228.</ref><ref> Miller, K. R. 1999. Finding Darwin's God. New York: Harper Collins</ref><ref> Depew, D. J. (1998), Intelligent design and irreducible complexity: A rejoinder. Rhetoric and Public Affairs 1: 571-578.</ref><ref> Thornhill, R. H., and D. W. and Ussery, 2000. A classification of possible routes of Darwinian evolution, The Journal of Theoretical Biology 203: 111-116</ref> including counter-examples to the assertion that evolution cannot explain biochemical complexity. <ref>Miller, K. R. 1999. Finding Darwin's God. New York: Harper Collins.</ref> Researchers have also investigated the means by which evolutionary mechanisms allow biological systems to increase in information content <ref>Schneider, T.D. (2000), Evolution of biological information. Nucleic Acids Research 28: 2794-2799.</ref> <ref>Adami, C., C. Ofria, and T. C. Collier, 2000. Evolution of biological complexity, Proceedings of the National Academy of Sciences 97: 4463—4468</ref>

The argument for intelligent design has received many detailed rebuttals have appeared in scientific literature <ref>Coyne, J. A., 1996. God in the details, Nature 383: 227-228.</ref><ref> Miller, K. R. 1999. Finding Darwin's God. New York: Harper Collins</ref><ref> Depew, D. J. (1998), Intelligent design and irreducible complexity: A rejoinder. Rhetoric and Public Affairs 1: 571-578.</ref><ref> Thornhill, R. H., and D. W. and Ussery, 2000. A classification of possible routes of Darwinian evolution, The Journal of Theoretical Biology 203: 111-116</ref> including counter-examples to the assertion that evolution cannot explain biochemical complexity. <ref>Miller, K. R. 1999. Finding Darwin's God. New York: Harper Collins.</ref> Researchers have also investigated the means by which evolutionary mechanisms allow biological systems to increase in information content <ref>Schneider, T.D. (2000), Evolution of biological information. Nucleic Acids Research 28: 2794-2799.</ref> <ref>Adami, C., C. Ofria, and T. C. Collier, 2000. Evolution of biological complexity, Proceedings of the National Academy of Sciences 97: 4463—4468</ref>

It is self-contradictory to argue that one irreducibly-complex system might contain another. The flagellum cannot be irreducibly complex if it contains a smaller functional set of components like the TTSS.

It is self-contradictory to argue that one irreducibly-complex system might contain another. The flagellum cannot be irreducibly complex if it contains a smaller functional set of components like the TTSS.

==The Combinatorial argument==

===The Combinatorial argument===

William Dembski <ref>Dembski, W. 2002a, No Free Lunch: Why specified complexity cannot be purchased without intelligence. Lanham, Maryland: Rowman & Littlefield. </ref> calculated the probability of assembling an object like the flagellum by working out the probabilities that each of its components might have originated, been localized to the same region of the cell, and assembled in the right order by chance.

William Dembski <ref>Dembski, W. 2002a, No Free Lunch: Why specified complexity cannot be purchased without intelligence. Lanham, Maryland: Rowman & Littlefield. </ref> calculated the probability of assembling an object like the flagellum by working out the probabilities that each of its components might have originated, been localized to the same region of the cell, and assembled in the right order by chance.

Dembski states that, given enough time, any event with a probability larger than 10_-150 might well take place. He puts the odds of evolving the 30 proteins of the bacterial flagellum at 20_-30 ("around 10_-39")  and explains that since the flagellum requires 30 such proteins, they "will all need to be multiplied to form the origination probability", which would give an origination probability for the flagellum of 10 _-1170. This is well below the universal probability bound, demonstrating that the flagellum could not have evolved.

Dembski states that, given enough time, any event with a probability larger than 10_-150 might well take place. He puts the odds of evolving the 30 proteins of the bacterial flagellum at 20_-30 ("around 10_-39")  and explains that since the flagellum requires 30 such proteins, they "will all need to be multiplied to form the origination probability", which would give an origination probability for the flagellum of 10 _-1170. This is well below the universal probability bound, demonstrating that the flagellum could not have evolved.

==Counter arguments to the Combinatorial argument==

===Counter arguments to the Combinatorial argument===

Dembski's calculation considers only the probability of spontaneous, random assembly for each of the proteins of the flagellum. His conclusion that the flagellum is unevolvable fits with his view that "The Darwinian mechanism is powerless to produce irreducibly complex systems...".

Dembski's calculation considers only the probability of spontaneous, random assembly for each of the proteins of the flagellum. His conclusion that the flagellum is unevolvable fits with his view that "The Darwinian mechanism is powerless to produce irreducibly complex systems...".

He assumed that none of the 30 proteins of the flagellum could have biological activity. We can see from the work on the TTSS that this is wrong. Nearly a third of those proteins are closely related to components of the TTSS, which does indeed have biological activity.  This seems to invalidate the underlying assumption of his calculations.  

He assumed that none of the 30 proteins of the flagellum could have biological activity. We can see from the work on the TTSS that this is wrong. Nearly a third of those proteins are closely related to components of the TTSS, which does indeed have biological activity.  This seems to invalidate the underlying assumption of his calculations.  

==References==

===References===

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