Editing Irreducible complexity (section)

=== The mousetrap example ===
[[File:Mausefalle 300px.jpg|thumb|200px|[[Michael Behe]] believes that many aspects of life show evidence of design, using the [[mousetrap]] in an analogy disputed by others.<ref name="trap">{{Cite web |last=McDonald |first=John H. |date=2002 |title=A reducibly complex mousetrap |url=https://udel.edu/~mcdonald/mousetrap.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 uses the mousetrap as an illustrative example of this concept. A mousetrap consists of five interacting pieces: the base, the catch, the spring, the hammer, and the hold-down bar. All of these must be in place for the mousetrap to work, as the removal of any one piece destroys the function of the mousetrap. Likewise, he asserts that biological systems require multiple parts working together in order to function. Intelligent design advocates claim that natural selection could not create from scratch those systems for which science is currently unable to find a viable evolutionary pathway of successive, slight modifications, because the selectable function is only present when all parts are assembled.

In his 2008 book ''[[Only A Theory]]'', biologist [[Kenneth R. Miller]] challenges Behe's claim that the mousetrap is irreducibly complex.<ref name=Only /> Miller observes that various subsets of the five components can be devised to form cooperative units, ones that have different functions from the mousetrap and so, in biological terms, could form functional [[spandrel (biology)|spandrels]] before being adapted to the new function of catching mice. In an example taken from his high school experience, Miller recalls that one of his classmates<blockquote>...struck upon the brilliant idea of using an old, broken mousetrap as a spitball catapult, and it worked brilliantly.... It had worked perfectly as something other than a mousetrap.... my rowdy friend had pulled a couple of parts—probably the hold-down bar and catch—off the trap to make it easier to conceal and more effective as a catapult... [leaving] the base, the spring, and the hammer. Not much of a mousetrap, but a helluva spitball launcher.... I realized why [Behe's] mousetrap analogy had bothered me. It was wrong. The mousetrap is not irreducibly complex after all.<ref name=Only>{{cite book |title= Only A Theory |url= https://archive.org/details/onlytheory00kenn |url-access= limited |first= Kenneth R. |last= Miller |location= New York |year= 2008 |publisher= Viking Penguin |pages= [https://archive.org/details/onlytheory00kenn/page/54 54]–55 |isbn= 978-0-670-01883-3}}</ref></blockquote>

Other systems identified by Miller that include mousetrap components include the following:<ref name="Only" />
*use the spitball launcher as a tie clip (same three-part system with different function)
*remove the spring from the spitball launcher/tie clip to create a two-part key chain (base + hammer)
*glue the spitball launcher/tie clip to a sheet of wood to create a clipboard (launcher + glue + wood)
*remove the hold-down bar for use as a toothpick (single element system)

The point of the reduction is that—in biology—most or all of the components were already at hand, by the time it became necessary to build a mousetrap. As such, it required far fewer steps to develop a mousetrap than to design all the components from scratch.

Thus, the development of the mousetrap, said to consist of five different parts which had no function on their own, has been reduced to one step: the assembly from parts that are already present, performing other functions.