"X only gives birth to its kind" is an invalid argument against Evolution

So lets start with initial statement: "No matter how many times it is tried, a dog only gives birth to dogs. Kinds beget their own Kind" While this statement is pretty simple, it is used in three seperate ways to argue against evolution. I plan to cover all three, and demonstrate how each of them fall foul to a particular logical fallacy as highlighted in my original three statements. As it is not often clarified by the person making the statement, most of what I present here is interpretation of what the person means, and is normally based only on my experience of arguing with creationists. If there is a more appropriate interpretation that may opponent wishes to use, please feel free, and I will rebut that also. X only gives birth to it's kind: For evolution to be true; an organism must be able to give birth or produce offspring that is not the same species. This interpretation implies that because one species diverges into another, there must be some point where parent and child are different species. This is the simplest interpretation to discount. Divergence of species is not at an invidual level. Each organism will produce offspring that are almost but not quite the same as the parent; over many generations these differences accumulate (this is effectively what evolution is). After a number of generations, an organism maybe very different from an ancestral form, yeilding a new species; but at no point through the chain is any organism a different species from the parent, as they differ only by a small amount. This is an example of misunderstanding gradualism. Primarily down to the categorisation of life. The very term species doesn't work very well at the individual nature; the term itself applies to a collection of organisms that are all the same; but in a changing, evolving system where things can change; and that there is accumulated change over generations, it is not possible to apply the term species properly to individuals. However, this inability to categorise, is often used to imply some biological occurance that one creature has some major difference compared to it's parent. As such, evolution does not need such an example to occur. X only gives birth to it's kind: For evolution to be true, we should be able to see dogs turn into cows, or fish into men This is the second interpretation. While this is a nice rhetorical argument it is a gain based on a complete misunderstanding of evolution. A key evidence for evolution and universal common descent, is the existance of a nested heirarchy, where life fits neatly into a tree structure when organised by common traits. The importance of this tree is mainly down to it not being violated; there are no examples where there are common traits in one branch that occur in multiple other branches without sharing a common ancestor with that trait. The reason for this, is that such traits and adaptations require the specific mutations (which occur by random chance), which are then selected for. Having the same trait in multiple branches would require such a trait to have evolved multiple times independantly which is massively unlikely. The same function can evolve as it has in terms of wings in bats and birds; but these traits are not the same. What this means, is dogs can't turn into any other species that is in existance. Each other species has a specific set of traits that cannot evolve twice. We can make dogs that are more cow like, in the same way dolphins are mammals that are more fish like than others; but it is not possible for those same traits to evolve twice due to probability. As such, expecting evolution to produce such a change misrepresents the theory. It pre-supposed that evolution MUST allow dogs to give birth to not dogs. This is not true. X only gives birth to it's kind: We should be able to see fundamental differences occuring between descendants and ancestors The final way the argument is presented (when interpreted liberally, and most scientifically), is that Evolution should be able to produce species with significant amounts of differences from an ancestor that amounts to some "fundamental" difference, or something that is now a different "Kind". The first issue with this, is that species cannot out-breed their ancestry. No matter how many generations and species that were produced from the first Eukaryote; they are still eukaryote. No matter how many generations and species spawned from the ancestor or verterbrates, they are still verterbrates. Humans are still classified as therapsidia; because we are still therapsids because the diagnostic features of those species are passed down and shared with all ancestors. In this way, no species will ever become fundamentally different from it's any of it's ancestors. A Dog will never produce a non-dog in the same way a mammal has never produced a non-mammal. This is evidenced in the nested heirarchy and the fossile record too; at no point did any species become different than it's ancestor: such an occurance would indeed invalidate evolution by producing a violation of the nested heirarchy. The second issue comes when you take the argument even more liberally and assume that a "fundamental difference" is merely a number of additional traits. This is where the argument becomes dishonest. Evolutionary biologists have seen innumerable different traits in multiple species evolve and accumulate. From dogs, to flies, to sticklebacks and many others. We have seen changes in organ structure, size, shape, bone formation, bone structure and a great number of other types of mutation that need to have occurred at some point to explain the biodiversity of life. In this regard, seeing species differ by 1 trait, or 2 traits is not enough; with the lack of a definition of what "Fundamental difference" actually means, there is no way to objectively define when one species starts to become different from another. It is "intuitive" that Fish and humans are fundamentally different as they have a lot of different traits. However, it is not quite as intuitive when you start getting to more closely related species. For example the most amphibian like fish compared to the most fish like amphibian. In this regard, this argument deliberately makes it unclear exactly how much change is "fundamental", or how much change is required to make a "new kind", meaning that whoever posts such a statement is free to reject any example of observed change as not meeting their criteria, as there is no definition of what that criteria actually is. [1] . http://en.wikipedia.org... [2] . http://www.talkorigins.org... [3] . https://www.princeton.edu... [4] . http://evolution.berkeley.edu...