Thursday, April 20, 2006

A rebuttal of circular reasoning

Claim: Scientists use circular reasoning when they are dating rock layers and fossils. Fossils are used to date the rock layers that are used to date the fossils that are used to date the layers... etc. Also, the principles of dating that rock layers and the fossils are based on the assumption that evolution is fact.

Rebuttal: When out in the field with no access to advanced dating equipment, paleontologists/geologists make relative dates of the layers based on their position relative to those [layers] above and below it (e.g. World War I was fought before World War II). Some of these layers can be tested later to obtain a more absolute date (WWI was fought between 1914-1918 and WWII was fought 21 years later). A lot of strata (ro
ck layers) are not dated accordingly by the fossils they contain and these methods of relative and absolute dating are self-sufficient.

Yet there are some particular fossils that occur only in specific strata. Called index fossils, they are typically widespread and very common. They are usually very easy to diagnose or distinguish and have a relatively short species duration that in turn gives those dating the rock a shorter span of time in which to make a relative date. When available, these fossils are very useful in making relative dates because of their correspondance with the strata layers that have already been previously dated by other means.

Lastly, the principles of stratigraphy and the naming and classification of the geological column was first ignited by the work of English geologist William Smith. Smith, who was the first to create a geological map of England, conducted most of his work between the 1790's and the early 19th century. Charles Darwin had not yet begun his voyage with the HMS Beagle until December of 1831. It was stratigraphy and William Smith's principle of faunal succession that influenced Darwin and his theory of evolution, not the other way around.

No comments: