Thinking Christian

Last week I posted an article in which I attempted to show that evidence against evolution can legitimately be evidence in favor of Intelligent Design. I ran into some serious opposition on that, and even though my interlocutors’ objections there were often mis-aimed, they did lead me to think through the matter more deeply. I got the argument wrong last time. I’m stating it here in a corrected form. I’ll borrow some of my wording from the previous version so that this article can stand alone, though I’m going to change terminology somewhat for clarity’s sake. This article divides naturally into three separate sections, so I am going to divide it into three posts published simultaneously. For those who followed the earlier discussion, there is some new material in this post, and I would draw your attention especially to the fifth through seventh paragraphs (counting this as number one). The second and third sections are quite different from what I posted previously.

The question is whether it is legitimate to regard evidence against evolution as evidence in favor of ID. Evolutionists often complain that positive arguments for ID are lacking, and that ID offers nothing but negative arguments against evolution. I’m going to refer to that as The Complaint. It is indeed true that ID makes part of its case (though certainly not all of it) on the basis of arguments against naturalistic evolution, so ID proponents must take The Complaint seriously. Is there something inherently wrong with ID arguing its case this way? Can a negative argument against evolution really be a positive argument for ID? Or is negative argumentation conceptually flawed from the start?

I’m going to begin with the simplest level of analysis and work upward from there to a fully realistic level. This argument becomes complex later on. I have placed a tree-diagram representing the whole of it at the end of the third post in this series. You may skip ahead and use it to guide you through if you like.

I begin by noting that at this time there are only two possible explanations for biological origins on the table: either some intelligence was guiding it, or there was no such intelligent guidance. If the first is true, then some form of Intelligent Design is the true explanation. If not, then the only explanation currently on offer is undirected random variation coupled with natural selection, which I will refer to here as Naturalistic Evolution, or NE.

At the end of the movie Expelled, Richard Dawkins speaks of the possibility that life on earth was designed, and opines that ID could explain earth’s life if the designers were some alien creatures. That raised some hearty chuckles from ID proponents, but in our laughter many of us missed what else he said: that those aliens, if they existed, must have come about by Darwinian processes. For Dawkins there is only one route up “Mount Improbable” (the term he used for life’s increasing complexity in his book The Blind Watchmaker). That one route is the gradualistic path of natural selection acting on random variations.

If he is in fact right about there being only one naturalistic route to biological complexity, then there are only two options open for consideration: Intelligent Design in some form (which of course is not an option Dawkins would consider), and NE. These are fully dichotomous: if one is true, the other is false, and vice-versa. Mainstream evolutionary scientists insist that NE is fact, and that we know it is fact. One helpful way to express their certainty is to express it in terms of probabilities: their view is that p(NE)=1 and p(ID)=0.

For this analysis I define evidence E for theory T as any information that, if true, increases the probability that T is true. I distinguish evidence from proof: it is that which adds to the probability of T, not that which proves T. Evidence is not unidimensional or unidirectional; there can be evidences for and against T, and each piece of evidence E must be considered in light of its own virtues and faults, in context of all other evidences for and against T. Further, there is a time factor factor involved. E is evidence for T if p(T) at T2 is greater after the introduction of E than at T1, before the introduction of E. This before/after relationship could be logical rather than chronological; whether E existed or was known at T1 is not as important as whether it was included in the probability analysis at T1.

There are many mainstream scientists who insist, as Michael Ruse has, that “Evolution is fact, FACT, FACT!” In other words, the matter has been settled, and regardless of any possible future evidence,  p(NE)=1. There is no possibility that ID is true: p(ID)=0. I can’t fathom how they can take that position. Evidence has to have some capability of influencing a theory, doesn’t it? Or is evolution true regardless of evidence? That’s hardly science.

Since “fact, FACT, FACT!” in that form is therefore fallacious reasoning and also bad science, I’ll proceed by entertaining the possibility that there is at least conceivably some evidence E that could reduce our confidence in evolution (even by the smallest fraction) such that  p(NE) < 1. That’s not assuming much. It’s a lot more reasonable than insisting that NE is true no matter what evidence might surface.

Now, if Dawkins is right that NE is the only possible naturalistic route up Mount Improbable, the probability equation for origins must include only the terms stated so far here; thus, p(NE) + p(ID)= 1. These are the only options on offer. If the probability of either term is 1, then the probability of the other is 0; if the probability of either term increases or decreases by some degree n, then the probability of the other term decreases or increases by n. 1 – p(NE) = p(ID), and 1 – p(ID) = p(NE).

ID theorists argue that certain features of the natural world are inconsistent with NE. The Cambrian Explosion is one of them. It is hard to explain on NE terms how it came about. This is an example of a negative argument against NE. This post is not about whether that argument is true or not; it is about whether, if there is merit to the argument, it counts legitimately as an argument in favor of ID.

And it seems to me that given a binary, dichotomous relationship between ID and NE, it must; for p(NE) + p(ID)= 1. Suppose for the sake of argument there is some merit to ID’s concerns about the Cambrian Explosion. The effect of that must be to reduce confidence in NE by some non-zero amount. Now suppose also that before this argument was presented, the universal consensus was that p(NE)=1. To the extent that the Cambrian Explosion argument has merit, confidence in NE must be reduced by some degree n, with the result that p(NE) = 1- n, and p(ID) = n. (The degree of change, n, depends on how successful the argument actually is.) Increased confidence in ID (its increase in probability) must be numerically identical to the decrease in confidence in NE, because the sum of the two probabilities must equal 1.

Therefore any evidence E that reduces the probability of NE as an explanation for origins increases the probability of ID as an explanation.

That brings us to the end of the first stage of this argument. To recap:

1. The Complaint is that ID’s negative argumentation against NE is somehow illegitimate, unscientific, or otherwise weak or wrong.
2. ID and NE are mutually exclusive.
3. On Richard Dawkins’ view, NE is nature’s only available method for developing biological complexity.
4. Therefore on that view, ID and NE fill the entire probability space for origins: p(NE) + p(ID)= 1.
5. And therefore any successful negative evidence against NE is successful positive evidence for ID:

That is the simplest view of the argument, and it seems pretty cut-and-dried if random variation coupled with natural selection (NE) is nature’s only option for building biological complexity, as Dawkins thinks.

But when I have written of this before, some have objected to my considering only two possibilities: ID (in some form) and NE. “How do we know these are the only two possibilities?” they ask. “Science marches on, and who knows what we might discover? Why do we assume that ID is the only alternative to NE? How could we know that?”

That question takes us to the second section of this article.

Tweet This Post

This is the second stage of an argument responding to what I have called The Complaint: that Intelligent Design’s (ID’s) negative argumentation against naturalistic evolution (NE; defined here as the development of life and its complexity through undirected random variation coupled with natural selection) is somehow illegitimate, unscientific, or otherwise weak or wrong. If you have not read the first stage, that would be the place to begin.In it I showed that in the simple case where we assume there are only two options on the table, negative evidence against NE is quite clearly positive evidence for ID. I expressed this in the probability equation 1 – p(NE) = p(ID), where p(NE) is the probability that NE is the true explanation of origins, and p(ID) is the probability that ID is the true explanation.

Now we must examine the possibility of more than two options. As I said last time, this argument becomes complex. I have placed a tree-diagram representing the whole of it at the end of the third post in this series. You may skip ahead and use it to guide you through if you like.

Recall that ID stands for origins being brought about by a designer. If there is a third option it cannot involve a designer, for that frame is already filled by ID; it must be another naturalistic explanation. At this point there is no naturalistic explanation on offer besides NE, so it must be an unknown naturalistic explanation. I will refer to it as the Unknown Naturalistic Theory, or UNT.

If we are to grant the entirely reasonable assumption that science could develop some other, new naturalistic explanation for the development of life and its complexity, then the probability equation we started with must be expanded:

p(NE) + p(ID) + p(UNT) = 1

We have no way of assessing UNT’s probability, but we can deal with that by considering two possibilities.

A.
p(NE) + p(UNT) = 1;
  p(ID) = 0

B.
p(NE) + p(ID) + p(UNT) = 1;  
0 < p(ID) < 1;
0 < p(UNT) < 1

I will deal with A in this post and save B for the next in this series.

A is a mathematical restatement of, “We won’t claim we’re absolutely certain that NE explains life’s origins; but we’re certain that whatever the explanation is, Design had nothing to do with it.” Often coupled with this statement is something to this effect: Science has made continuous progress in finding naturalistic explanations for natural phenomena. Attempts to use God (or some other Design process) to explain natural phenomena have consistently had to give way to naturalistic explanations. Therefore we think it’s reasonable to conclude that science will eventually demonstrate that the origin and complexity of life have fully natural explanations, whether NE or some other theory not yet conceived of.

The question there is, what evidence is adduced for this opinion? There is one kind of evidence that is offered, and another kind that is not even in the picture. What is offered is the history of science, and what is inferred from that is an extrapolation to the future of science. What is not even in the picture is evidence from nature. No matter what evidence E might surface in nature at any time in the future, E can only count as evidence for naturalism (NE or UNT), for p(ID) = 0, world without end, Amen. The probability of naturalism today, T1, is 1; the probability of naturalism tomorrow T2 will be 1, and the probability of naturalism at T3, T4, T5 … to infinity is 1. And this we are assured of, regardless of what evidence E might be introduced at some time Tn in the future.

That is either begging the question, simply stating ID is wrong and that’s that, regardless of what evidence should ever appear! or else, if it is not begging the question, it is placing enormous load on the evidence that has been offered on its behalf: the history of science. We must recall that science has not had uniformly increasing success in explaining what we observe in the world. It has gotten nowhere with explaining realities like consciousness, reasoning, purpose, meaning, free will, moral responsibility and even the origin of the first life. (Claims to the contrary abound, but as I — and many others — have argued elsewhere, they are philosophically uninformed.)

But even if that were not the case, extrapolation in a matter like this is hardly more than an expression of faith. To extrapolate without a supporting theory is bad statistics and bad science, and the only theory that could support this particular extrapolation is one that begs the question: the theory that all of life’s features will someday be explainable naturalistically.

So version A above is unsuccessful. To introduce p(UNT) into our probability equation that way is logically fallacious. We’ll have to pUNT (I’ve been saving up for that pUN) to version B and see whether it works. That will be the topic of the next post.

Tweet This Post

This is the third post in a series exploring The Complaint of evolutionists: that Intelligent Design’s (ID’s) negative argumentation against naturalistic evolution (NE; defined here as the development of life and its complexity through undirected random variation coupled with natural selection) is somehow illegitimate, unscientific, or otherwise weak or wrong. (This is not the place to begin if you have not read the first two posts; start here instead.)

So far I have shown that if NE and ID are the only explanations on the table for discussion, The Complaint is unjustified. I have also begun to address the possibility that NE and ID are not the only options; we have to consider that some currently unknown naturalistic theory (UNT) could surface someday as a third possibility. Using probability math, I have expressed two ways UNT could enter into consideration:

A.
p(NE) + p(UNT) = 1;
p(ID) = 0

B.
p(NE) + p(ID) + p(UNT) = 1;
0 < p(ID) < 1;
0 < p(UNT) < 1

And I showed in the last post that A is question begging.

But there is a non-question-begging way to introduce UNT into analysis, and that is B. It doesn’t assume ID is false and naturalism is true. So on first appearance it seems more hopeful, for those who would want to justify The Complaint. Could they be right, under B? Let’s take a look at this.

First, let’s recall that The Complaint has to do with how ID theorists use evidence against evolution in favor of ID. So let’s introduce our term E now. We’ll assume that at time T1 our confidence in NE was perfect: p(NE) = 1. But now we consider E, and find that it is evidence against NE, so that at time T2, our confidence in NE is reduced by n: p(NE) = 1 – n at time T2.

We can substitute 1 – n for p(NE) in our equation from B:

(1 – n) + p(ID) + p(UNT) = 1

Which is equivalent to

p(ID) + p(UNT) = n

Both terms on the left side of this equation are greater than 0 and less than 1. The question that The Complaint addresses is, can we rightly conclude that p(ID) varies directly with n? If p(ID) increases when n increases then negative evidence against evolution is positive evidence for Design.

It’s possible, mathematically, for p(ID) not to vary directly with n. It could happen in either of two ways:

Mathematically it’s possible that p(ID) is constant. In that case p(UNT) varies directly with n. Whatever evidence E appears that counts against NE, counts equally in favor of UNT. That’s really just a special case of what I argued in the previous post, however: no matter what evidence comes in at any future time, it cannot under any conditions count in favor of ID. All evidence is evidence for one naturalistic explanation or the other. For the deliverer of The Complaint to resort to that as support would plainly be question-begging.

It’s also mathematically possible that p(ID) varies inversely with n. That would require p(UNT) to vary directly with n, with some multiplicative factor such that when n increased, p(UNT) increased even faster. But that would be strange, to say the least, especially since UNT is by definition unknown. To assume that its probability varies with n that way is to assume that we know something quite unexpected and remarkable about the unknown. For The Complaint to rely on that would be nothing but special pleading.

But it’s worse than that, in reality, for in fact we do know something about UNT: it hasn’t been thought of yet. Richard Dawkins says it doesn’t even exist. So while we can’t eliminate the possibility of UNT completely, we can safely set its value near zero. And the closer p(UNT) is to zero, the more likely it is that p(ID) varies directly with n.

So how shall we assess The Complaint now? We have to allow that it is conceivably legitimate, but only if p(UNT) varies directly but multiplicatively with n. Only if we resort to special pleading, in other words. My conclusion is that negative evidence against evolution can legitimately be taken as positive evidence for ID.

This has been an extended argument with multiple branches. I have attempted in my ham-handed way to illustrate it through the following diagram, which may be useful as a guide to you in re-reading and re-evaluating these three posts. Or (since my space was limited, and so is my experience with these things) it may not be that helpful.

Tweet This Post