Godspell Follies

Refuting the illogic of "intelligent design" and creationism. An illustrated guide to fallacies of logic.

Recapitulating recapitulation

A short form for 'evolutionary development', Evo Devo is a branch of biology that addresses the interface between evolution and development of individuals (ontogeny).

Ernst Haeckel's (1866) formulation that 'ontogeny recapitulates phylogeny' is not accepted by modern biologists. His observations were accurate, his theoretical explanation (biogenetic law) is no longer accepted.

Ontogeny is the embryologic developmental process of individuals within a species, and phylogeny is the evolutionary history of that species. However, there is ample evidence that recapitulation does occur in so far as vertebrate embryos do resemble one another. This is the phenomenon in which a developing organism passes through (recapitulates) a similar attribute to that of an ancestral species. Fish are on the evolutionary tree of which Homo sapiens are a branch, yet we humans do not pass through a stage of being fish even though we do resemble fish embryos early in our embryological development.
"The embryonic vertebrate, at every stage, is an undeveloped and imperfect vertebrate, it can represent no adult animal whatever." *

The theoretical explanation accepted by most evolutionary biologists incorporates a variation on von Baer's hypothesis, that embryos develop from the most general features of the organism to the more specific. Differences appear over developmental time as species-specific elements form on a general vertebrate core.

The fact that literal interpretation of Haeckel's theory of recapitulation (biogenetic law) has been discredited is employed by creationists in an illogical attempt to discredit evolutionary theory. Creationists fail to distinguish the fundamental difference between an observation and the theory that explains that observation. Such attempts are illogical because Haeckel's formulation was merely a stage through which biological understanding passed. Attempts to discredit modern theory by citing theories discredited by modern science fail on the grounds that they are implied fallacies of composition. The fact that some earlier theories have been discarded does not mean that current theories ought to be discarded.

Such arguments may have emotional appeal to those who fear that science discredits their belief in biblical literacy and the Creator in Genesis. The point here, of course, is that emotionality is not logic-based. Rather, emotionality employs rationalization, which is an intellectualization intended to justify emotionally attractive beliefs.

Read an evolutionary biologist on this topic : Once more into the Haeckelian morass; or, Peter Moore is an illiterate fool

Part 13 of AronRa's Foundational Falsehood of Creationism series:

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Blogger qtr said...

The comment section will be used as a glossary, obviating some of the need to move around the site. If the website’s name shows as blue, you can return to the main page by clicking on “Godspell Follies” or “Home”.

idism = intelligent design theory
idist = intelligent design proponent, for example Behe or Dembski
fodi = fellow of the Discovery Institute, one of the organizations set up for the purpose of promoting intelligent design theory
proid = advocate of intelligent design theory, often an Internet debater

For a full explanation of these terms, see the Illogical Deceit Theory post at: http://refutingid.blogspot.com/2007/12/illogical-deceit-theory.html

5:24 PM  

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