Dembski begins by analyzing
signs from
God in the
Bible, and notes that such signs have
specificity and
complexity, which enables them to be clearly discernible. He considers this to be a general insight regarding recognition of the "Divine Finger", and states, "My aim in this book is to take this
premodern logic of signs and make it rigorous." A review of
naturalistic criticisms of miracles, particularly those by
Benedict Spinoza and
Friedrich Schleiermacher, follows. Dembski critiques the critiques, and derides the
methodological naturalism that, he says, is part of their legacy. He then focuses on the history of
natural theology in Britain, recounting the
teleological arguments of
William Paley and
Thomas Reid, and the primary reason for their demise, the Darwinian theory of evolution by
natural selection. Upon introducing it, Dembski immediately criticizes it and commends the critique of
Charles Hodge, who he says argued that Darwinism "was trying to subsume intelligent causation under physical causation." Intelligent design, the central idea of the book, is then introduced. He distinguishes it from
theistic evolution and, especially, purely naturalistic evolution. Explaining a motivation for it, he states, "Darwinism is the totalizing claim that [natural selection] accounts for all the diversity and complexity of life. The evidence simply does not support this claim.... [There] is always a temptation in science [to] think that one's theory encompasses a far bigger domain than it actually does." He lists numerous phenomena that he claims have proven to be "utterly intractable" for natural selection, including the origin of life, the origin of the
genetic code, and the
Cambrian explosion. Then comes the technical theory. He introduces his
complexity-specification criterion, which states that in order to infer design, three criteria must be met simultaneously: contingency, complexity, and specification. According to Dembski, the first rules out necessity; the latter two rule out chance. Combined with his
universal probability bound of 10−150, he claims that this criterion is completely accurate when applied to actual objects "with known underlying causal story." Dembski derives what he purports to be an instance of what
Peter Medawar (in 1984) identified as the
law of conservation of information. However mathematician
Jeffrey Shallit has rebutted this claim, stating that "Medawar’s 'law' is not the same as Dembski’s" in that Medawar "makes no mention of probabilities or the name Shannon", and that "Medawar’s law, by the way, can be made rigorous, but in the context of
Kolmogorov information, not
Shannon information or Dembski’s '
complex specified information'." Dembski then introduces the term "complex specified information" (CSI), and claims that CSI is indicative of design. He considers whether the only known natural mechanisms of
physical law and
chance, alone or in combination, can generate such information, and concludes that they cannot. He argues that this is so because laws can only shift around or lose information, but do not produce it, and chance can produce complex unspecified information, or unspecified complex information, but not CSI; he provides a mathematical analysis that he claims demonstrates that law and chance working together cannot generate CSI, either. Moreover, Dembski claims that CSI is
holistic (with the whole being greater than the sum of the parts, and that this decisively eliminates Darwinian evolution as a possible means of its creation. He then enumerates the possible sources of CSI in biological organisms:
inheritance,
selection, and
infusion. He states that the first two sources are "unable to account for the CSI in biological systems (and specifically for the
irreducible complexity of certain biochemical systems...)", and therefore concludes that CSI must come from infusion. He further argues that biotic infusion cannot ultimately account for CSI, and so abiotic infusion must be the source. Dembski maintains that by process of elimination, CSI is best explained as being due to
intelligence, and is therefore a reliable indicator of
design. He implies that his theory can be useful in several fields, including
forensic science,
intellectual property law,
archaeology, and the
search for extraterrestrial intelligence. Dembski concludes the book with comments on what he sees as the theological implications of intelligent design. In an appendix, he offers answers to various objections to intelligent design. ==Reception==