Fundamental to the argument of many Darwinists against intelligent design theory in biology is the assertion that design in biology is undetectable. Darwinists argue that biological design is undetectable because, while we have experience with ‘designers’ in archeology, forensic science, etc., we have no experience with designers in biology, and thus cannot reliably detect the work of a biological designer. Intelligent design proponents reply that there are reliable criteria that indicate design, regardless of whether we have actual knowledge of the designer.

Without doubt, the detection of design is of primary importance in many fields of science, such as archeology, forensic science, cryptography, and bioterrorism. And the detection of design is at least theoretically possible even if we have no experience with the designer. The design inference is the scientific basis for the Search for Extraterrestrial Intelligence, in which investigators search for signal patterns that imply intelligent agency amid the dense background of naturally occurring signals in the cosmos. Despite our lack of experience with extraterrestrial intelligence, we assume, reasonably, that we could detect at least some design in signals sent from intelligent agents.
In the field of archeology, a remarkable discovery has shed light on the scientific validity of the inference to design when we have no knowledge of the designer. In 1900, divers exploring a 1st century B.C. shipwreck off the Greek island of Antikythera found a coral-encrusted device the size of a small laptop computer that was clearly part of the 2000 year-old ship’s cargo. Further examination of this device, called the Antikythera mechanism, including x-ray and CT studies, shows it to be a remarkable assembly of precisely designed gears. Many scientists believe that it was a device for predicting eclipses and planetary motion, but its precise function is still a mystery. Its resemblance to an analog computer is striking (an x-ray image is shown above). Archeologists believe that the technology to produce such a device didn’t emerge until at least the 14th century A.D. They have no evidence as to who designed it, and no evidence even of who could have designed it. Yet the inference to design is obvious, and no archeologist doubts that it is a designed artifact. Design can be inferred from an artifact alone, regardless of the obscurity or the implausibility of a designer.
Living things are full of nanotechnology that greatly exceeds the complexity and the specificity of the Antikythera mechanism. In any other field of science, such technology would be recognized as the product of intelligent design. The Darwinian mechanism of random mutation and natural selection has never been shown experimentally to be capable of producing such remarkable specified complexity. Although the philosophical implications of the design inference in biology are profound in comparison with the implications of the design inference in the Antikythera mechanism, we can infer design in both situations. The reverse engineering approaches to studying the Antikythera mechanism can be applied to biology as well.
Although we have no direct scientific knowledge of the designers of either the Antikythera mechanism or of the nanotechnology in living cells, the inference to design, by analogy to modern human design, is reasonable and is valid scientific methodology.