Evolution: Philosophically stupid.

DEFINITIONS { Limb: An appendage of a particular creature. My right leg is an example. This seems to be the definition my opponent is using. Feature: A specific quality which all members of a given species share. Types of limbs shared by all members of a species are examples. [ex: all fish have jaws, all humans have two hands with five fingers each, etc] Species: A set of interrelated creatures who share a specific set of qualities. *Note that this definition is very different than the definitions used to name species. Note also that under this species definition, in some cases creatures of different species could mate, where that is not possible by some other definitions. } . STATEMENT OF POSITIONS { My opponent's argument seems to be that it is impossible for evolution to cross the species barrier when we use this definition - that it is impossible for evolution to lead to new species with new features. It is my position that evolution is indeed capable of this. } . CONTENTION I: A Spheroid Example { Consider the case of an asexually reproducing spheroid creature. This creature does not have any limbs - it is very close in shape to a sphere. Consider that a mutation occurs during reproduction which creates a bump in the offspring. This bump would be a new limb, and thus the child would have a new feature that the parent did not have. Further mutations could occur which make the bump more noticeable, and evolution will likely lead to a larger bump eventually if the bump is useful to the creature - for instance, if it allows the creature to push off the ground more effectively. I'd like to ask my opponent if he thinks the process I have defined here cannot occur. } . CONTENTION II: Rarity, Nuance { My opponent contends that we should expect, if evolution is capable of producing new limbs, to have seen it at least every now and then. However, it is likely that the occurrence and success of new limbs is a very rare circumstance. We have not been observing and recording everything we've seen in the natural world for very long. New features likely don't come about very often, and they are often likely to be harmful, so they probably rarely survive very long for us to see. Further, given the very small portion of animals which we observe, it may be that it would actually be unlikely for us to have seen a new feature. Last of all, new features are likely very nuanced in appearance. In all cases where wings developed, they did not just suddenly exist as wings in the child. They usually started off just as slightly stretched skin between two bones, and they got more and more winglike as evolution progressed. We have noticed plenty of instances of skin being abnormally stretched between bones - webbed feet in human beings is a good example [II.1]. Unfortunately, "feature" is such an elusive word that it's unclear exactly where on the scale from webbing to wings we would say there's a new feature. For instance, do flying squirrels [See II.2 for clarification] have a feature that other members of the squirrel family lack? Do human with webbed toes? Do bats have a feature that all other mammals lack? If the evolution of a feature is done in small stages [like a wing], what specific criteria should be used to determine if a step entails a new feature? } [II.1] http://birthdayshoes.com... [II.2] http://en.wikipedia.org... . CONTENTION III: Very visible examples { We have seen instances of creatures with six fingers on a hand [III.1], two heads [III.2], etc. These are direct examples of a child having a different set of features than either parent. } [III.1] http://www.worldofstock.com... [III.2] http://www.oddee.com... . CONTENTION IV: The Burden of Proof { Evolution [even macroevolution] has a wealth of evidence behind it - not only fossil evidence, but also extremely solid genetic evidence [including IV.1]. It is accepted by the overwhelming majority of scientists, particularly those who work in biology [IV.2]. This stuff is direct evidence in my favor. Evidence and experts both indicate that my opponent's position is incorrect. We must consider my opponent's argument with these things in mind. He hasn't provided an argument as to why it couldn't happen - he's just noted that he doesn't think it could happen, and he's never seen it happen directly or indirectly. This would be an acceptable argument if it was made against a proposition for which there was no evidence, but my opponent is claiming that his lack of understanding outweighs the mountain of evidence in favor of common ancestry. However, I will still continue arguing for my side despite this. } [IV.1] "By plugging these sequences into various relational and evolutionary models, he found that a universal common ancestor is at least 10^2,860 more likely to have produced the modern-day protein sequence variances than even the next most probable scenario (involving multiple separate ancestors)" http://www.scientificamerican.com... [IV.2] "less than 0.15 percent of relevant scientists believe in creationism" - http://www.talkorigins.org... - [Statistics from Robinson 1995] . CONTENTION V: Jawless Fish { Not all fish have jaws. Some fish do not have jaws. While this would put them in a different species by the definition we're using, there is evidence that jaws began merely as mutations in jawless fish [V.1], supporting the notion that evolution can indeed create features. } [V.1] "It is thought that a gill arch in an agnathan [Jawless fish] became fused to its skull. The upper part of the gill support became the top jaw and the bottom part of the gill support became the bottom jaw. Embryology points to this and the arrangement of nerves in shark heads and most simple fishes shows that jaws are in line with gill arches." - http://serendip.brynmawr.edu... . CONCLUSION { That is all for now. I will allow my opponent to reply to my case, and perhaps even to provide a positive case for his assertion that evolution couldn't possibly have caused the development of features. }