A couple of weeks ago a very good post on abduction appeared on Mormon Organon (view it here). In that post, Mr. Peck correctly argues that abduction, or inference to the best explanation as it is sometimes called, refers to a sort of logical competition between theories. A theory that explains a body of evidence better than its rival theory is more reasonable to accept. If we apply this concept to theories on the origins and complexities of species, evolution is the clear winner, although probably more by default than anything else. But this explains why evolution is so widely accepted. It is simply the best scientific theory available for explaining the origins and complexities of life.

Mr. Peck also effectively pointed out that most theories are created through accumulating observation and empirical facts. The process of collecting empirical facts and creating a suitable theory that explains those facts is sometimes referred to as an inductive generalization. Put differently, an inductive generalization involves moving from many observations to a single, explanatory theory. Many great theories like evolution have been created via inductive generalizations. Creating scientific theories through inductive generalizations is not a theoretical faux pas or scientific weakness; it is just one aspect of how science progresses.  

So far we have only considered the logic of theory discovery. As stated above, scientific abduction plays a role in determining which theories gain prominence. It also plays a role in determining which theory will be singled out for confirmatory investigation, however, the process of confirming a theory through testing is different from abduction.

The most common approach to confirming scientific theories is the hypothetico-deductive (H-D) model of science. In short, the H-D model of science involves deducing observational hypotheses from a theory and testing those hypotheses in a controlled setting. If the results are consistent with the theory’s expectations, then the theory is tentatively confirmed. If the results are not consistent with the theory’s expectations, then the theory is tentatively disconfirmed.

Not all H-D tests of hypotheses are created equal. Influential philosopher of science Karl Popper pointed out that an ideal test of a hypothesis is one that is falsifiable and addresses, as much as possible, the core tenets of the theory. Popper called it making a risky prediction.

Theories that repeatedly survive falsifiable tests and risky predictions gain “certainty” status; we become so certain of their truthfulness that we start calling them laws instead of theories. Theories that have repeatedly survived falsifiable, risky predictions include Relativity, gravity, and the Germ Theory of Disease, to name a few.

Now, because of lengthy time requirements needed for testing falsifiable macroevolutionary hypotheses that make risky predictions a’la the H-D model of science, macroevolution has not risen to the same level of certainty we typically associate with Relativity and gravity. Relativity and gravity have repeatedly undergone crucial testing. In most cases, the results of these tests have been confirmatory (i.e., 1919 Sir Arthur Eddington solar eclipse expedition, atomic clocks in airplanes, and every time you drop your pen it falls, as predicted.)

I don’t have a problem with people saying that they personally accept the certainty of the theory of common descent. Evolution’s pre-eminence in the game of scientific abduction makes this statement legitimate. I do have a problem with people claiming that macroevolution and common descent have been proven beyond a reasonable doubt. IMO, the scarcity of confirmed falsifiable and crucial tests of macroevolutionary processes does not warrant such claims.

Sources: (Philosophy of Science: A to Z by Stathis Psillos; Philosophy of Science: The Central Issues by Curd & Cover; Philosophy of Science: A Short Introduction by Samir Okasha.)

Post #2 on Intelligent Design (ID) (see below) argues that ID is scientific, as long as it focuses on natural processes and approaches these in an empirical and rational fashion. But perhaps the more important question is: “Is ID science rigorous?” Let’s take a look at how well ID satisfies commonly accepted criteria of scientific rigor.

Testable Predictions – A good theory allows us to frame testable hypotheses.  Does ID allow us to make predictions about what is going to happen or what has happened in the past, and are we able to investigate these phenomena in an empirical manner? 

Sure. The theory of ID can produce hypotheses that may be tested in an empirical manner.  For instance, a common ID hypothesis is that there are systems that are irreducibly complex. (Irreducible complexity is the idea that some living mechanisms are too complex to have arisen through the gradual process of natural selection because each part must be in place for the structure to function.) We can test this hypothesis by looking for irreducibly complex systems in nature.  In time more complex hypotheses such as “biological systems smaller than size X designed to carry out functions of sophistication Y are irreducibly complex” may be possible.

However, to the best of my knowledge irreducible complexity (IC) is currently limited to “let’s go out and find evidence for IC.” What is lacking is some sort of manipulation of the IC process in the laboratory that would allow conclusions like: We manipulated biological system X in our laboratory and, true to our prediction, the system evolved irreducibly complex mechanism Y because of our manipulation.  In my opinion, this limitation puts IC on the same level as macroevolution – there is plenty of evidence in the real world supporting both hypotheses, but currently neither is capable of being subjected to crucial tests in a controlled laboratory setting. Two limiting factors are (a) in the case of macroevolution, a very long time is required for new life forms to supposedly evolve, and (b) in the case of IC, we know very little about the intelligent design language and whether or not we can influence it.  

Presently evolution has the upper hand on testability and predictability because we are able to manipulate genomic and environmental events in a way that allows us to test and predict microevolutionary events. If ID is to become a viable competitor, it will need to generate the same level of testability. According to influential historian of science Thomas Kuhn, new, competing scientific theories gain credibility when they offer fruitful alternatives to explaining existing phenomena and predicting new phenomena.  Anyway, ID is a relatively new science; we’ll see what happens in the next few decades. 

Falsifiability – A good theory is falsifiable. Does ID allow for risky predictions that will allow us to prove that it is false?

Sure. In fact, opponents of ID are hard at work falsifying the irreducible complexity (IC) hypothesis. This is a good thing because it means that a major hypothesis of ID is falsifiable. So has IC been falsified? Scholars like Ken Miller say yes. He claims that the creation of the bacterial flagellum (a complex, multi-part propeller system) can be explained by natural selection and is thus not irreducibly complex. He has pointed out that if we remove 40 of the 50 separate parts in a bacterial flagellum and left the 10 protein parts connected to the membrane of the cell, those remaining 10 parts may function as a Type-III secretory system. So this discovery refutes IC, right? 

In a strict Popperian sense, the answer is yes, but Popper’s theory of scientific progress is too idealistic - the correct answer is no. Science does not progress according to the strict falsificationist doctrine, and for good reasons which I will not go into here, but here are three important points to consider.  

First, scientific hypotheses are rarely in final form straight-out-of-the box, so to speak. At the first sign of contrary evidence, proponents don’t outright reject their hypothesis, much to the chagrin of their opponents. Advocates of a hypothesis usually modify the hypothesis to save it from rejection (called ad hoc explanations). As the evidence against a hypothesis builds and the hypothesis becomes overly complex due to constant modifications, then the possibility of outright rejection by the scientific community becomes a reality. Some say evidence against IC is mounting, so we will have to see what happens. 

Second, a crucial test of the secretory system is needed to provide more definitive evidence, yet no such test has been done.  Such as test might include taking the 10 genes that produce the part of the bacterial flagellum that connects to the cell membrane and replacing them with the corresponding 10 genes in the secretory system to see if a working flagellum results, and vice versa. This sort of test would establish whether or not the two mechanisms are truly similar.  

Third, by themselves, individual disconfirming tests rarely provide sufficient evidence to disprove a theory. Theories rely on several hypotheses and rejecting one hypothesis does not bring the whole theory crashing down. If research on the secretory mechanism ends up disproving IC, will this disprove ID? Well, it usually takes several disproved hypotheses to disprove a larger theory so the answer is ‘no’, that is, unless the theory rests on ONE major hypothesis. In this case, IDers would be wise to not place all their eggs into the irreducible complexity basket. If this is the case and IC falls, then ID will fall too.

Tentative Stance – scientists must recognize that their theories may one day be proven false. Are proponents of ID willing to accept that their theory may one day be proven false?

The idea that ID may be proven false is a HUGE problem here, folks. What sincere believer would be willing to consider that there is no God, or be willing to accept that there is no evidence of divine design in nature when the scriptures say otherwise? Here we see the real danger of tying up theology with science. If you bet your religious beliefs on a scientific idea being true, what happens when that scientific idea is eventually proven false, as so often happens? You could go into a faith crisis tail spin. 

I believe that ID proponents will hang onto their theory in a dogmatic fashion if disconfirmatory evidence builds. They will do this because of their religious convictions in God, but it is not very scientific to hold onto a theory that has been disproven. In the past, those who have held onto dead theories are often viewed as nonconformists who are unwilling to accept scientific progress. Thomas Kuhn says that these people often go to their graves holding onto dead theories. 

I have been fairly hard on ID with this last point, but I believe that it is risky to tie-up religious beliefs with science. I consider my religious beliefs infallible and my scientific beliefs to be fallible. Yes, I am more confident in the reality of my faith-based experiences than I am in the reality of scientific theories about the natural world.  

Now, to level the playing field on this issue, it is fair to say that evolutionists are equally dogmatic about evolution. This claim is evidenced by the way the evolutionary community has attacked ID from the get-go. I am not talking about the legitimate concerns with religious creationism; I am talking about the “you are crazy and unscientific to challenge evolution” attitude. This dogmatic attitude, which was effectively portrayed in Ben Stein’s film Expelled, is unscholarly. 

Concluding Thoughts 
ID can be scientific.  It is anti-scientific to deny a legitimate endeavor like ID a voice in the scientific marketplace of ideas. If ID has legitimate ideas to bring to the table, then let’s hear them out and then allow debate, refutation, and criticism. ID will live or die; either way, let the scientific process, not the political process, decide its fate. 

ID should not be rejected outright just because it presents a theory that challenges evolution. One of the virtues of science is that it is a democratic institution in the sense of encouraging an open and free exchange of ideas. It should never prematurely foreclose on legitimate ways of viewing the natural world. This, I believe, is the main message of Expelled.