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Evolution is backed by scientific evidence

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In this debate, I seek to prove that the theory of evolution is indeed supported by numerous pieces of scientific evidence. Scientific evidence for evolution include transitional fossils, observed speciation (macroevolution), and beneficial microevolution. To succeed in proving that evolution is indeed supported by scientific evidence, I will have to first show that it is possible for evolution to change life to how it is today (speciation), and then show that evolution is responsible for life seen today. (transitional fossils) 

Point 1: Fossil Evidence

Evolution is supported by numerous fossils between reptiles and birds, reptiles and mammals, and primates to humans. This shows that evolution is indeed responsible for life as seen today.

The logic of my argument will be presented in this form:
Premise 1: If and only if evolution is true, then we should see transitional fossils.
Premise 2: We see a lot of transitional fossils.
Conclusion: Evolution is (likely) true.

Justification  for Premise 1: Evolution states that organisms can change over time.  Those organisms can be, sometimes, fossilized. If species X has the  ancestor species A and is the ancestor of species B, then X shares some  traits of both species and a fossilized X can be considered a  transitional fossil.

Justification for Premise 2: Transitional  fossils between reptiles and birds, reptiles and mammals, and primates  to humans have been found. [1] In fact, there are no known gaps between  dinosaurs and birds. [1] This falls in line with the predictions of  evolution. Also, if we assume evolution to be true, then every fossil is  a transitional fossil, between two or more species. However, the  transitional fossils do line up, even if we do not assume evolution to  be true.

The conclusion follows from premises 1 and 2.

Point 2: Observed Speciation (marcoevolution)

Definition of a species: "Related organisms capable of
 interbreeding and producing fertile offspring."

The logic goes like this:
P1: If and only if evolution is true, then we should see new species forming.
P2: We see new species forming.
C: Evolution is (likely) true.

Justification for P1: Evolution predicts that new species can form.

Justification for P2: Two examples of new species will be listed.

1. Goatsbeards
Goatsbeards  are wild flowers introduced from Europe to America. Three species were  initially introduced. They interbred, but could not produce fertile  offspring. (The hybrids were sterile), meaning that they were 3  different species. In the 1940's, two new species of goatsbeards  appeared, which produced fertile offspring only when breeding within  their species, and not with the species it evolved from.[2]

2.Drosophila paulistorum
Drosophila paulistorum,  a type of fruit fly, had a speciation event sometime between 1958 and  1963. Crosses with other strains only produced sterile hybrid flies,  meaning that the fruit fly are a new species.[2]

The Conclusion follows from the premises.

Point 3: Observed Microevolution

P1: If evolution is true, then microevolution should happen.
P2: Microevolution happens
C: Evolution is (likely) true.

Justification for Premise 2:

An  experiment, done by professor Lenski over 20 years, found that a  population of E.coli evolved the ability to metabolize citrate, despite  the fact that E.coli were normally unable to do so.[3] A later study  done in 2012 isolated the exact mutation that caused this, proving that  no contamination has occured. [4] This is, by definition,  microevolution, as no new species has been created.

Observed  Marco and Micro evolution, as well as fossils proving that evolution  has happened in the past, means that the case for evolution being  supported by scientific evidence is strong.


Return To Top | Posted:
2014-12-26 03:00:20
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Rephrase it, "That evolutionary theory is justified by scientific evidence"
I think this resolution is debatable though. As con, you would need to spin a play on priori.
Posted 2014-12-25 18:19:59
Well by definition any scientific theory is based on facts. Why debate a truism?
Posted 2014-12-24 23:08:39
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