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