Congratulations to all of those Darwinists who seek to exclude ID from science whenever the CSI in a structure or DNA sequence is difficult to quantify exactly. You’ve just excluded a highly influential form of evolutionary analysis (cladistics) from science as well. The following lengthy quote is from Adrain, Jonathan M.; Edgecombe, Gregory D. & Lieberman, Bruce S., Fossils, Phylogeny, and Form: An Analytical Approach, New York: Kluwer Academic (2002), pp 56-57:
Phylogenetic inference is pivotal to an understanding of the systematics of any group. Cladistics offers an objective framework for the analysis of data that inevitably incorporates elements of subjectivity (Hennig 1966, Swofford 1993). A cladogram is a hypothesis of relationships derived from a set of putatively homologous morphological and/or molecular characters (Forey 1992), to which is added information on character polarity or the nature of an outgroup. If homologous organs or characters are defined as those jointly inherited from a common ancestor (Simpson 1961, Hennig 1966), it becomes impossible to identify homologies without access to the true phylogeny (a problem of circularity: Jardine and Sibson 1971). Hence, criteria of compositional and structural similarity are used in practice. Compositional similarity refers to resemblance in terms of biological or chemical constituents (the composition of the organs). Structural correspondence refers to the spatial or temporal arrangement of parts, structure of biochemical pathways, or the sequential arrangement of organized structures (Sneath and Sokal 1973). The number of potential characters is limited only by our ability to recognize putative homologies at increasingly fine scales.
Inevitably, even the most rigorous tests of homology can fail to identify character states that are similar because of convergence or ‘reversal’ (‘homoplasy’, rather than direct, common descent). Most real data sets therefore contain character conflict (Strauch 1984, Deleporte 1993). This is usually resolved using some optimality criterion (e.g., parsimony) to derive one or more cladistics hypotheses (which will reject some fraction of the supposed homologies).
Various types of data and analytical techniques are employed in cladistics, sometimes yielding widely differing results (Wiley 1981). Nonetheless, there is consensus on the nature of the pattern being sought, and the objective reality of the process that produced it (cladogenesis). There is only one true evolutionary tree, and the diversity of approaches therefore all have the same ultimate goal (Wilkinson 1992). Inevitably, the process of selecting characters for analysis is subjective, and amounts to a radical form of character weighting (Meacham 1994, Wilkinson 1994a). The sample is also likely to be biased towards more obvious features, and frequently towards those with some form of historical precedence (Pearson 1999).
The absence of complete objectivity at all stages in a cladistics analysis in no sense detracts from its value in producing hypotheses of relationships. Other (non-cladistic) approaches in systematics also operate on finite data sets and incorporate similar assumptions. Often, these do not produce hypotheses directly, but serve to describe aspects of the data, frequently offering additional insights into evolutionary processes (Foote 1996). All results (phylogenetic and otherwise) should therefore be presented along with the original data and sufficient information to all the analysis to be repeated.
Let’s count up the subjective judgments that go into constructing a cladogram. I see at least the following (there are almost certainly more).
- Which characters am I going to select for analysis?
- Are these structures homologous?
- Is there “resemblance” of biological or chemical constituents?
- Are the spatial and temporal arrangement of parts similar?
- Are the character differences upstream or downstream?
- Homology or Homoplasy?
- Is there “structural correspondence”?
No wonder different scientists’ analyses yield “wildly differing results.”
Consider the following sentence extracted from the quotation above:
The absence of complete objectivity at all stages in a cladistics analysis in no sense detracts from its value in producing hypotheses of relationships.
Is the following a fair extrapolation of the authors’ logic:
The absence of complete objectivity at all stages in a ID analysis in no sense detracts from its value in producing hypotheses of design.