Editing Intelligent design (section)

===Irreducible complexity===
{{Main|Irreducible complexity}}
[[Image:MichaelBehe.jpg|thumbnail|right|The concept of [[irreducible complexity]] was popularised by [[Michael Behe]] in his 1996 book, ''[[Darwin's Black Box]]''.]]
The term "irreducible complexity" was introduced by biochemist [[Michael Behe]] in his 1996 book ''[[Darwin's Black Box]]'', though he had already described the concept in his contributions to the 1993 revised edition of ''Of Pandas and People''.<ref name="pandafounds" /> Behe defines it as "a single system which is 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>{{cite web |url=http://www.apologetics.org/MolecularMachines/tabid/99/Default.aspx |title=Molecular Machines: Experimental Support for the Design Inference |last=Behe |first=Michael |author-link=Michael Behe |year=1997 |website=Apologetics.org |publisher=The Apologetics Group;[[Trinity College (Florida)|Trinity College of Florida]] |location=Trinity, Fla. |access-date=2014-02-28 |url-status=dead |archive-url=https://archive.today/20120801101947/http://www.apologetics.org/MolecularMachines/tabid/99/Default.aspx |archive-date=August 1, 2012 }} "This paper was originally presented in the Summer of 1994 at the meeting of the C.S. Lewis Society, Cambridge University."</ref>

Behe uses the analogy of a mousetrap to illustrate this concept. A mousetrap consists of several interacting pieces—the base, the catch, the spring and the hammer—all of which must be in place for the mousetrap to work. Removal of any one piece destroys the function of the mousetrap. Intelligent design advocates assert that natural selection could not create irreducibly complex systems, because the selectable function is present only when all parts are assembled. Behe argued that irreducibly complex biological mechanisms include the bacterial flagellum of ''[[Escherichia coli|E. coli]]'', the [[Coagulation|blood clotting cascade]], [[Cilium|cilia]], and the adaptive [[immune system]].<ref>Irreducible complexity of these examples is disputed; see {{cite court |litigants=Kitzmiller v. Dover Area School District |vol=04 |reporter=cv |opinion=2688 |date=December 20, 2005}} [[s:Kitzmiller v. Dover Area School District#4. Whether ID is Science]] pp. 76–78, and [[Kenneth R. Miller]]'s January 3, 2006, lecture at [[Case Western Reserve University]]'s Strosacker Auditorium, {{YouTube|id=Ohd5uqzlwsU|title="The Collapse of Intelligent Design: Will the Next Monkey Trial be in Ohio?"}}.</ref><ref>{{cite web |url=http://www.millerandlevine.com/km/evol/design2/article.html |title=The Flagellum Unspun: The Collapse of 'Irreducible Complexity' |last=Miller |first=Kenneth R. |website=Biology by Miller & Levine |publisher=Miller and Levine Biology |location=Rehoboth, Mass. |access-date=2014-02-28}} "This is a pre-publication copy of an article that appeared in 'Debating Design from Darwin to DNA,' edited by [[Michael Ruse]] and William Dembski."</ref>

Critics point out that the irreducible complexity argument assumes that the necessary parts of a system have always been necessary and therefore could not have been added sequentially.<ref name="reducibly complex mousetrap, Ussery" /> They argue that something that is at first merely advantageous can later become necessary as other components change. Furthermore, they argue, evolution often proceeds by altering preexisting parts or by removing them from a system, rather than by adding them. This is sometimes called the "scaffolding objection" by an analogy with scaffolding, which can support an "irreducibly complex" building until it is complete and able to stand on its own.<ref group="n">{{cite journal |last1=Bridgham |first1=Jamie T. |last2=Carroll |first2=Sean M. |last3=Thornton |first3=Joseph W. |author-link3=Joseph Thornton (biologist) |date=April 7, 2006 |title=Evolution of Hormone-Receptor Complexity by Molecular Exploitation |url=https://www.science.org/doi/abs/10.1126/science.1123348 |journal=[[Science (journal)|Science]] |volume=312 |issue=5770 |pages=97–101 |bibcode=2006Sci...312...97B |doi=10.1126/science.1123348 |pmid=16601189 |s2cid=9662677 |access-date=2014-02-28|url-access=subscription }} Bridgham, ''et al.'', showed that gradual evolutionary mechanisms can produce complex protein-protein interaction systems from simpler precursors.</ref>
In the case of Behe's mousetrap analogy, it has been shown that a mousetrap can be created with increasingly fewer parts and that even a single part is sufficient.<ref name=":0">{{Cite web |last=McDonald |first=John H. |date=2002 |title=A reducibly complex mousetrap |url=https://udel.edu/~mcdonald/oldmousetrap.html |url-status=live |archive-url=https://web.archive.org/web/20140222041104/http://udel.edu/~mcdonald/mousetrap.html |archive-date=2014-02-22 |access-date=2024-11-14 |website=University of Delaware}}</ref>

Behe has acknowledged using "sloppy prose", and that his "argument against [[Darwinism]] does not add up to a logical proof."<ref group="n">[[#Orr 2005|Orr 2005]]. This article draws from the following exchange of letters in which Behe admits to sloppy prose and non-logical proof:
*{{cite web |url=http://www.discovery.org/a/1406 |title=Has Darwin Met His Match? – Letters: An Exchange Over ID |last1=Behe |first1=Michael |author-link1=Michael Behe |last2=Dembski |first2=William A. |last3=Wells |first3=Jonathan |author-link3=Jonathan Wells (intelligent design advocate) |last4=Nelson |first4=Paul A. |author-link4=Paul Nelson (creationist) |last5=Berlinski |first5=David |author-link5=David Berlinski |date=March 26, 2003 |website=[[Center for Science and Culture]] |publisher=[[Discovery Institute]] |location=Seattle |type=Reprint |access-date=2014-02-28}}</ref> Irreducible complexity has remained a popular argument among advocates of intelligent design; in the [[Kitzmiller v. Dover Area School District|Dover trial]], the court held that "Professor Behe's claim for irreducible complexity has been refuted in [[Peer review|peer-reviewed]] research papers and has been rejected by the scientific community at large."<ref name="Kitzmiller v p. 64" />