Evolution is the only viable explanation for the origin of all the species that exist today.

I must point out, though, that my opponent assumes that evolution applies to the fauna of the Earth alone. This is not the case. Plants (believe it or not) are living beings, and can reproduce, and can mutate. Therefore, plants are prone to evolution as well. For this debate, I will be dividing my argument into two main sections. The first section will be entirely devoted to discrediting the validity of creationist theory. The second will be for defending the validity of evolutionary theory, and therefore rebutting the Con's argument. PROS CASEI. Evidence against the creationist case. The strongest evidence against the creationism case, is actually the lack of evidence. If Creationism was a scientifically valid theory, then there would be evidence indicative of creation. There is, however, no such (legitimate) evidence. A) Argument From Design? The first argument that is used to support creationist theory is that the universe is complex, and therefore must have a complex designer. This, however, is a non-sequiter. No complex creation comes from a single-sole designer, rather, the accumulated knowledge of all beings that had previously contributed to the creation of any complex thing. Such is the case in evolution. A species of bacteria consumes only resource X. Randomly, A mutation occurs that allows the bacteria to also consume resource Y (as well as X). Because the mutated generation of bacteria is better suited for survival, it is able to reproduce more effectively, thus spreading the genetic code required for the consumption of both X and Y. Suppose though, that the bacteria had instead randomly mutated a generation of cells that could only consume resource Z, which was sparse. That strain of bacteria would eventually die off (or at least, would not be as successful in reproducing as the other strain). Over time, the bacteria become more and more complex, becoming better suited over time for survival. This is the process we call evolution. Every layer of complexity adds variety. This does not mean that it cannot create diversity as well. Suppose one strain of bacteria mutates to consume X and Z. Though possibly not as successful as the strain that consumed X and Y, the strain that consumed X and Z would still likely thrive. Repeat this process over millions upon trillions of years, and then you have all life that exists on the earth today. B) Argument From Cause? Many creationists may argue that the universe began to exist, and therefore has a cause, and this indicates the existence of a divine creator deity. This is not the case. First of all, there is no evidence to prove that the Universe ever "began. " This may be too abstract for my opponent to comprehend, but the is no way to empirically prove that the universe has a "beginning" in time. Even if the was a cause to the universe, this does not in any way prove that that same "cause" also created complex life on Earth. C) Occams RazorOf course, at the end of any scientific question (Why does mass have gravity? Why are the laws of physics the way they are? ) you can simply add "because god made it so" but this is simply an extra assumption to add your hypothesis, or theory, and is therefore to be rejected, under Occam's Razor. ConclusionThere is absolutely 0 legitimate evidence demonstrating that life was magically wished onto the Earth by an imaginary spaghetti monster. There is, however, an abundance of evidence indicating that life began on the earth very simply, and (through random mutation, natural selection, and the other various forces of evolution) became more and more complex over time. II. Rebutting Con's Case/The Scientific Validity of Evolutionary TheoryA) RebuttalFirst my opponent takes shot's at Darwin's original theory. This is not a valid attack on modern evolutionary theory, however, because that is not the nature of scientific theory. The primary difference between creationism and evolution regarding scientific validity is this. Evolution takes facts, and from that draws conclusions (aka Theories). Creationism takes a conclusion, and then tries to fill in the blanks with facts. The beauty of a scientific theory is that if there is a flaw, the theory is then revised. When the atom was discovered, we believed that the atom was like a big ball of plum pudding, this was mostly true, but not entirely. When we discovered that fact (atoms are mostly empty space), we revised the theory, to better increase our understanding of atomic structure. Such is the nature of all scientific theories (including gravitational theory). Creationism isn't scientifically valid because it is a zero-sum answer. There are no further questions. Which is unscientific. Even in the case of gravity there is still the question of WHY does mass have gravity? In the case of creationism, there is no question, only an answer based on zero evidence. The following paragraph is wholly untrue. My opponent seems to believe that in the natural world "beauty" is just a magical abstract concept with no rhyme or reason. In reality, the reason that you might find a certain person "attractive" is because your brain believes that if you were to mate with them, they would likely provide you with a healthy offspring. This is true in all of the animal and plant kingdoms. Furthermore, evolution occurs when mutant generations with unfavorable traits die before reproducing, and mutant generations with favorable traits reproduce often. Next my opponent claims that all life ceased to exist when the dinosaurs died. This is not true. During the mass extinction of dinosaurs, not even all dinosaurs went extinct. . http://en.wikipedia.org...;B) Fossil Records, and Radio-Carbon DatingThe best evidence that we have of macro evolution is the extensive fossil records of the evolutionary process. The most interesting of which (of course) being our own. the evolutionary steps of the Human Race. . http://en.wikipedia.org...It was over vast spans of time that we, Homo Sapiens, evolved from simple ape-like creatures. Over time, natural selection favored our intelligence, our communication skills, and eventually our tool manipulation. This is what allowed our species to thrive, and eventually develop complex sentience. C) Micro-evolution+Time=Macro evolutionMy opponent may make the argument that Humans and apes are not distinct enough to the point to where a line can be drawn between which ape is more or less "ape. " Over time though, micro-evolution, is macro evolution. My opponent cited a lovely source that explains the process by which animals evolved to walk on land. He says that 72% of the earth is water (not true 72% of the surface is covered by water, 99% of the earth is rock/dirt/solid), why move out onto land? I'll explain why the ability to survive on dry land was a favorable trait in natural selection (keep in mind this process requires an unfathomable amount of time). Animals did not evolve to survive on land first. Plants did. Plants originally lived only in the ocean, but photosynthesis is obviously more favorable on land. Plants that lived in areas prone to tidal shifts eventually developed stiff cell walls that allowed the plant to remain upright on land, therefore maximizing the plants survivability, increasing the reproduction success rate, etc. Then, when plants were thriving on the land, Fauna began to develop the ability to live on land, in order to gain access to the resources on land. My opponent essentially argues "the water is good enough, why go out on to land? " Which is the same to say, "Steak is good enough for dinner, why ask for desert? " because you thrive more when your species can also access the resources found only on land.