Recently, I found myself in a discussion of the contributions of various scientists, and Darwin’s contribution to evolutionary thought. As is often the case when evolution is discussed, there was some dissent. Although the dissenter did not espouse creationist views, he kept saying that evolution was not fact, but dogma.
Sigh.
Since this was a civil discussion, I carefully explained about the process of evolution versus the fossil record. He persisted with evolution being dogma, not fact. He went as far as to say that since no one has witnessed “evolution” (by which he actually meant macroevolution), it was only speculation – one possible explanation. I drew upon lessons, analogies, comparisons, and everything else I could think of. I wouldn’t have, and perhaps shouldn’t have, but he seemed so otherwise reasonable. But he persisted. And so, I would like to make my case once and for all, so I can refer back to it as necessary…
Let me begin by defining the term “fact”. I will not attempt to reinvent the wheel, but will instead cite Wikipedia:
Generally, a fact is defined as something that is true, something that actually exists, or something having objective reality that can be verified according to an established standard of evaluation. There is a range of other uses, depending on the context. For example, fact may be argued under authority of a specific pedagogy, such as scientific facts or historical facts. Rhetorical assertion of fact is often forwarded without an implied or express basis of authority. (http://en.wikipedia.org/wiki/Fact)
From Merriam-Webster (http://www.merriam-webster.com/dictionary/fact):
1: a thing done: as a obsolete : feat b: crime <accessory after the fact> c archaic : action
2 archaic : performance , doing
3: the quality of being actual : actuality <a question of fact hinges on evidence>
4 a: something that has actual existence <space exploration is now a fact> b: an actual occurrence <prove the fact of damage>
5: a piece of information presented as having objective reality
And for the sake of argument, here is the definition of dogma:
Dogma is the established belief or doctrine held by a religion, ideology or any kind of organization, thought to be authoritative and not to be disputed, doubted or diverged from. (http://en.wikipedia.org/wiki/Dogma)
And from Merriam-Webster:
1 a: something held as an established opinion ; especially : a definite authoritative tenet b: a code of such tenets <pedagogical dogma> c: a point of view or tenet put forth as authoritative without adequate grounds
2: a doctrine or body of doctrines concerning faith or morals formally stated and authoritatively proclaimed by a church
(http://www.merriam-webster.com/dictionary/dogma)
From these four definitions, I can but conclude that by “dogma”, what was meant was “A piece of information put forward as established belief on the basis of authority, not to be disputed, but without proper substantiation”. This is just so wrong on so many levels.
First off, let me just say that despite the many individual scientists who may be sufficiently egotistical to argue a point based on authority, science, as a whole, would collapse if individual authority were the sole basis of our understanding of the world. If you can show, reproducibly, that a tenet of science is false, that tenet will fall. Period.
Now, on to the argument.
The statement that evolution is not “fact” because no one has witnessed it implies two things; first, that things not witnessed by humans can not be proven to be factual, and indirectly that things witnessed by humans can be taken to be factual. In other words, human perception is the arbiter of factualness. Factuality. Factishness. You know what I mean. This implies that since I have seen Criss Angel hover through the air without visible support, I am in a position to assert that the laws of physics are not absolute, and do not apply to this individual.
No? Why not? Is it because Newton was such an authority that we have to believe him? No, it is because gravity is a fact. We know its behaviour from experience, and from scientific observations from the very small to galaxy clusters. Our perceptions, therefore, can be fooled into seeing things that are not factual.
It is also possible to know that things are true – factual – without ever having been witnessed. If you come across a dry riverbed, for instance, you can say with certainty that a river once ran in that riverbed, since nothing else produces that kind of mark on the land – though you did not witness the river flowing. We can say with certainty that Meteor Crater was caused by a meteor, despite a lack of witnesses. And we can say that the core of the sun is fusing hydrogen – yet no one has been there. So to say that something cannot be factual because it has not been witnessed is plainly false. We can say that an event or phenomenon is factual if we see the dircet effect, or a clear record, of that event.
The technical definition of evolution is a change in allele frequency in a population – or, more simply, change over time. There is no implied directionality (ie that evolution always produces more complex life from less complex life). The same mechanisms that drive small changes (microevolution) also drive more significant changes (macroevolution), but I will save that for a later post. This post is to argue that change over time – and significant, macroevolutionary change – can be called factual without ever having been witnessed.
The first line of evidence for the fact of evolution is the fossil record. The age of exposed rock formations can be determined to within 1% or better through radioactive decay dating methods. These dating methods are not only self-consistent, but follow from our understanding of nuclear physics. By examining sedimentary strata of different ages on a worldwide scale, we get a snapshot of the differences in the flora and fauna in different times. In some locations we have millions of years worth of almost continuous deposition exposed, and we can see progressive change in the animals and plants fossilized in these layers. Although an individual snapshot does not in itself show change, a sequence of snapshots begins to provide a framework – in this case that flora and fauna are similar, but with distinct differences – in different strata separated by time. The greater the number of samples we find, the finer the resolution of our picture of what is happening. Just as a series of individual images, if taken close together, can produce moving images on a screen that accurately reflect what has happened, so too can a good sequence of fossils accurately reflect what has happened over time. And we have museum collections full of good fossil sequences.
The second line of evidence is homology. This, in simple terms, is the recognition that shared features indicate a common shared ancestor. Just as you and a sibling may look alike, having inherited similar features from your parents, so too can features such as skeletal structures, tetrapodal body plan, arrangement of crannial nerves etc. be said to be inherited from a common ancestor. You inherit skeletal and nervous structures from your parents, as they are encoded genetically. The fact that you share those inherited traits with chimps and bats and lizards implies strongly that you share a common ancestry with those animals. More recently, DNA sequences have added weight to the homology argument, as many genes are shared among even distantly related organisms. The real strength of these lines of evidence, however, is that they corroborate the sequence of snapshots in the fossil record, and in some cases fill in the gaps even more.
Thus, I argue, we have no witnesses to a macroevolutionary event, but a mountain of evidence. It is more than fair to say that evolution, change over time in living things, meets the criteria of “something having objective reality that can be verified according to an established standard of evaluation”. Evolution is a fact – it is an actual occurence that has objective reality.
Posted by Bipedal Tetrapod 
Bipedalia 