ufacture of stone tools has been observed and replicated, as has the design and manufacture of sculptures such as Mount Rushmore. In archaeology, real design events are reconstructed in detail, including the time, location, materials, tools, techniques, motivation, and culture that produced an artifact, and these, in addition to basic physical laws that humans must follow such as conservation of mass, result in a highly constrained explanatory hypothesis that is readily testable with additional data. ID offers none of this. It invokes an unidentified, unconstrained agent (the intelligent designer) who makes complex biological structures such as the bacterial flagellum for an unknown purpose, using unknown techniques and unknown materials. Even questions such as the time of origin and whether or not mass and energy were conserved remain unanswered. ID provides none of the information that we have about human artifacts and their creators that allow us to make the decision that a given object is artificial rather than occurring naturally (Wilkins and Elsberry, 2001).
ID proponents regularly analogize machines (truly “purposeful arrangements of parts”) with multipart molecular structures and processes. Yet, on inspection, such analogies break down. The differences between biological phenomena and human-built machines easily outweigh the superficial similarities. Machines and other artifacts serve human purposes, whereas biological designs serve only the ultimate “purpose” of self-replication. Machines made by humans consist of parts designed for the task; complex biological “machines” are always, upon investigation, found to be cobbled together from preexisting modules with other functions. Biological designs are not really “purposeful arrangements of parts,” they are really adaptations of parts originally used for some other purpose. Some differences are even more fundamental. As Woese (2004) notes, “The machine metaphor certainly provides insights, but these come at the price of overlooking much of what biology is. Machines are not made of parts that continually turn over, renew. The organism is.” Woese suggests that organisms are like eddies in a current, “resilient patterns in a turbulent flow—patterns in an energy flow” (Woese, 2004).
ID proponents contend that scientists reject ID for religious/ philosophical reasons, allegedly to promote a materialistic worldview (Johnson, 1991). But as this discussion shows, ID has been rejected for its scientific failings. Its negative arguments against evolution are based on a strawman version of evolutionary theory and ignorance about the data and the literature. Its positive argument approaches the problem of biological design from an erroneous premise of an inaccurate analogy. Living things may be composed of individual parts, and may be highly complex, but they are not artifact-like in any way that would help explain their origins. Scientists who have examined claims of ID reject it because ID does not adequately explain the natural world. Significantly, these