Recently, some of my corp mates were discussing science (and epistemology more generally, though I am unsure if they were aware of this) on corp comms. Since part of my degree has been to study the history and philosophy of science (and the history OF the philosophy of science), the arguments they were making reminded me of my first year, and the retrospective cringe at hearing naive beliefs I myself used to hold was so strong that I had to mute the conversation.
On one side, someone was arguing that evolution is just a theory.
On the other side, someone was arguing that evolution is true and proven.
I’ll start by saying both parties were somewhat right, and both parties were somewhat wrong. No one is at fault — public perception and understanding of science is shockingly bad, for both those who advocate and those who are skeptical of science. Hell, even a lot of scientists have a less than ideal grasp on their trade. However, this is not surprising; not everyone has three years to waste studying the history of modern science. Anyway, I will attempt to demystify the argument somewhat.
The party arguing for evolution being just a theory misunderstands the use of the word ‘theory’ in scientific discourse.
The party arguing for evolution being true and proven misunderstands the notion of scientific truth and proof.
The use of the word ‘theory’ is the easier one of the two to explain. The use of the word ‘theory’ in scientific discourse is not the same as the everyday use of the word. We might say something is a conspiracy theory, to indicate it is just a set of ideas and evidence for it is circumstantial at best, but a scientist would refer to the same thing as a hypothesis. For a hypothesis to attain the status of theory in scientific discourse, multiple papers must be published which describe successful, reproducible and falsifiable predictions made by the theory (usually around phenomena which had been previously unexplained). In other words, one cannot dismiss a scientific model on the grounds of it being ‘just a theory’; if it is indeed a scientific theory, there will be plenty of evidence for it.
A canonical example of such a prediction is gravitational lensing, which was predicted by Einstein’s general relativity, and was very counterintuitive at the time. The hypothesis predicted that the gravitational curvature of spacetime around massive objects would cause light to curve around them, which implied that distant objects in the sky near the edge of massive objects such as the Sun would appear to have moved because light coming from those objects would have been bent. This was famously confirmed by Arthur Eddington during a solar eclipse in 1919, and subsequent reproductions of this experiment have yielded concordant results.
Evolution specifically makes three important falsifiable predictions, all of which have famously been confirmed: (A) organisms will constantly mutate; (B) natural selection will favor successful mutations; and (C) there will be fossil records of extinct transitional organisms.
(A) is generally non-controversial. Various things like Down syndrome and some forms of myopia are the result of genetic mutations. (B) is also generally uncontroversial. Most mutations are not beneficial to the organism, often being fatal. The rare organism born with a beneficial mutation will thrive, outbreed and eventually outnumber the parent organism. This has been observed famously with the Peppered moth as well as other organisms.
(C) is the usual point of contest. The incompleteness of fossil records is often cited as a reason to reject the idea of evolution. Unfortunately for those who advocate this argument, it is completely irrelevant. It is often based on the misconception that evolution claims that organisms of one species evolve into another species — again, a misunderstanding of how a term is used in scientific discourse. The word ‘species’, in scientific discourse, refers to lines in the sand drawn on the long continuum of small, incremental changes between parents and their offspring. The ‘border’ between one species and another is arbitrary; determined retrospectively by biologists to systematically categorize various divergences in the continuum. In principle, if it was deemed necessary, three consecutive generations of an organism could be categorized as three different species; alternatively and more realistically, two different offspring from the same parent could be categorized as two different species.
For these reasons, evolution is considered a theory: an accepted, canonical, generally uncontroversial set of ideas in scientific disocurse. Not that there are no scientists that are skeptical of evolution — there are, but they are very much in the minority. This is a good thing — even the most accepted theories should undergo constant scrutiny so that anomalies can be identified and the theory can be improved or replaced by something with more predictive power.
Up to this point I have been apparently agreeing with the party who argued that evolution is true and proven.
Not so fast.
“Truth” and “proof”, in the context of science, are very dangerous concepts. There is a difference between science and something called scientism; these are often confused and the difference between them is rarely explored, perhaps because the practice of science is generally unnaffected by whether or not the scientist does or does not subscribe to scientism.
The difference is, ideologically, quite important. Science is a set of practices designed to improve the predictive power of theories through the rigorous application of empirical formalism. Scientism is the belief that science produces true knowledge about how the world is, often coupled with the claim that science is the only way we can discover truths about the world.
Scientism is a metaphysics; a faith, regardless of what its advocates claim. It does not produce predictions which can be tested with scientific rigor. Many scientists and philosophers of science reject scientism because of this, but many more do not (an interesting middle-ground was advocated by Willard V. O. Quine, who argued that though scientism is a myth, it is a pragmatic mistake to not subscribe to it).
The notions of “truth” and “proof” in science (not scientism) don’t require any notion of correspondence with some objective reality, but to agreement between a theory or body of theories and a prediction or observation. A claim is “true” in regard to some theory if it naturally arises out of that theory; for example, “no object can travel faster than the speed of light” is true of Einstein’s general theory of relativity, but not of classical Newtonian mechanics. Furthermore, a theory as a whole can be considered “true” to a body of theories when it is compatible with the other theories in that body and accepted by the majority of the practitioners of that program (see the Lakatosian notion of a scientific programme for more information), or to the scientific discourse as a whole when the theory is considered the most successful out of a group by scientific concensus (see Kuhn’s structure of scientific revolutions for more information).
Similarly, a hypothesis is “proven” when the prediction or predictions it makes are observed.
However, notice that this notion of “proof” does not in any way imply that a hypothesis, once proven and accepted as a theory, is a true and certain description of the world, but merely that it possesses predictive power to some novel, successful extent.
Certainty in general is considered unachievable in science because of something called the Problem of Induction.
The Problem of Induction was formalized by the English empiricist David Hume. It outlines a huge problem with inductive reasoning, which is central to the practice of science. An inductive hypothesis that claims, for instance, that the sun will rise tomorrow morning, is based on the sun having risen every morning beforehand. However, it’s most certainly not necessarily the case that the sun will rise tomorrow morning — it is conceivable that it could just go out or, more realistically, a cataclysm could happen to halt or significanly slow the rotation of the earth.
Hume himself made an analogy to a turkey being fed at a particular time in a particular place every day of the year, to the point where it begins to expect food at this time in this particular place every day. It begins to approach this place every day at this particular time. Come Christmas day, however, it is slaughtered and eaten; a violation of its evident inductive hypothesis that it would be fed at this particular place and time every day.
He also spoke about pulling colored balls out of a bag — if you pull 10 white balls out of the bag, you may form the hypothesis that all the balls in the bag are white, though it is perfectly possible that the next ball be a different color. Often this hypothetical exception to the inductive hypothesis is called a “black swan”, based on the idea that sseing many white swans would support a hypothesis that states that “all swans are white”, but seeing a single black swan will falsify that hypothesis (see Popper’s falsificationism for more info).
The problem Hume identifies is that inductive reasoning relies on the premise that the future will be similar to the past, which is something we simply cannot know, empirically test or simply cast away. It is also not trivial — we are often misled by this premise in our own inductive reasoning.
So, to return to the question of evolution.
Evolution is considered “true” and “proven” in the strict scientific sense; “true” in that it is consistent with and central to modern biology and accepted almost unanimously by scientists in that field; “proven” because when it was introduced, it made predictions which were counterintuitive, but were nevertheless observed.
However, there is no certainty as to it being a description of reality. Science doesn’t care whether or not it is; merely that it makes good predictions, and no “black swans” have been observed to suggest that it was ever any different (at least as far back as the origin of life, which is itself still a problem being researched in both biology and chemistry).
Those that do believe that is a description of some objective reality are making a rather unnecessary jump; whether or not reality can be properly described formally and certainly is still up for debate, and even whether or not this hypothetical theory of everything actually describes reality or simply perfectly predicts all emergent properties of it is unclear (notice the question of which to accept between one or the other is purely philosophical; neither makes any empirical prediction which can be used to distinguish them through science).
My position is that a healthy skepticism is in order. Don’t blindly trust the science because it is always changing, as it should be. However, don’t just ignore it (climate change IS happening, regardless of what some politicians who have their pockets lined with money from oil companies would like you to believe). It is not a provider of certainty, but it is the best we’ve got as far as predicting the future goes.
The Omnisphere 
