When Absence of Evidence is Evidence of Absence

There is a popular and catchy saying which I myself have been caught repeating in the past, but which, for all its intuitive appeal, is false; namely, that the absence of evidence isn’t evidence of absence. Many a new-atheist has repeated the mantra that there is no evidence for God’s existence, insinuating thereby that this absence of evidence is good evidence for atheism. William Lane Craig, a noted philosopher, theologian and tireless Christian apologist has responded as follows:

[Atheists] insist that it is precisely the absence of evidence for theism that justifies their claim that God does not exist. The problem with such a position is captured neatly by the aphorism, beloved of forensic scientists, that “absence of evidence is not evidence of absence.” The absence of evidence is evidence of absence only in cases in which, were the postulated entity to exist, we should expect to have more evidence of its existence than we do.1

He has reiterated as much more informally (but more elaborately) on his podcast, ReasonableFaith, where he says:

The absence of evidence will count as evidence of absence when if the thing existed, then having surveyed the grounds, so to speak, we would expect to see evidence of their existence, and we don’t see it. And so, for example, in the case of fairies, if they existed then we ought to be able to find traces of their existence – their dead bodies when they die, their carcasses, other sorts of remains, little clothing factories where they build their clothes, and we ought to detect them flying about just as we detect dragon flies and bumblebees – but we don’t. So this would be a case where I think the absence of evidence would count as evidence of absence.”2

On this view, the absence of evidence only counts as evidence of absence when we have some reason to expect to see the evidence ex hypothesi. This has enormous intuitive appeal; consider the hypothesis that there is at least one tiger in India. Can the fact that I, sitting in Canada, currently see no tiger really count as evidence that there is not at least one tiger in India? Surely not; presumably because that evidence isn’t expected on the assumption of the relevant hypothesis’ truth. Elliott Sober, reflecting on absence of evidence, notes that in the case of arguments from absence “it is easy to see how each can be turned into a valid argument by adding a premise. The arguments have the form:

I do not have any evidence that p is true.
p is false.

Just add the premise

(P1) If p were true, then I’d have evidence that p is true.”3

This further highlights the fact that it is natural for us to think that absence of evidence is evidence of absence only when we expect the evidence ex hypothesi.

For years I found this response intellectually satisfying, but in recent years I have come to think that it is woefully mistaken. It is true that my failure to observe a tiger in Canada provides no evidence against there being at least one tiger in India, but it is not because I wouldn’t have anticipated seeing a tiger in Canada given that there is at least one tiger in India. All my affection and respect for Craig notwithstanding, if Craig means that absence of evidence E for hypothesis H is only evidence of absence (i.e., not-H) when the probability of E on H is greater than 0.5, then he is, I think, incorrect. In what follows I will try to explain why, as well as explore what to me seem interesting corollaries of Bayesianism.4

John Hawthorne, speaking about probability theory and the fine-tuning argument at a conference back in 2015, warned:

“Human beings, even intelligent human beings, are terrible at reasoning about probabilities. There’s enormous empirical evidence that human beings are terrible at reasoning about probabilities, and so we have to proceed with care.”5

Playfully picking on (presumably) a student in the audience, Hawthorne says: “Justin gave us the kind of awesome sounding principle… [that] if you don’t see something then that can be evidence of its absence only if you expect that you would get evidence were the thing there.”6 Not the cleanest off the cuff articulation, but clearly Hawthorne had in mind the principle for which W.L. Craig advocates. He continues; “that’s wrong… and I can prove to you that it’s wrong.”7 He proceeds to give an illustration using a hypothetical creature he calls a Dynx, where he stipulates that 75% of Dynx are invisible to the naked eye, and the probability that there is a Dynx in a box placed before us is 50%. We open the box, and we see no Dynx. The probability that there is no Dynx given our background knowledge and this new piece of information (namely that we do not see any Dynx) is approximately 57%. You can satisfy this for yourself by simply dividing up the space of possibilities (i.e., ‘seeing a Dynx in the box,’ ‘not seeing the Dynx in the box,’ and ‘there being no Dynx in the box’), eliminating the possibility of ‘seeing a Dynx in the box,’ and then expressing your updated probability assessment accordingly. So, even though we ought not to expect to see a Dynx in the box if there is one in the box, our failure to observe one is still evidence for their being no Dynx. This simple illustration (and others like it) seems to be entirely compelling. What, then, is the genuinely Bayesian determination of evidence?

On the Bayesian theory of confirmation,8 some evidence E will count as evidence for some hypothesis H (given background knowledge B) just in case E (conjoined with B) raises the (prior) conditional probability of H. To put it more formally, E will count as evidence for H just in case: P(H|E&B)>P(H|B). However, [P(H|E&B)>P(H|B)]⊃[P(~H|~E&B)>P(~H|B)]. In other words, if E provides any evidence for H, then ~E provides some evidence against H. It needn’t, of course, be the case that E provides as much evidence for H as ~E does for ~H, but it strictly follows from Bayesianism itself that ~E would be evidence against H just in case E would be evidence for H.

To illustrate with an example, let us take a hypothesis H1: “that aliens exist,” and evidence E1: “I am being abducted by aliens.” Obviously P(H1|E1&B)>>P(H1|B). What is not so obvious is that P(H1|~E1&B)<P(H1|B). The reason it isn’t so obvious is that ~E1 provides negligible evidence for ~H1 (even though E1 would provide compelling evidence of H1). If aliens abduct me, that’s really good evidence that they exist. If aliens do not abduct me that’s really poor evidence that they don’t exist. It may be some evidence, but it isn’t very much evidence.

Not only can the absence of evidence be negligible evidence of absence while the presence of that evidence would be altogether compelling, but the absence of evidence can even be inscrutable evidence of absence while the presence of evidence is scrutable and enormously supportive of the hypothesis in question. Take the example of a miracle, and for simplicity let us use the miracle of the bodily resurrection of Jesus of Nazareth. The bodily resurrection of Jesus, if it did occur, would be relatively good evidence for God’s existence; P(G|R&B)>>P(G|B). However, if Jesus had not been raised from the dead, would that provide any evidence against God’s existence? According to Bayesianism it would, but it seems like it would be not only negligible evidence, but even inscrutable evidence. There is no way one could put a figure (with any justification) on how much more confident it should make us in atheism that some miracle, like Jesus’ resurrection, did not occur. If we could give any estimate of what the probability is that God would perform a miracle when called upon to do so, for instance, then we could make some predictions about how many hospitalized people with terminal diseases (according to medical diagnosis) under observation get better when prayed for. We can’t make these predictions not because there is no actual probability of God doing a miracle, but because we aren’t at an epistemic vantage point from which we can assess that probability with any level of confidence at all.

Further, the evidence may not be merely negligible, but can in special instances be literally infinitesimal (an infinitesimal is a non-zero infinitely small quantity). Consider Hempel’s paradox9 for a moment; any observation of a pink shoe provides some evidence for the hypothesis that all ravens are black. The hypothesis that all ravens are black is logically equivalent to the statement that all non-black things are non-ravens. It follows, therefore, that any observation of a black raven is evidence that all non-black things are non-ravens, and any observation of a non-black non-raven is evidence that all ravens are black. An observation can’t be evidence for one without being evidence for the other precisely because they are logically equivalent statements, at least interpreted at face value; this is just what Hempel called “the equivalence condition.”10 However, it seems as though there are potentially infinitely many things which are non-black non-ravens which, at any moment, we will fail to observe. If this is so, then each of these instances of absence of evidence will count as instances of infinitesimal evidence of absence (or, at least, infinitely many of these instances will count as instances of infinitesimal evidence of absence). One thinks of the infinitely many miracles God could have performed at any given moment (e.g., growing a lost limb, bringing a dead child back to life, parting the Atlantic ocean); is it really the case that every instance of a miracle not happening provides some evidence against God’s existence? If so, and if there are infinitely many opportunities for God to perform a miracle of some kind (in infinitely many of which God decides to perform no miracle), does that not entail that the probability of theism is literally infinitesimal, or else that each instance (or, at least, infinitely many instances) of a non-miracle provides at most infinitesimal evidence against theism? This gets a little tricky, of course, because Bayesian theory isn’t really equipped to deal with cases of what we might call ‘transfinite probabilities,’11 but if we take its implications seriously even in such cases we will plausibly think that at least some things provide literally infinitesimal evidence for a conclusion or hypothesis.

An interesting objection to this suggests that there is not, even potentially, an infinite number of unobserved observables. Given the limited bandwidth of the human body as a kind of measuring apparatus,12 there may be infinitely many different but observationally indistinguishable events. Imagine, for instance, two pairs of pink shoes whose colours or sizes differ by so little as to make it impossible for any human being to tell the difference between them. For any of the attributes assessed by the five senses, there will be limited empirical bandwidth given the human body as a tool of observation. What this seems to entail is that there is not a potentially infinite number of different possible observations, in which case we needn’t concede the absurdity of infinitesimal probabilities. This objection is appreciably practical, but I’m not entirely confident that it settles the matter. After all, I can imagine a human being with “electron-microscope eyes”13 or with any number of other physical alterations which would allow them to observe an apparently potentially infinite number of different events. For any such alteration, I can imagine God miraculously bringing it about that observer S has precisely the alterations necessary to observe some miracle M1 which would have previously been indistinguishable from miracle M2, but is not now indistinguishable from M2 for S. Moreover, I’m not convinced that observational indistinguishability is terribly relevant; there are infinitely many possible pink shoes which I could now be observing, but am not, and even if infinitely many of them would be indistinguishable to me, failing to observe any one provides some evidence against the hypothesis that all ravens are black. So it seems to me that we’re stuck with conceding that at least some things provide literally infinitesimal evidence.

In summary, I think we have seen why the absence of evidence is evidence of absence in all cases except those in which the presence of so-called evidence would do nothing to raise the conditional probability of the hypothesis in question. Thus, my failing to observe a tiger in Canada provides no evidence against the hypothesis that there is at least one tiger in India not because I wouldn’t expect that evidence if there were at least one tiger in India, but because even if I were observing a tiger in Canada it would provide no evidence that there is at least one tiger in India.14 We have also seen that even when absence of evidence is negligible evidence of absence, or inscrutable evidence of absence, or infinitesimal evidence of absence (or any combination of those three), it will still provide some evidence of absence; if E would have been evidence for H, then the absence of E provides evidence against H.

Post Scriptum: I want to thank Tim Blais, Cale Nearing and Sean Boivin who provided me, in discussions subsequent to the original article, with food for thought without which I would never have made the improvements I have lately introduced above.

1 William Lane Craig, “Theistic Critiques of Atheism” The Cambridge Companion to Atheism. Edited by Michael Martin (Cambridge University Press, 2006): 70.

3 Elliott Sober, “Absence of Evidence and Evidence of Absence: Evidential Transitivity in Connection with Fossils, Fishing, Fine-Tuning, and Firing Squads,” in Philosophical Studies 143, no. 1 (2009): 64.

4 As a cautionary caveat lector; though I’m pretty confident that what I’m about to say is correct, I have not taken any class on probability theory (yet); if anyone thinks there’s some subtle mistake somewhere, they are encouraged to share it. I am more than open to updating my views.

8 Elliott Sober, “Absence of Evidence and Evidence of Absence: Evidential Transitivity in Connection with Fossils, Fishing, Fine-Tuning, and Firing Squads,” in Philosophical Studies 143, no. 1 (2009): 66.

9 James Fetzer, “Carl Hempel,” in The Stanford Encyclopedia of Philosophy, edited by Edward N. Zalta, (Spring 2017 Edition), accessed April 2, 2017. https://plato.stanford.edu/archives/spr2017/entries/hempel/

10 James Fetzer, “Carl Hempel,” in The Stanford Encyclopedia of Philosophy, edited by Edward N. Zalta, (Spring 2017 Edition), accessed April 2, 2017. https://plato.stanford.edu/archives/spr2017/entries/hempel/

11 If one dislikes this term because they think that probabilities can be no higher than 1, which makes them finite, I would suggest they think about how the conditions I just stipulated could imply that some hypothesis H is infinitely likely without having probability 1. However, if that doesn’t mollify the critic, I could agree to change the term to ‘non-finite’ probabilities.

12 I borrow here from Bas C. van Fraassen, who notes insightfully that “the human organism is, from the point of view of physics, a certain kind of measuring apparatus.” See: Bas C. van Fraassen, The Scientific Image, (Oxford: Clarendon Press, 1980), 17. 

13 Bas C. van Fraassen, The Scientific Image, (Oxford: Clarendon Press, 1980), 17.

14 If one thinks that observing a tiger somewhere raises the conditional probability that one may be observed anywhere then one will reject this conclusion, but they needn’t, in so doing, reject the principle this example is being employed to illustrate.

Advertisements

Theism, Evolution and Randonmess

A good friend of mine with experience lecturing neophyte philosophy students as a Teacher’s Assistant (at the university of Western Ontario) has reported to me that many, if not most, of his students believed that the theory of evolution and the existence of God each entail each other’s negations. This is a depressing report, especially to a theistic evolutionist such as myself. Since the compatibility of both the theory of evolution and the existence of God is so conspicuously obvious to me, it continues to baffle me that anyone should think them contradictory. Perhaps one of the reasons for this naïve assessment is that evolution’s being ‘random,’ is thought (rather unreflectively) to be incompatible with the notion that it has been divinely guided. Ignoring the fact that God’s existence doesn’t, on its own, logically entail his divine involvement in the world, there still doesn’t seem, on the face of it, to be any incompatibility between God’s existence (and divine involvement in the world) and the biological theory of evolution. However, perhaps these people are reasoning in the following way:

  1. If God exists & evolution is true, then God (must have) guided evolution.
  2. If evolution is true, then it was ‘random’ (which is stipulated as part of the theory itself).
  3. If evolution was random, then it could not have been guided.
  4. Evolution is true.
  5. Therefore, God does not exist.

Or
4.* God exists.
5.* Therefore, Evolution is not true.

Where is the problem with this reasoning? I think the problem is clearly with premise 3, though my critique is going to focus on sharpening, through analysis, the (so far) vague concept of randomness which makes its first appearance in the second premise. Here the work of Dr. Craig is useful; he has argued that what all biologists mean by saying that mutations occur ‘randomly’ is that they occur without a view to the benefit of the organism. Craig takes his cue from a prominent biologist, Francisco Ayala, according to whom:

“The meaning of “random” that is most significant for understanding the evolutionary process is… that mutations are unoriented with respect to adaptation; they occur independently of whether or not they are beneficial or harmful to the organisms.”[1]

Elliott Sober reiterated the same point when he explained:

“Let me talk about this idea of ‘guided’ mutations. This has been a kind of lightning-rod term. Creationists and Theists in the United States often hear biologists say that mutations are ‘unguided,’ ‘random,’ and they think that biologists are denying that God has any role in the natural process, and they think ‘well, if your theory says that [then] I reject it because I think that God is involved in everything that happens…’ what I want to describe now is what Biologists actually mean by ‘mutations being unguided.’ What I just described [above] is, I think, a misunderstanding of the biology. The idea that mutations are unguided says nothing about whether God plays a role in nature one way or another. So let me explain what biologists mean, or ought to mean, by ‘unguided mutations.’ When they say that mutations are unguided they do not mean that they have no causes; we all know that mutations have causes. Radiation causes mutations, smoking causes mutations, there are plenty of causes [of mutations] so [that] when you say they’re unguided or random it doesn’t mean that they are uncaused. What it means is that mutations have their causes, but they do not happen because they would be good for the organism in which they occur. Most mutations are deleterious, and the good ones that occasionally come along, the adaptive ones that fuel the evolutionary process, they have their causes too but they do not occur because they would help organisms to survive in their environments.”[2]

All biologists mean by stipulating that mutations are ‘random,’ therefore, is that the mutations do not aim toward (or away from) adaptive advantage. The biologist is clearly using the term ‘random’ in a very technical sense, just as the mathematician might use the term ‘random’ in a technical sense to characterize a certain set/series of numbers, and what the biologist means by this technical-theoretical term doesn’t seem to entail randomness in any sense which would preclude God’s providentially directing evolution. So, the question is, is there some deeper reason why this technical sense of ‘randomness’ does, after all, preclude God’s having a providential hand in evolution? Can this modest statement about biological randomness really purchase the metaphysically rich thesis that evolution was not (and could not have been) ‘guided’ by God? How could one cash-out such an incredible claim? Dr. Craig offers his thoughts:

“[Evolutionary creationists] would say that God has so set up the process that by chance alone these organisms will have evolved. Now… these folks would see the evolutionary process as under the superintendence of God and therefore is a guided process in that God allows it to function so as to arrive at his predetermined ends. Now, why can’t evolution be guided in that sense, in the sense that… the theistic evolutionist thinks of it? There the chance mutations and natural selection are within the broader purposes of God.

Well, what you discover when you read the evolutionary biologist is that of course they don’t deny that the process could be guided in that sense. That’s a metaphysical conclusion to which scientific evidence is irrelevant. What they simply mean is that the production of offspring does not occur with a view toward what will make these offspring survive better in the future, that there isn’t a kind of mechanism that produces offspring that will be well-suited to survival. Well, that’s perfectly within the purview of progressive creationism or theistic evolution. That’s a very limited, narrow, sense of guidedness that doesn’t need to be denied by the theistic evolutionist or progressive creationist. Suppose, for example, the [evolutionary] creationist thinks that the reason that God allows certain types of offspring to be produced is so that they will [become] easy prey for some other predator which he wants to flourish. Well in that sense, yes, it’s not guided with a view toward the survivability of the offspring – quite the contrary – the purpose is that they become prey for some other species or some predator. But the whole process is guided in this broader sense. So the problem here is that Miss Kirby [who thinks there is an incompatibility here] just has a philosophically superficial understanding of what it is to be guided, and the sense in which the evolutionary process is unguided is one that the theologian could affirm.”[3]

This seems pretty airtight to me, and nevertheless not everyone is convinced (on the far right or the far left). Casey Luskin, for instance, writes:

“Generally speaking, I find myself nearly always agreeing with Dr. Craig’s arguments. A few years ago I had the pleasure of watching Dr. Craig offer a compelling debate performance against Christopher Hitchens on “Does God Exist.” But on this issue of the nature of Darwinian theory, I find myself in a rare situation where I disagree with Dr. Craig.”[4]

I find this to be a frustrating situation; why aren’t these new atheists, or these evangelical creationists, convinced, as I am, by this reasoning? To answer that, I supposed I’d have to be a psychologist or a sociologist, or both. What I can do, as a philosopher, is try to come up with additional arguments which might help to change these people’s minds. Here is one such argument I’d like to present:

  1. If the theory of evolution were true, then physical determinism would be possibly true.
  2. If physical determinism were (even) possibly true, then God’s providential control over evolution would be possible.
  3. Evolution is true.
  4. Therefore, God’s providential control over evolution is possible.

It seems obvious to me that the theory of evolution is compatible with the theory of physical determinism; in fact, many naturalists who are strictly materialists or physicalists (and even some naturalists who aren’t) affirm both that physical determinism is true, and that the theory of evolution is true (which further reinforces what has already been said, namely that the technical sense in which evolutionary biologists use the word ‘random’ is compatible with other senses in which evolution might be guided or deterministic). However, suppose for the sake of argument that physical determinism is true (at least, if you like, up to the point of the appearance of the first creatures with libertarian free will), and that evolution is also true; why couldn’t God have so arranged the initial conditions under which the universe began to exist that he deterministically brings it about that evolution produces exactly what he intended it to?

Notice here that I am not claiming that physical determinism is in fact true (it seems to me rather dubious), but that it is possibly true, and that this possibility is enough to demonstrate the logical compossibility of evolutionary theory and God’s divine providential hand in directing the precise course of evolution. This seems to me to be a knock ‘em down drag ‘em out argument – I cannot even imagine what a (reasonable) critical rejoinder would look like, at least presuming that people are reasoning in approximately the way I imagined at the beginning of this post. I suspect that if some person remains unpersuaded by this argument, they won’t be persuaded by any argument, so that this is about as good as we can ever hope to do.

It may be worth saying a brief word about possible alternative arguments for the logical incompatibility of theism and evolution. Perhaps somebody could argue as follows:

  1. If God (being a maximally good, powerful and intelligent/rational being) had to choose between two different ways to bring about an effect, He would, ceteris paribus, elect to use the more efficient of the two means.
  2. Evolution is a means which is less efficient than other means which would have been options for God.
  3. Evolution is true.
  4. Therefore, God did not choose to actualize evolution.
  5. If God exists and Evolution is true, then God did choose to actualize evolution.
  6. Therefore, God does not exist.

The thought here is that a rational being always prefers, all things being equal, the more efficient of any two methods for achieving a given goal. This is a popular definition in economic theory, and sometimes makes an appearance in political philosophy. For instance, in his magnum opus,A Theory of Justice,” John Rawls characterized his idealized denizens of the ‘original position’ as rational in the following sense:

“… rationality must be interpreted as far as possible in the narrow sense, standard in economic theory, of taking the most effective means to given ends.”[5]

The trouble with this definition is well noted by William Lane Craig, to whom I will turn again. Craig has made the point numerous times that ‘efficiency’ can only be a value for a being with either (or both) limited time, or limited resources.[6] As God has neither limited time, nor limited resources, there is no reason to think God could value efficiency. So, as well as this definition may work in economic or political theory, it isn’t very useful theologically or philosophically.

Strictly speaking, I disagree with Craig, but I take his point to be a useful one to show that the presumption of the first premise in this argument seems to be false. I am inclined to think that God could value efficiency for aesthetic reasons, which would help to explain why parsimony, for instance, appears to be indicative of the truth of a theory, and not merely of its usefulness. There are puzzles in the philosophy of science about why parsimony would, on naturalism, make a theory any more likely to be true, whereas on Theism, at least if God values the aesthetic quality of simplicity, it may not be so surprising after all.[7] By analogy, consider that the elegance or beauty of a theory often seems to point to its truth, which seems an odd coincidence unless one is a Theist. Robin Collins has pointed out that beauty itself has been a seemingly useful indication of a scientific theory’s truth. He writes:

“To say that the beauty of the mathematical structure of nature is merely subjective, however, completely fails to account for the amazing success of the criterion of beauty in producing predictively accurate theories, such as Einstein’s general theory of relativity.”[8]

Admittedly parsimony needs to be carefully defined, and even if God does value parsimony it would presumably be in competition with other aesthetic values God might have (as any good engineer will tell you, the simplest way, on the face of it, is not always the best way). However, if God does value parsimony (and hence ‘efficiency’ in at least some cases) for aesthetic reasons, that may provide Him with a good reason to elect the more efficient of two otherwise equally good methods. Efficiency would only be valued to the degree that it allows for an optimal balance between itself and other aesthetic values. This caveat of mine does nothing, however, to take away from the effectiveness of Craig’s response in the case at hand. There simply is no reason whatever to think that evolution is not parsimonious enough that God might have elected to use it (and this is never-minding the theological/apologetic justifications for God’s allowing evolution).

Another argument might go as follows:

  1. Evolution is a process which involves gratuitous evil (evil for which there is no morally sufficient reason which God has for allowing in the world).
  2. God exists if and only if gratuitous evil does not.
  3. Evolution is true.
  4. Therefore, God does not exist.

Or

3.* God exists.
4.* Therefore, evolution isn’t true.

The trouble with this argument is that it is simply a version of the problem of evil, which comes in two forms; there is the so-called ‘logical’ problem of evil, and the ‘evidential’ problem of evil. As it stands today nobody thinks that the ‘logical’ problem of evil, which suggests that the existence of any evil is logically incompatible with the existence of God, stands any hope of being correct. Second, although there are significant problems with the evidential argument from evil, it is worth pointing out that if the above argument is intended to be a version of the logical problem of evil then it incontrovertibly fails, and if it is intended to be a version of the evidential problem of evil then it can be dealt with in all the standard ways in which all versions of the evidential problem of evil are dealt with. In other words, because ‘evolution’ as such is not an essential feature of this argument, but an accidental one, evolutionary theory plays no special role in the argument, implying that evolution as such poses no special challenge.

What other arguments could there be? Although there is always the possibility that there is some other clever argument to think that God’s existence and the theory of evolution are not compossible, an argument which I have never heard or thought of, still it seems unlikely that any such arguments exist or are forthcoming (and even more unlikely that they would be unanswerable). So, I think we can conclude with tremendous confidence that the theory of evolution is not only compatible with the existence of God, but also his divine providence.

[1] Francisco J. Ayala, “Darwin’s greatest discovery: Design without designer,” in Proceedings of the National Academy of Sciences USA, 104, no. Suppl 1 (2007): 8567-8573.

[2] Elliott Sober, “Darwin and Intelligent Design,” Lecture, the Sydney Ideas Lecture Series, The University of Sydney, Sydney Australia, April 22, 2010. http://fora.tv/2010/04/22/Elliott_Sober_Darwin_and_Intelligent_Design

[3] “Is Evolution a Threat to Christianity?” Narrated by William Lane Craig and Kevin Harris, ReasonableFaith Podcast, ReasonableFaith, December 5, 2011. http://www.reasonablefaith.org/is-evolution-a-threat-to-christianity#ixzz3RSURRy2s

[4] Casey Luskin, “Unguided or Not? How Darwinian Evolutionists Define their Theory,” http://www.evolutionnews.org/2012/08/unguided_or_not_1063191.html

[5] Rawls, John. “A Theory of Justice, rev. ed.” Cambridge, MA: Belknap 5 (1999): 12.

[6] See: “UFO’s” Narrated by William Lane Craig and Kevin Harris, ReasonableFaith Podcast, ReasonableFaith, August 17, 2008. http://www.reasonablefaith.org/ufos

[7] See Pruss: http://alexanderpruss.blogspot.ca/2014/03/simplicity-as-sign-of-design.html; http://alexanderpruss.blogspot.ca/2013/08/explaining-simplicity-of-theories.html; http://alexanderpruss.blogspot.ca/2013/07/why-prefer-simple-and-elegant-theories.html;

[8] http://infidels.org/library/modern/robin_collins/design.html