Editing Irreducible complexity (section)

=== Forerunners ===
The argument from irreducible complexity is a descendant of the [[teleological argument]] for God (the argument from design or from complexity). This states that complex functionality in the natural world which looks designed is evidence of an intelligent creator. [[William Paley]] famously argued, in his 1802 [[watchmaker analogy]], that complexity in nature implies a God for the same reason that the existence of a watch implies the existence of a watchmaker.<ref name="paley" /> This argument has a long history, and one can trace it back at least as far as [[Cicero]]'s ''[[De Natura Deorum]]'' ii.34,<ref>''On the Nature of the Gods'', translated by Francis Brooks, London: Methuen, 1896.</ref><ref>See [[Henry Hallam]] [https://books.google.com/books?id=FpDzTASTVwsC&pg=PA385 ''Introduction to the Literature of Europe in the Fifteenth, Sixteenth, and Seventeenth Centuries'' Boston: Little, Brown and Company, 1854] volume 2 page 385 part iii chapter iii section i paragraph 26 footnote ''u''</ref> written in 45 BC.

==== Up to the 18th century ====

[[Galen]] (1st and 2nd centuries AD) wrote about the large number of parts of the body and their relationships, which observation was cited as evidence for creation.<ref>''De Formatione Foetus''=''The Construction of the Embryo'', chapter 11 in ''Galen: Selected Works'', translated by P. N. Singer, ''The World's Classics'', Oxford, Oxford University Press, 1997 {{ISBN|978-0-19-282450-9}}. One 18th-century reference to Galen is [http://www.anselm.edu/homepage/dbanach/dnr.htm#A13 David Hume ''Dialogues Concerning Natural Religion'', 1779, Part 12]{{webarchive|url=https://web.archive.org/web/20051122134556/http://www.anselm.edu/homepage/dbanach/dnr.htm |date=2005-11-22 }}, §&nbsp;3, page 215. Also see Galen's ''De Usu Partium''=''On the Usefulness of the Parts of the Body'', translated and edited by Margaret Tallmadge May, Ithaca, New York, Cornell University Press, 1968, especially book XVII. For a relevant discussion of Galen and other ancients see pages 121–122, {{cite book |author= Goodman, Lenn Evan |title= Creation and evolution |location= Milton Park, Abingdon, Oxon and New York |publisher= Routledge |year= 2010 |isbn= 978-0-415-91380-5}}</ref> The idea that the interdependence between parts would have implications for the origins of living things was raised by writers starting with [[Pierre Gassendi]] in the mid-17th century<ref>''De Generatione Animalium'', chapter III. Partial translation in: Howard B. Adelmann, ''Marcello Malpighi and the Evolution of Embryology'' Ithaca, New York, Cornell University Press, 1966, volume 2, pages 811-812.</ref> and by [[John Wilkins]] (1614–1672), who wrote (citing Galen), "Now to imagine, that all these things, according to their several kinds, could be brought into this regular frame and order, to which such an infinite number of Intentions are required, without the contrivance of some wise Agent, must needs be irrational in the highest degree."<ref>John Wilkins, ''Of the Principles and Duties of Natural Religion'', London, 1675, book I, chapter 6, page 82 [https://quod.lib.umich.edu/e/eebo/A66053.0001.001/1:5.6?rgn=div2;view=fulltext Early English Books Online]</ref><ref>"The appeal to irreducible complexity goes back more than three centuries. To quote John Wilkins ...", [https://www.3quarksdaily.com/3quarksdaily/2019/02/darwin-does-devolve-sometimes-so-what.html Paul Braterman "Darwin Does Devolve. Sometimes. So What?" 3 Quarks Daily February 25, 2019]</ref> In the late 17th-century, [[Thomas Burnet (theologian)|Thomas Burnet]] referred to "a multitude of pieces aptly joyn'd" to argue against the [[eternity]] of life.<ref>[http://www.sacred-texts.com/earth/ste/ste07.htm ''The Sacred Theory of the Earth''] {{webarchive|url=https://web.archive.org/web/20071020060523/http://sacred-texts.com/earth/ste/ste07.htm |date=2007-10-20 }}, 2nd edition, London: Walter Kettilby, 1691. Book I Chapter IV page 43</ref> In the early 18th century, [[Nicolas Malebranche]]<ref>{{cite book|first= Nicolas|last= Malebranche|title= De la recherche de la verité: où l'on traite de la nature de l'esprit de l'homme, & de l'usage qu'il en doit faire pour éviter l'erreur dans les sciences|edition= 6ième|location= Paris|publisher= Chez Michel David|year= 1712|url= https://books.google.com/books?id=Gi0_AAAAcAAJ&q=%22d%C3%A9pendent%20mutuellement%22&pg=RA1-PA57}} Livre 6ième, 2ième partie, chapître 4; English translation: {{cite book|first= Nicholas|last= Malebranche|title= The Search After Truth: With Elucidations of The Search After Truth|editor1= Thomas M. Lennon |editor2= Paul J. Olscamp |location= Cambridge|publisher= Cambridge University Press|year= 1997|isbn= 978-0-521-58004-5|url= https://archive.org/details/searchaftertruth0000male|url-access= registration|page= [https://archive.org/details/searchaftertruth0000male/page/465 465]}} Second paragraph from the end of the chapter, on page 465.</ref> wrote "An organized body contains an infinity of parts that mutually depend upon one another in relation to particular ends, all of which must be actually formed in order to work as a whole", arguing in favor of [[preformation]], rather than [[epigenesis (biology)|epigenesis]], of the individual;<ref>Pages 202-204 of {{cite book|first= Andrew |last= Pyle |chapter= Malebranche on Animal Generation: Preexistence and the Microscope |editor= Smith JH |title= The problem of animal generation in early modern philosophy |publisher= Cambridge University Press |location= Cambridge, UK |year= 2006 |pages= 194–214 |isbn= 978-0-521-84077-4 |chapter-url= https://books.google.com/books?id=EyMWhGH4JgIC&q=%22irreducible+complexity%22+intitle%3Aproblem+intitle%3Aof+intitle%3Ageneration+inauthor%3Asmith&pg=PA204|author-link= Andrew Pyle (philosopher) }}</ref> and a similar argument about the origins of the individual was made by other 18th-century students of natural history.<ref>{{cite web|url=http://talkreason.org/articles/chickegg.cfm|title=The Chicken or the Egg|website=talkreason.org|access-date=7 May 2018|url-status=live|archive-url=https://web.archive.org/web/20170429075443/http://www.talkreason.org/articles/chickegg.cfm|archive-date=29 April 2017}}</ref> In his 1790 book, ''[[The Critique of Judgment#Teleology|The Critique of Judgment]]'', [[Immanuel Kant|Kant]] is said by Guyer to argue that "we cannot conceive how a whole that comes into being only gradually from its parts can nevertheless be the cause of the properties of those parts".<ref>This is Guyer's exposition on page 22 of {{cite book|editor= Paul Guyer|title= The Cambridge Companion to Kant|first= Paul|last= Guyer|author-link= Paul Guyer|chapter= Introduction|pages= [https://archive.org/details/cambridgecompani0000unse_i7u7/page/1 1–25]|location= Cambridge|publisher= Cambridge University Press|year= 1992|isbn= 978-0-521-36768-4|chapter-url= https://books.google.com/books?id=pYE5rVzrPNgC&q=%22gradually+from+its+parts%22+intitle%3Acambridge+intitle%3Acompanion+intitle%3Ato+intitle%3Akant+inauthor%3Aguyer&pg=PA22|url= https://archive.org/details/cambridgecompani0000unse_i7u7/page/1}} Guyer adds this parenthetical comment: "(here is where the theory of natural selection removes the difficulty)". See Kant's discussion in section IX of the "First Introduction" to the ''Critique of Judgment'' and in §§&nbsp;61, 64 (where he uses the expression ''wechselsweise abhängt''="reciprocally dependent"), and §&nbsp;66 of "Part Two, First Division". For example, {{cite book |chapter-url= https://books.google.com/books?id=JEXHIcDbBDcC&q=%22reciprocally+dependent%22+intitle%3Acritique+intitle%3Ajudgment+inauthor%3Akant&pg=PA243 |title= Critique of the power of judgment |first= Immanuel |last= Kant |editor1= Paul Guyer |editor2= Eric Matthews |location= Cambridge |publisher= Cambridge University Press |year= 2000 |isbn= 978-0-521-34447-0 |pages= 243–244 |chapter= §&nbsp;64 }} German original {{cite book |title= Kritik der Urtheilskraft |url= https://books.google.com/books?id=6O1Nayo3wWgC&q=akademie+%22wechselsweise+abhängt%22+inauthor:kant&pg=PA371 |volume= 5 |page= 371 |location= Berlin |publisher= Georg Reimer |edition= Königlich Preußischen Akademie der Wissenschaften |series= Kants gesammelte Schriften |year= 1913 |isbn= 978-3-11-001438-9 }}</ref><ref>See also {{cite book|title=Opus Postumum|url=https://archive.org/details/opuspostumumthec00kant|url-access=limited|first=Imanuel|last=Kant|editor=Eckart Förster|translator1=Eckart Förster|translator2=Michael Rosen|location=Cambridge|publisher=Cambridge University Press|year=1993|isbn=0-521-31928-5|page=[https://archive.org/details/opuspostumumthec00kant/page/n125 64]|quote=The definition of an organic body is that it is a body, every part of which is there ''for the sake of the other'' (reciprocally as end and, at the same time, means).}}German original {{cite book |title= Kritik der Urtheilskraft |url= https://books.google.com/books?id=6O1Nayo3wWgC&q=akademie+%22wechselsweise+abhängt%22+inauthor:kant&pg=PA371 |volume= 21 |page= 210|location= Berlin |publisher= Georg Reimer |edition= Königlich Preußischen Akademie der Wissenschaften |series= Kants gesammelte Schriften |isbn=978-3-11-090167-2|date = February 1971}}</ref>

==== 19th century ====
Chapter XV of Paley's ''Natural Theology'' discusses at length what he called "relations" of parts of living things as an indication of their design.<ref name="paley">[http://darwin-online.org.uk/content/frameset?itemID=A142&viewtype=text&pageseq=1 William Paley:''Natural Theology; or, Evidences of the Existence and Attributes of the Deity. Collected from the Appearances of Nature'' 12th edition, 1809] {{webarchive|url=https://web.archive.org/web/20080430030715/http://darwin-online.org.uk/content/frameset?itemID=A142&viewtype=text&pageseq=1 |date=2008-04-30 }}</ref>

[[Georges Cuvier]] applied his principle of the ''correlation of parts'' to describe an animal from fragmentary remains. For Cuvier, this  related to another principle of his, the ''conditions of existence'', which excluded the possibility of [[transmutation of species]].<ref>See especially chapters VI and VII of {{cite book|first= William |last= Coleman |title= Georges Cuvier, Zoologist: A Study in the History of Evolution Theory |url= https://archive.org/details/georgescuvierzoo0000cole |url-access= registration |location= Cambridge, Massachusetts |publisher= Harvard University Press |year= 1964}} See also the discussion of these principles in the Wikipedia article on [[Georges Cuvier|Cuvier]].</ref>

While he did not originate the term, [[Charles Darwin]] identified the argument as a possible way to falsify a prediction of the theory of evolution at the outset. In ''[[The Origin of Species]]'' (1859), he wrote, "If it could be demonstrated that any complex organ existed, which could not possibly have been formed by numerous, successive, slight modifications, my theory would absolutely break down. But I can find out no such case."<ref>[[Charles Darwin|Darwin, Charles]] (1859). ''[[The Origin of Species|On the Origin of Species]]''. London: John Murray. [http://darwin-online.org.uk/content/frameset?itemID=F373&viewtype=side&pageseq=207 page 189, Chapter VI] {{webarchive|url=https://web.archive.org/web/20070930011159/http://darwin-online.org.uk/content/frameset?itemID=F373&viewtype=side&pageseq=207 |date=2007-09-30 }}</ref> Darwin's theory of evolution challenges the teleological argument by postulating an alternative explanation to that of an intelligent designer—namely, evolution by natural selection. By showing how simple unintelligent forces can ratchet up designs of extraordinary complexity without invoking outside design, Darwin showed that an intelligent designer was not the necessary conclusion to draw from complexity in nature. The argument from irreducible complexity attempts to demonstrate that certain biological features cannot be purely the product of Darwinian evolution.<ref>See for example, {{cite book|first= Alan R.|last= Rogers|author-link=Alan R. Rogers|title= The Evidence for Evolution|location= Chicago|publisher= University of Chicago Press|year= 2011|isbn= 978-0-226-72382-2}} in pages 37–38, 48–49 citing Joseph John Murphy accepting natural selection within limits, excepting "the eye" with its multiple parts. {{cite news|first= Joseph John |last=Murphy|title= Presidential Address to the Belfast Natural History and Philosophical Society|journal= Northern Whig|location= Belfast|date= November 19, 1866|url= http://darwin-online.org.uk/content/frameset?viewtype=image&itemID=CUL-DAR226.1.118-119&pageseq=1|url-status= live|archive-url= https://web.archive.org/web/20120718161404/http://darwin-online.org.uk/content/frameset?viewtype=image&itemID=CUL-DAR226.1.118-119&pageseq=1|archive-date= July 18, 2012}} and in page 48 citing {{cite book|first=C. |last=Pritchard|author-link=Charles Pritchard|title=The Continuity of the Schemes of Nature and Revelation: A Sermon Preached, by request, on the occasion of the meeting of the British Association at Nottingham. With remarks on some relations of modern knowledge to theology|chapter=Appendix Note A On the Origin of Species by Natural Selection|year=1866|pages=31–37|location=London|publisher=Bell and Daldy|chapter-url=https://archive.org/details/continuityofsche00prit}}, especially page 33</ref>

In the late 19th century, in a dispute between supporters of the adequacy of [[natural selection]] and those who held for [[inheritance of acquired characteristics]], one of the arguments made repeatedly by [[Herbert Spencer]], and followed by others, depended on what Spencer referred to as ''co-adaptation'' of ''co-operative'' parts, as in: <blockquote>"We come now to Professor [[August Weismann|Weismann]]'s endeavour to disprove my second thesis—that it is impossible to explain by natural selection alone the co-adaptation of co-operative parts. It is thirty years since this was set forth in 'The Principles of Biology.' In §&nbsp;166, I instanced the enormous horns of the extinct [[Irish elk]], and contended that in this and in kindred cases, where for the efficient use of some one enlarged part many other parts have to be simultaneously enlarged, it is out of the question to suppose that they can have all spontaneously varied in the required proportions."<ref>Page 594 in: {{cite journal|first= Herbert|last= Spencer|title= Weismannism Once More|journal= [[The Contemporary Review]]|date= October 1894|volume= 66 |pages= 592–608}} Another essay of Spencer's treating this concept is: {{cite journal|first= Herbert |last= Spencer |title= The Inadequacy of "Natural Selection" |journal= The Contemporary Review |volume= 63 |year= 1893 |pages= 153–166}} (Part I: February) and pages 439-456 (Part II: March). These essays were reprinted in {{cite book|first= Herbert|last= Spencer|title= The Works of Herbert Spencer|year= 1891|place= London|publisher= Williams and Norgate|volume= 17}} (also Osnabrück: Otto Zeller, 1967). See also part III, Chapter XII, §&nbsp;166, pages 449-457 in: {{cite book |first= Herbert |last= Spencer |title= Principles of Biology |year= 1864 |place= London |publisher= Williams and Norgate|volume= I}} And: {{cite journal|journal= [[The Nineteenth Century (periodical)|The Nineteenth Century]] |first= Herbert|last= Spencer|title= The Factors of Organic Evolution |volume= 19 |year= 1886 |pages= 570–589}} (Part I: April) and pages 749-770 (Part II: May). "Factors" was reprinted in pages 389-466 of {{cite book|first= Herbert|last= Spencer|title= The Works of Herbert Spencer|volume= 13|location= London|publisher= Williams and Norgate|year= 1891}} (also Osnabrück: Otto Zeller, 1967)= volume 1 of ''Essays: Scientific, Political, and Speculative''.</ref><ref>One example of a response was in Section III(γ) pages 32-42 of {{cite book|first= August |last= Weismann |chapter= The Selection theory |pages= 19–65 |title= Darwin and Modern Science: Essays in Commemoration of the Centenary of the Birth of Charles Darwin and of the Fiftieth Anniversary of the Publication of The Origin of Species|chapter-url= https://archive.org/details/in.ernet.dli.2015.42056 |editor= [[Albert Seward]]|location= Cambridge |publisher= Cambridge University Press |year= 1909}} See also Chapter VII, §&nbsp;12(1), pages 237-238 in: {{cite book|first= J. Arthur |last=Thomson|title= Heredity|url= https://archive.org/details/in.ernet.dli.2015.217008|place= London|publisher= John Murray|year= 1908|author-link= J. Arthur Thomson}} Both of these referred to what has become known as the [[Baldwin effect]]. An analysis of both sides of the issue is: {{cite book |first= George John |last=Romanes |title= Darwin and After Darwin: Post-Darwinian Questions, Heredity, Utility |volume= II |chapter= III: Characters as Hereditary and Acquired (continued) |pages= 60–102 |place= London |publisher= Longman, Green |year= 1895|author-link= George John Romanes }}</ref></blockquote> Darwin responded to Spencer's objections in chapter XXV of ''[[The Variation of Animals and Plants Under Domestication]]'' (1868).<ref>{{cite book|title= The Variation of Animals and Plants Under Domestication|first= Charles|last= Darwin|year= 1868|location= London|publisher= John Murray|chapter= XXV. Laws of Variation ''continued'' – Correlated Variability|volume= 2|pages= 321–338|chapter-url= http://darwin-online.org.uk/content/frameset?keywords=co%20ordinated&pageseq=236&itemID=F877.2&viewtype=text|url-status= live|archive-url= https://web.archive.org/web/20150925075611/http://darwin-online.org.uk/content/frameset?keywords=co%20ordinated&pageseq=236&itemID=F877.2&viewtype=text|archive-date= 2015-09-25}} especially page 333 and following.</ref> The history of this concept in the dispute has been characterized: "An older and more religious tradition of idealist thinkers were committed to the explanation of complex adaptive contrivances by intelligent design. ... Another line of thinkers, unified by the recurrent publications of Herbert Spencer, also saw [[co-adaptation]] as a composed, irreducible whole, but sought to explain it by the inheritance of acquired characteristics."<ref>Pages 67-68 in: {{cite journal|first= Mark|last= Ridley|title= Coadapatation and the Inadequacy of Natural Selection|journal= British Journal for the History of Science |volume= 15|issue= 1 |date= March 1982 |pages= 45–68 |doi= 10.1017/S0007087400018938|pmid= 11610981|s2cid= 9704653|author-link= Mark Ridley (zoologist)}}</ref>

[[St. George Jackson Mivart]] raised the objection to natural selection that "Complex and simultaneous co-ordinations ... until so far developed as to effect the requisite junctions, are useless".<ref>{{cite book|title= On the Genesis of Species|url= https://archive.org/details/Mivart1871gk14P|first= St. George Jackson |last=Mivart|location= London|publisher= Macmillan|year= 1871|page= [https://archive.org/details/Mivart1871gk14P/page/52 52]|author-link= St. George Jackson Mivart}}</ref> In the 2012 book ''Evolution and Belief, Confessions of a Religious Paleontologist'', Robert J. Asher said this "amounts to the concept of 'irreducible complexity' as defined by ... Michael Behe".<ref>{{cite book|author= Asher, Robert J.|title= Evolution and belief: confessions of a religious paleontologist|location= Cambridge & New York|publisher= Cambridge University Press|year= 2012|isbn= 978-0-521-19383-2|page= 214}} See also Christian Faculty Forum at [[University of California, Santa Barbara|UCSB]], [http://www.veritas-ucsb.org/library/origins/quotes/irreducible.html Irreducible Complexity] {{webarchive|url=https://web.archive.org/web/20111018165943/http://www.veritas-ucsb.org/library/origins/quotes/irreducible.html |date=2011-10-18 }} and the references cited there.</ref>

==== 20th century ====
[[Hermann Joseph Muller|Hermann Muller]], in the early 20th century, discussed a concept similar to irreducible complexity. However, far from seeing this as a problem for evolution, he described the "interlocking" of biological features as a consequence to be expected of evolution, which would lead to irreversibility of some evolutionary changes.<ref name="Muller_1918">{{cite journal |author= Muller, HJ |title= Genetic variability, twin hybrids and constant hybrids, in a case of balanced lethal factors |journal= Genetics |volume= 3 |issue= 5 |pages= 422–99 |year= 1918 |doi= 10.1093/genetics/3.5.422 |url= http://www.genetics.org/cgi/reprint/3/5/422 |pmid= 17245914 |pmc= 1200446 |url-status= dead |archive-url= https://web.archive.org/web/20070518220445/http://www.genetics.org/cgi/reprint/3/5/422 |archive-date= 2007-05-18 |access-date= 2006-10-31 }}, especially pages 463–4.</ref> He wrote, "Being thus finally woven, as it were, into the most intimate fabric of the organism, the once novel character can no longer be withdrawn with impunity, and may have become vitally necessary."<ref>{{cite journal |author= Muller, HJ |title= Reversibility in evolution considered from the standpoint of genetics |journal= Biological Reviews of the Cambridge Philosophical Society |volume= 14 |issue= 3 |pages= 261–80, quotation from 272 |year= 1939 |doi=10.1111/j.1469-185x.1939.tb00934.x |s2cid= 85668728 }}</ref>

In 1975 [[Thomas H. Frazzetta]] published a book-length study of a concept similar to irreducible complexity, explained by gradual, step-wise, non-teleological evolution. Frazzetta wrote: <blockquote>"A complex adaptation is one constructed of ''several'' components that must blend together operationally to make the adaptation 'work'. It is analogous to a machine whose performance depends upon careful cooperation among its parts. In the case of the machine, no single part can greatly be altered without changing the performance of the entire machine."</blockquote> The machine that he chose as an analog is the [[Peaucellier–Lipkin linkage]], and one biological system given extended description was the jaw apparatus of a python. The conclusion of this investigation, rather than that evolution of a complex adaptation was impossible, "awed by the adaptations of living things, to be stunned by their complexity and suitability", was "to accept the inescapable but not humiliating fact that much of mankind can be seen in a tree or a lizard."<ref>T. H. Frazzetta, ''Complex Adaptations in Evolving Populations'', Sunderland, Massachusetts: Sinauer Associates, 1975. {{ISBN|0-87893-194-5}}. Referencing pages 3, 4-7, 7-20, and xi, respectively.</ref>

In 1985 [[Graham Cairns-Smith|Cairns-Smith]] wrote of "interlocking": "How can a complex collaboration between components evolve in small steps?" and used the analogy of the scaffolding called [[centring|centering]]—used to [[arch#Construction|build an arch]] then removed afterwards: "Surely there was 'scaffolding'. Before the multitudinous components of present biochemistry could come to lean together ''they had to lean on something else.''"<ref name="Cairns-Smith, A. G. 1985 https://archive.org/details/sevencluestoorig00cair_0/page/39 39, 58–64">{{cite book |author= Cairns-Smith, A. G. |title= Seven clues to the origin of life: a scientific detective story |publisher= Cambridge University Press |location= Cambridge, UK |year= 1985 |pages= [https://archive.org/details/sevencluestoorig00cair_0/page/39 39, 58–64] |isbn= 978-0-521-27522-4 |url= https://archive.org/details/sevencluestoorig00cair_0/page/39 }}</ref><ref>McShea, Daniel W. and Wim Hordijk. "[https://link.springer.com/article/10.1007%2Fs11692-013-9227-6 Complexity by Subtraction]." ''Evolutionary Biology'' (April 2013). [http://www.worldwidewanderings.net/Professional/Publications/complsub.pdf PDF] {{webarchive|url=https://web.archive.org/web/20130513010713/http://www.worldwidewanderings.net/Professional/Publications/complsub.pdf |date=2013-05-13 }}.</ref> However, neither Muller or Cairns-Smith claimed their ideas as evidence of something supernatural.<ref name="Perakh 2008">{{cite journal |url= http://www.skeptic.com/the_magazine/ |title= Bacteria Flagella Look Like Man-made Machines |first= Mark |last= Perakh |publisher= [[Skeptic (U.S. magazine)]] |year= 2008 |volume= 14 |issue= 3 |access-date= 2008-12-06 |url-status= dead |archive-url= https://web.archive.org/web/20081208185535/http://www.skeptic.com/the_magazine/ |archive-date= 2008-12-08 |author-link= Mark Perakh }}</ref>

An early concept of irreducibly complex systems comes from [[Ludwig von Bertalanffy]] (1901–1972), an Austrian biologist.<ref>Ludwig von Bertalanffy (1952). ''Problems of Life: An Evaluation of Modern Biological and Scientific Thought, pg 148'' {{ISBN|1-131-79242-4}}</ref> He believed that complex systems must be examined as complete, [[irreducibility|irreducible]] systems in order to fully understand how they work. He extended his work on biological complexity into a general theory of systems in a book titled ''[[systems theory|General Systems Theory]]''.

After [[James Watson]] and [[Francis Crick]] published the structure of [[DNA]] in the early 1950s, General Systems Theory lost many of its adherents in the physical and biological sciences.<ref>{{cite book |author= Monod, Jacques |title= Chance and necessity: an essay on the natural philosophy of modern biology |publisher= Vintage Books |location= New York |year= 1972 |isbn= 978-0-394-71825-5 |url= https://archive.org/details/chancenecessity00mono }}</ref>
However, [[systems theory]] remained popular in the social sciences long after its demise in the physical and biological sciences.