Why intelligent design isn't science
Why intelligent design isn't science
Seattle PI on this topic, Krugman on ID, Chronicle of Higher Ed on ID, Letter to editor

Living organisms are complex. Their origin is beyond human experience. William Paley's "argument from design" has immediate appeal. His analogy of the watch (complex entity) and watchmaker (designer) is problematic. We know that watches are designed and how watchmakers design them. On the other hand we have no direct evidence that living organisms are designed and we have neither direct evidence for a designer nor, assuming one exists, evidence for how the design process works. One could substitute "magic" for "design" with no loss of insight.

Phillip Johnson, one of the fathers of the intelligent design (ID) movement said:
"What I noticed in 1987, was that Darwinism and evolution were more in my field, legal analysis, than in science. The amount of biology you have to know to argue it is very slim. It was mainly a matter of assumptions and logic."
Johnson, a lawyer, overlooks that science is (profoundly) more than logic. Explanatory mechanisms and experimental evidence are crucial to science. Science doesn't "prove" as in Aristotelian logic, but gives best explanations for natural phenomena. ID, the notion that life contains design input, is logically and philosophically legitimate. It fails on the scientific side. We have no evidence for a designer and no idea how a presumed designer works. For evolution we have evidence of mutation and selection. We understand mechanisms, at least partially. These mechanisms make testable predictions many of which (thousands at least) have been confirmed. Is evolution sufficient? There's no evidence for sufficiency, but insufficiency isn't evidence for additional processes.

Absence of mechanism and absence of testable hypotheses exclude ID from science. ID is like plate tectonics in the early 20th century. It was plausible, but lacked an established mechanism; so geologists ignored it. The discovery of sea floor spreading confirmed plate tectonics. Before carrying the analogy too far, bear in mind that plate tectonics made testable predictions even before the mechanism was established. In contrast to ID there were, from the beginning, plausible mechanisms.

Early proponents of ID made much of "information". William Dembski proposed the "law of conservation of information". This was recognizable (by physical chemists and molecular biologists) nonsense. Dembski now realizes this, but the notion of "information" as an independent entity still permeates ID.

Scientific literature shows evolution to be a highly productive theory. So far ID has produced only a few controversial papers in (very) obscure journals. The absence of clear theory, testable predictions and fruitful scientific literature are (highly) problematic for ID.