The Divine Architect

In the Origin, Darwin used a specific theological view of God's relationship to natural laws in order to argue for evolution and against special creation. An intimation of this view appeared in a passage Darwin chose from William Whewell's Bridgewater Treatise as an epigraph for the Origin:

More directly, Darwin wrote near the finale of the Origin,

In this passage, Darwin compared two theories in light of a claim about natural laws.Footnote ⁹ More exactly, he compared special creation and evolutionary theory to a background claim – what ‘we’ already ‘know’ about the laws of nature – in order to assess which theory best accorded with this background knowledge. Darwin reasoned that knowledge about the laws of nature favoured the ‘production and extinction’ of flora and fauna by ‘secondary causes’ rather than by independent acts of creation. This claim implied that the laws were unbroken – otherwise they could not favour purely secondary causes (and, hence, descent with modification) rather than miraculous causes (used in special creation).

But what justified the (implied) claim about unbroken law? While a full answer must take into account the Origin as a whole, including the role of natural selection, in this passage theology implicitly served as the immediate justification. Consider that, from an epistemic perspective, a naked appeal to the laws of nature alone was insufficient justification to favour secondary causes exclusively. At the time, many thinkers held that ‘a law presupposes an agent’, as Paley had famously said.Footnote ¹⁰ In traditional theism, this ‘agent’ both sustained the world in an orderly fashion and acted miraculously within the world; in this view, the two actions were not contradictory but rather complementary means of accomplishing the divine will. Thus Darwin had to give some justification for his claim that the laws of nature were unbroken – contrary to miracles – and thus favoured a biological theory that invoked only secondary causes.

Theology provided the edge. Laws were ‘impressed laws on matter by the Creator’. The language of ‘impressed’ laws, I would argue, suggests a picture of a Creator who, having once implemented these laws, allowed nature to act only by secondary causes. Consider, first, Darwin's endorsement of this view elsewhere. In his autobiography (which he originally intended only for his family), Darwin affirmed the dichotomy between laws and miracles: ‘the more we know of the fixed laws of nature’, he wrote, ‘the more incredible do miracles become’.Footnote ¹¹ He also claimed that nature operates by laws alone: ‘Everything in nature is the result of fixed laws’.Footnote ¹² Darwin's early notebooks reflected the same sentiments, privately endorsing divine creation by law as ‘far grander’ than specific instances of creation by miracle, which were ‘beneath the dignity of him, who is supposed to have said let there be light & there was light’.Footnote ¹³ And, in his 1844 manuscript, he added that ‘laws capable of creating individual organisms … should exalt our notion of the power of the omniscient Creator’.Footnote ¹⁴ Thus, in writings before and after the Origin, Darwin consistently rejected miracles and instead favoured unbroken natural law.

These emphases dovetail with the views of a number of Darwin's intellectual mentors, including William Whewell, John Herschel, Charles Babbage and Francis Bacon, who conceived of natural laws as God's primary mode of governing the physical world. For them, scientific explanations ought to refer to these laws rather than to miracles. These men were not deists – they believed God actively sustained the world by His laws – yet they considered appeals to secondary causes to be scientifically superior to reliance on miracles.Footnote ¹⁵

More directly, Babbage, Herschel and Whewell used the identical word – ‘impressed’ – in order to express the same idea of God inscribing matter with enduring, lawful qualities.Footnote ¹⁶ For example, in the Preliminary Discourse, Herschel wrote of the raw materials of the universe: ‘by creating them … endued with certain fixed qualities and powers, he has impressed them in their origin with the spirit … of his law, and made all their subsequent combinations and relations inevitable consequences of this first impression’.Footnote ¹⁷ And Whewell declared in his Bridgewater Treatise,

This statement occurs in the same paragraph as the claim Darwin borrowed from Whewell as an epigraph to the Origin, which stated that God does not work by discrete miracles but rather ‘by the establishment of general laws’. Whewell went on in the next two paragraphs to quote Francis Bacon and Herschel to the same effect, citing the Herschel quote above.Footnote ¹⁹

As such, ‘the Creator’ who ‘impressed laws on matter’ was not the God of special creation, but of unbroken law. From an epistemic point of view, Darwin's argument only made sense with this understanding of the deity. An allusion to a Master Architect rather than a Miracle Worker provided the justification for unbroken laws, and these laws allowed only secondary causes, which favoured evolution over special creation. Theology thus played a subtle – yet pivotal – role in this argument for evolution and against special creation.

Of course, Darwin's appeal here is indirect rather than straightforward, requiring a fair amount of interpretation. The Origin's language is understated and artfully ambiguous, one might say. Little surprise that Darwin's contemporaries differed on whether descent with modification was reconcilable with traditional theism's understanding of the laws of nature and, especially, God's providence over organic history.Footnote ²⁰ But despite this disagreement, Darwin's appeal to law had epistemic import only if these laws were conceptualized in a Herschelian and Whewellian manner rather than in a special-creationist one.

To be sure, there is some ambiguity in the Origin about unbroken law in the history of the cosmos; three times in the closing pages, Darwin nodded toward the miraculous creation of the first life.Footnote ²¹ In the second edition, Darwin even added that life was first breathed ‘by the Creator’.Footnote ²² While there is good evidence that Darwin was a deist in 1859,Footnote ²³ the Origin itself inconsistently seemed to accept and reject miracles. This apparent tension will be taken up later; for now, I will refer to the theology of the Origin as semi-deistic.Footnote ²⁴

A number of scholars have recognized the link between natural laws and theology in the Origin.Footnote ²⁵ John Cornell argues, for example, that the volume portrayed the physical world as the product of a ‘divine arrangement of universal laws’, a view that arose from Darwin's early convictions about God's limited role in the natural world.Footnote ²⁶ Robert Richards writes of Darwin in the Origin, ‘Yet in this work of twenty-years maturation, he continued to suggest that the laws of evolution, those secondary laws, ought best be conceived as God's commands’.Footnote ²⁷ And David Kohn observes not just a connection between Darwin's view of natural laws and his theology, but that Darwin regarded his theology as more venerable than creationist theology:

As a brief addition, it is arguable that Darwin's deism shaped the Origin at a more fundamental level as well. I have maintained above that his view of God's limited action played a role in his argument for evolution (and against special creation), but it may also have influenced the content of his theory itself. The process of natural selection acting upon random variations lies at the centre of Darwin's theory. A deistic theology – rather than an interventionist theology – readily sanctions this process which does not rely on God's direct hand but on environmental pressures, competition, random variation and inheritance.Footnote ²⁹ In the 1830s, ‘Darwin started on the path to evolution’, Michael Ruse concurs, ‘perhaps because he was now thinking of God as someone Whose greatness is evidenced by unbroken law rather than by miracle’.Footnote ³⁰ A distant Creator commended a process of purely secondary causes, the very heart of his nascent theory.Footnote ³¹

In sum, theology provided epistemic aid to evolution by its use of unbroken law and perhaps also shaped the content of evolution by endorsing a naturalized means of biological change. Apparently, the Origin did not dispense with God-talk so much as harmonize science with the ‘right’ understanding of the deity.

The problem of natural pain and suffering

Darwin found evidence for his theory in, of all places, pain and suffering. Three years prior to the Origin, Darwin wrote to a colleague, ‘What a book a devil's chaplain might write on the clumsy, wasteful, blundering, low, and horribly cruel works of nature!’Footnote ³² To Darwin, the problem of pain was no mere academic difficulty. In a personal letter, he wrote that he suffered a ‘bitter and cruel loss’ when his daughter Annie – whom he described as his ‘favourite child’ – died at age ten in 1851.Footnote ³³ Even twenty-five years after Annie's death, Darwin confided, ‘Tears still sometimes come into my eyes, when I think of her sweet ways’.Footnote ³⁴ As a number of scholars have argued, the problem of suffering informed Darwin's science.Footnote ³⁵ In the Origin, Darwin argued that suffering itself was evidence for his theory: since natural suffering is more compatible with evolutionary theory than with special creation, it counted as evidence in favour of evolution. In the final sentence of his chapter on the evolution of instincts, for example, Darwin closed with the following meditation:

In the final chapter of the Origin, in which Darwin recapitulated his chief arguments, he noted that, given his theory, we should not be surprised

Years later, in his autobiography, he echoed a similar view, remarking that ‘the existence of suffering’ counts ‘against the existence of an intelligent first cause’ but ‘agrees well with the view that all organic beings have been developed through variation and natural selection’.Footnote ³⁸ As John Brooke observes, ‘The presence of so much pain and suffering in the world Darwin considered to be one of the strongest arguments against belief in a beneficent God. But, he added, it accorded well with his theory of natural selection’.Footnote ³⁹

Darwin's key claim in these passages is that some instances (or amounts) of natural suffering are more expected given his theory than given special creation.Footnote ⁴⁰ In his view, only through an intense struggle for survival do species adapt and flourish, so it is no surprise that less-fit organisms perish along the way. This pattern of death and cruelty is less expected given special creation, which (as Darwin saw it) posits a benevolent, all-powerful, all-knowing God who designs creatures to adapt and flourish in their local environments. Darwin implicitly invoked what has been called the ‘prime principle of confirmation’, in which evidence counts more in favour of theory A than of theory B if the evidence is more probable (or more expected) given theory A than given theory B.Footnote ⁴¹ Thus the presence of natural suffering counted more as evidence in favour of evolution than of special creation, since suffering was more probable given evolution than given special creation.

The argument relies on the theological assumption that it is improbable that an omnibenevolent, omnipotent and omniscient God would have intentionally designed creatures to cause or experience great suffering.Footnote ⁴² Despite a host of traditional theodicies which sought to reconcile God and natural suffering, Darwin implied that the special creationists’ conception of God was simply implausible given such misery. Thus the Origin tacitly endorsed a particular view of God's nature and moral obligations, and used this view as direct epistemic support for evolution and against its primary rival.

Arguably, at a deeper level, Darwin's theological struggles with suffering did not simply provide evidence for his theory but also shaped its content as well. Recall the quote from the Origin (above), in which Darwin stated that instances of natural suffering are ‘small consequences of one general law, leading to the advancement of all organic beings, namely, multiply, vary, let the strongest live and the weakest die’.Footnote ⁴³ In this passage, he characterized the work of variation and selection as leading to ‘the advancement of all organic beings’.Footnote ⁴⁴ Natural suffering, apparently, was acceptable collateral damage in a process that ultimately produced a higher, better outcome. God designed the laws of nature in keeping with his moral nature: these laws led to progress so that the final end justified any suffering along the way. Natural selection thus insulated God from the suffering so troubling to special creation; it exonerated God from direct responsibility for natural suffering while also ensuring that the struggle for existence led to a morally acceptable end.Footnote ⁴⁵ Thus Darwin's theology sanctioned his theory. The belief in a distant, yet moral, God required a means of creation that could account for the presence of natural suffering in a manner consistent with God's character. Variation and selection, with their progressive element, provided just that.

The only wise (and inventive and parsimonious) God

Darwin's famous argument from homology also hinged upon theology.Footnote ⁴⁶ In the Origin, Darwin considered the similar pattern of bone structures in the hand of a man, paw of a mole, leg of a horse and paddle of a porpoise. Special creationists claimed that each of these structures served a highly functional purpose (or even an optimal one) and thus reflected the species-specific design plan of a wise Creator. Darwin wanted to convince his readers that evolution by natural selection provided a superior explanation. To this end, he aimed an attack squarely at his rival:

Both here and elsewhere in his homology argument, Darwin drew primarily from On Limbs (1849), a work by Richard Owen, perhaps the leading comparative anatomist of the time.Footnote ⁴⁸ Because Darwin not only invoked the authority of On Limbs, but also cited it directly in his central attack on special creation,Footnote ⁴⁹ a close analysis of the work is in order. Careful inspection reveals that, in addition to empirical evidence, Owen used theological claims to reject final causes (or direct divine purposive adaptations) as explanations for homologous structures. To appreciate this, consider one of Owen's central axioms, stated early in On Limbs:

In short, human inventors fashion their various locomotion machines ‘expressly and immediately’ for the particular purpose of each machine. Inventors do not employ a common design for all machines, attempting to innovate new functions while also rigidly accommodating a universal plan.

Owen contended that the special creationist (or ‘teleologist’) held that God created in the same manner: ‘The teleologist’, he asserted, ‘would … expect to find the same direct and purposive adaptation of the limb to its office as in the machine [invented by humans]’.Footnote ⁵¹ Thus, just as humans do not invent locomotive machines from a common type, but rather directly for specific purposes, so God created limbs at the species level de novo for specific environments, rather than modifying a more general type. As philosopher Paul Nelson observes, the underlying assumption is, ‘If the creator is free to do as he pleases, the appearance of [a] plan can become the appearance of limitation or constraint, suggesting an unimaginative or even slavish repetition of structures along some predetermined pattern’.Footnote ⁵² Owen assumed that the ‘apparent uniformity of certain biological patterns is inconsistent with the freedom of a creator to act as he wishes’.Footnote ⁵³ An unconstrained God, Owen presumed, would always start from scratch.Footnote ⁵⁴

It is precisely this assumption that Owen used to drive home his attack on special creation. He argued extensively in On Limbs that different species sometimes do have limbs that share a common type or ‘unity of plan’.Footnote ⁵⁵ As he saw it, these limbs manifested characteristics precisely opposite to those predicted by special creationism. Thus Owen's criticism can be represented as a modus tollens:

1. 1 If special creationism is true, then limbs of organisms will not manifest a common type beyond the species level.

2. 2 But some limbs of organisms manifest a common type beyond the species level.

3. 3 Thus special creationism is not true.

At a minimum, Owen's argument can succeed only if an assumption essential to premise 1 is true – namely that the God of miracles always creates afresh rather than by drafting off a general plan. It is true that special creation held that God expressly and directly created organisms, organs and limbs at the species level to match particular environments. But the theory did not logically prohibit God from starting with or incorporating a common design plan, modified for the functional requirements of a new species in a new environment. This latter idea was Owen's addition, allowing him to use his empirical evidence to counter special creation.

Elsewhere in On Limbs, Owen continued his subtle deployment of theology. At the end of his first detailed analysis of appendages, about forty pages into the work, Owen self-consciously stepped back to make his argument against special creationism clear:

In this dense passage, Owen made two central claims. First, the similarity of bone structure between a human hand (and arm) and ‘the fin of the whale’ does not harmonize with ‘our idea of the simplest mode’ of producing a functional fin. Second, the ‘great number of bones in the cranium of the chick’ exceeds the physical ‘requirements’ necessary for hatching from an egg (‘the act of exclusion’).

Taking these claims in order, recall that special creationism held that God directly and expressly created organisms’ limbs for specific adaptive purposes at the species level. This meant that God directly and expressly created the whale's fin for the purpose of locomotion in water. But Owen rejected this view because the whale's fin had the same basic bone structure as a human hand and arm – which was too elaborate, in Owen's mind, for what was ‘required’ for the function of a simple ‘undivided and inflexible paddle’. An over-engineered fin ‘squares little with our idea of the simplest mode’ of outfitting the fin for its purpose. That is, the special-creationist explanation failed because it did not harmonize with a human conception of (superlative) simplicity – the ‘simplest mode’ of creating. In short, any plausible view of divine creativity must accord with human notions of parsimony.Footnote ⁵⁷ While Owen was not clear on exactly what constituted the ‘simplest mode’ of creation, his view seemed to imply that God would be restrained, producing only the minimum internal structure necessary for the paddle's outward function. (This is why Owen disparaged the idea that a complex bone structure was ‘required’ for the paddle's simple purpose.)

Owen's second claim in the passage reinforced the appeal to parsimony. The great number of bones in the cranium of the chick does not square with the ‘requirements’ for hatching from an egg. By Owen's lights, a respectable God would not produce a skeletal structure – whether in the whale's fin or the chick's head – more intricate than needed to accomplish the structure's function. In short, God fashioned organic parts as simply as possible for their purpose. Surprisingly, Owen gave neither evidence nor argument for the theological assumptions in this passage,Footnote ⁵⁸ perhaps because he regarded them as uncontroversial. Good Victorians knew, apparently, that the Almighty was no prodigal.

It may be that Owen personally accepted the theological assumptions he used to attack special creation. But Owen's personal views are irrelevant for present purposes. What matters is that he utilized the claims above as part of his case against special creation (and for non-material archetypalism). These claims included: first, that a God who is free to create as He wishes would create new biological limbs de novo rather than from a pre-existing pattern. Second, that God must create biological structures (like limbs) in accord with a human conception of the ‘simplest mode’ to accomplish the respective functions of these structures. And third, that God would only create the minimum structure required for a given part's purpose. One might wonder whether Owen had subconsciously gilded God to resemble the archetypal Victorian gentleman – who is at once ingenious and industrious, yet sensibly temperate. In any case, these positiva additions enabled Owen to test the alleged predictions of special creation and so use his detailed empirical observations to their fullest advantage.

When Darwin invoked Owen to attack special creation, he implicitly relied upon this same line of reasoning in order to make his homology argument succeed. In fact, Darwin drew on the exact passage explored above, explicitly citing Owen's example of bird craniums.Footnote ⁵⁹ Moreover, Darwin incorporated Owen's ideas into a passage in the Origin that is arguably Darwin's primary direct assault on special creation's account of homology. In this passage, Darwin asked four key rhetorical questions designed to undermine special creation, each of which presupposed one or more of the positiva assumptions imported from Owen.Footnote ⁶⁰

Whether Darwin was consciously aware of the theological commitments contained in Owen's work is quite beside the point. Epistemologically, Darwin needed these theological claims in order to use Owen's argument effectively in crippling special creation. Remove the theology and little substance remains. For example, if one allows that God could design organisms ‘by adjustment’, modifying previous designs in order to accommodate the functional requirements of new organisms, then one need not accept the de novo premise. And, if one allowed that God's creative ways did not always conform to human notions of the ‘simplest’ method, then one could discard another of Owen's central assumptions. A similar criticism could be raised for the remaining theological claim. But the truth of these claims (or their criticisms) is irrelevant. The key point is that Owen's positiva theology critically supported his attack on special creation. By extension, Darwin's own assault also relied on theology.

Positiva theology not only helped Darwin assail special creation, it also helped him establish descent with modification. Since Darwin framed the Origin primarily as a contest between special creation and descent with modification, a successful attack on the former implied that the latter emerged as the de facto victor. Thus theological claims indirectly gave positive epistemic support to Darwin's homology argument for evolution. None of this is to say that theological premises are the only important premises in the argument; in their assessments of the doctrine of final causes, both Owen and Darwin drew on carefully established empirical data about homologies. Yet, as we have seen, theological assumptions were essential to Owen's case and, by extension, to Darwin's case as well.

The homology argument played no small role in the Origin's overall polemic for descent with modification. In the Origin, Darwin introduced homology by declaring that it fell under morphology, ‘the most interesting department of natural history, … [which] may be said to be its very soul’.Footnote ⁶¹ The correct account of homologous structures would thus give insight into the heart of organic history. And in personal correspondence in 1860, Darwin noted that, along with embryology, homology provided nearly enough ground alone to ‘disbelieve in the innumerable acts of creation’.Footnote ⁶² In fact, the significance of the homology argument is reflected in its longevity; in the present day, this argument – along with its theological substance – is routinely cited as important evidence for evolution.Footnote ⁶³

In sum, Darwin not only used theology as part of his direct apologetic for evolution, but did so in an argument which he regarded as significant to his overall case for descent with modification.

Divine honesty

The God of the Origin did not leave deceptive marks upon the natural world. More exactly, Darwin suggested that the Almighty did not create organisms that, when studied, indicate false information about their origins; instead, the information gleaned from these organisms could be taken as providing reliable clues to their beginnings. This particular idea appeared in all six editions of the Origin and in personal correspondence.Footnote ⁶⁴ Darwin also made similar remarks in an early notebook, in the 1842 sketch, in the 1844 manuscript and in Descent of Man, although in these works he did not tie the ‘truthfulness’ of nature explicitly to the deity.Footnote ⁶⁵

In Chapter 5 of the Origin, Darwin noted that, in some cases, horses will produce offspring that resemble the markings of a foreign species of horse more than the markings of their own species. Likewise, hybrids sometimes resemble foreign species of the horse genus more than their own parental species.Footnote ⁶⁶ Darwin stated that these tendencies could be readily explained by an ancient ancestor who shared traits common to all species in the horse genera. On the other hand, he saw these facts as a problem for special creation because, in that view, God created each species independently such that ‘like follows like’ – offspring should resemble their parental species rather than a foreign species. Special creation seemed to have an empirical problem: the observable data conflicted with a straightforward prediction of their view. However, Darwin noted that creationists could account for this anomaly by asserting ‘that each species has been created with a tendency to vary, both under nature and under domestication, in this particular manner, so as often to become striped like other species of the genus’.Footnote ⁶⁷ That is, creationists could adjust their theory by saying that God designed some purebred and hybrid offspring with a predisposition to resemble other species of the horse genus. Thus while the tendencies of horse variation seem to be clearly explained by common ancestry, the (modified) creationist explanation could account for the data by holding that God had designed horse variation in a manner that appeared to be exactly what one would expect if common ancestry were true. God had hidden His direct hand.

To contemporary ears, this may seem as if special creationists had simply invoked an all-powerful God to accommodate, rather than explain, data that should be regarded as a problem for their theory. But contemporary sensibilities aside, Darwin's own response is telling. In the very next sentences, he wrote,

Darwin's reference to the ‘ignorant cosmogonists’ is likely an allusion to the work of select palaeontologists from a previous era who had argued that God created some natural artefacts, like fossils, to appear older than they actually were.Footnote ⁶⁹ Darwin regarded such an explanation as unacceptable. Apparently following his vera causa scruples, he protested that this creationist explanation relied on an ‘unreal’ or ‘unknown’ cause because there was no independent evidence (or present experience) to think that God created in a manner which disguised His involvement.Footnote ⁷⁰ The special-creation account held that the unusual features of certain horses were actually the result of a divine miracle when they appeared to be the result of evolution from a common ancestor. Accordingly, a careful empirical study of these horses could not provide accurate information about their origins. More generally, this implied that empirical data about an organism could not be trusted to give accurate information about its natural history. The creationist explanation rendered the empirical data itself unreliable. This meant that scientists could no longer trust empirical data, which cast the scientific enterprise itself into doubt.

But why did Darwin not simply end the matter by using his vera causa principles to claim that the creationist explanation ‘makes the empirical evidence a mere mockery and deception’? Instead, he wrote that the creationist explanation ‘makes the works of God a mere mockery and deception.’Footnote ⁷¹ The reason, I would argue, is that Darwin wanted to drive home the reliability of the empirical evidence by linking it to God's moral character. The creationist explanation was mistaken not just because it violated the vera causa requirement but, more fundamentally, because it disparaged God's honesty – the very thing which sanctioned the trustworthiness of scientific data. God's probity meant that the data could be trusted to yield straightforward information; thus, if horses appear to have arisen from a common ancestor, then they had arisen from a common ancestor. For Darwin, divine integrity was a crucial factor that favoured the evolutionary account over the special-creation account.

Moreover, God's probity showed why the vera causa requirement could not be fulfilled by special creation: there could be no independent evidence (or present experience) of spurious empirical ‘facts’ because a moral God would allow no such thing. More generally, the reliability of empirical data was now beyond reproach – in effect, science itself was possible because God was no deceiver.

The textual evidence spanning from Darwin's early notebooks to Descent of Man makes it difficult to discern whether or not Darwin personally held this belief. As mentioned, he repeatedly claimed that nature is non-deceptive, but only tied this claim to the deity in the Origin and in private correspondence. Even so, the present point is not to analyse Darwin's personal theological beliefs but rather to examine the epistemic role that theology played in the first edition of the Origin. On this latter point, Darwin clearly used theology in the Origin in order to strengthen his position.

It is important to emphasize that, in this instance, the evolutionary and creationist explanations were at an empirical standstill: strictly speaking, both could account for the unusual data about horses. Scientific evidence was plainly impotent to settle the dispute. Instead, Darwin turned to the heavens, citing God's moral probity as the adjudicating factor. Rightly or wrongly, Darwin used God's (alleged) non-deceptive character as more than just a mooring for a general philosophy of nature; it functioned as direct epistemic support for descent with modification.Footnote ⁷²

In sum, Darwin deployed God-talk to favour evolution over special creation in an instance in which, to his mind, neither empirical data nor vera causa requirements (alone) were adequate. In this case, an extra-empirical criterion provided vital support to his argument – and this criterion, surprisingly, centred on God's integrity. By extension, divine integrity also ensured the reliability of empirical data and, hence, science itself.

The inscrutable God

In Darwin's time, the argument for biological design had received its most rigorous formulation from William Paley, who had argued in Natural Theology (1802) that the intricate adaptation of organs and organisms to their environment implied divine design rather than chance material processes. Arguably, one of the high points of Paley's work was his design argument about the vertebrate eye. ‘I know no better method of introducing so large a subject’, he explained,

From here Paley went on to detail the various structural and functional adaptations of the eye to its environment, why the eye and telescope were appropriately analogous, and why this implied that the eye, like the telescope, was designed. No stranger to Paley's views, Darwin had studied Paley's Natural Theology and Evidences of Christianity as a student at Cambridge, recalling later that both ‘gave me as much delight as did Euclid’, a favourite author. And, just two weeks prior to the publication of the Origin, Darwin wrote to a colleague that ‘I do not think I hardly ever admired a book more than Paley's Natural Theology. I could almost formerly have said it by heart’.Footnote ⁷⁴

Moreover, since his notebooks of 1838, Darwin openly struggled with how to account for the eye by purely secondary causes.Footnote ⁷⁵ As Abigail Lustig observes, the development of the vertebrate eye was one of the chief difficulties for Darwin's theory as well as one of the ‘classical examples’ of natural theology, giving him clear impetus to focus on it in his case for evolution in the Origin.Footnote ⁷⁶

Unsurprisingly, Darwin's response to Paley's eye argument became a ‘centrepiece’ of a chapter dedicated to addressing the strongest objections to evolutionary theory.Footnote ⁷⁷ Darwin noted that it seemed prima facie ‘absurd in the highest possible degree’ that an organ as intricate as the eye ‘could have been formed by natural selection’.Footnote ⁷⁸ Instead, he wrote,

Darwin offered two questions as an immediate reply, writing in the very next sentences, ‘But may not this inference be presumptuous? Have we any right to assume that the Creator works by intellectual powers like those of man?’Footnote ⁸⁰ Although Darwin's brevity makes interpretation difficult, his questions implied that the analogy between humans and God broke down. Human beings, he proposed, cannot know that their own causal powers are relevantly similar to the Creator's causal powers. Apparently, such knowledge was beyond human ken.Footnote ⁸¹ Darwin asked rhetorically what ‘right’ humans have for this analogy – that is, what sound basis was there to think that human beings can know such a thing about God's ‘intellectual powers’? His questions suggested that justification for the vertebrate-eye argument failed because certain features of God's nature, such as His creative power, were inaccessible to human beings.Footnote ⁸² Thus Darwin's negative rebuttal of the vertebrate-eye argument consisted of unmistakable theological ideas about human epistemology.

By way of a positive alternative to Paley's eye argument, Darwin stated that extant vertebrates offered meagre evidence for this theory and that the fossil record yielded none.Footnote ⁸³ Instead, he used the variations in extant invertebrates to construct an account of how the eye might have developed historically in vertebrates, suggesting that this scenario provided sufficient grounds to believe that an organ as ‘perfect as the eye of an eagle might be formed by natural selection’ even if one ‘does not know any of the transitional grades’.Footnote ⁸⁴ Darwin also wrote that rudimentary light-sensitive nerves could have slowly evolved into complex organs over vast years of slight, inheritable, advantageous variations preserved by natural selection. More generally, Darwin cited the claim that the lungs of vertebrates were originally a ‘floating apparatus or swimbladder’ for an ancient organism ‘of which we know nothing’ as key evidence for the incremental development of complex organs.Footnote ⁸⁵ These arguments, Darwin thought, would persuade a fair-minded reader who remembered that ‘his reason ought to conquer his imagination’.Footnote ⁸⁶

Curiously, Darwin's scenarios included very little reasoning about concrete empirical evidence. Historian Peter Dear observes that, despite Darwin's rhetoric to the contrary, his account actually conscripts reason in service of imagination. ‘Darwin's attempts to persuade … use reason to explore ideas that have first been conjured up by the imagination’, Dear explains. ‘The role of reason is really to enable a leap from ordinary imagination to the literally unimaginable’.Footnote ⁸⁷ In a similar vein, rhetorician David Depew regards Darwin's argument as a ‘thin thought experiment’ designed to sway a Victorian audience about the efficacy of natural selection.Footnote ⁸⁸

Despite the idiosyncrasies of this passage, however, it is important to recall that Darwin's full reply to Paley's theistic creationism is contained in the Origin as a whole rather than in this particular section of text. Natural selection functions as Darwin's central substitute for Paley's watchmaker, and the Origin details an extensive case for Darwin's blind watchmaker, drawing on an array of empirical evidence. So, one must weigh Darwin's particular response to Paley's vertebrate-eye argument against the backdrop of the Origin as a whole.

Even so, natural selection was meant to explain even complex organs. The case for natural selection may have been more than its account of the vertebrate eye but it was certainly not less. The path to victory had to pass through Paley's full gauntlet. And arguably a strong point of Paley's position was the vertebrate-eye argument, to which Darwin provided almost no concrete empirical rebuttal. Thus, at the sharp edge of Paley's sword – where the design argument was most cutting – Darwin parried with imaginative speculation and theology-laden epistemology rather than strong empirical evidence. In particular, Darwin's direct rebuttal of Paley, which emphasized the inaccessibility of God's creative powers, owed more to theology than to science.

A number of historians have recognized that Darwin's response to Paley's argument had deep personal and theological roots. Historian James Moore perceptively notes that there is a touch of piety in the humble manner in which Darwin approached metaphysical and theological questions.Footnote ⁸⁹ John Brooke observes, ‘When Darwin did vent his spleen against the apologetic thrust of natural theology, it was usually because he was taking exception to the arrogance, as he saw it, of those who considered themselves privy to God's purposes’.Footnote ⁹⁰ And John Cornell argues that a ‘theological thread runs through’ Darwin's counter to Paley, a thread that was to Darwin's mind ‘compatible with a more sublime theology’.Footnote ⁹¹ In the Origin, Darwin apparently drew upon this ‘more sublime theology’ to hold meekly that God's creative powers were opaque to humans. Once again, he commissioned theological claims to strengthen his naturalized account of organic history.

Tensions within the theology of the Origin

We may now step back from analyses of particular theological threads in the Origin to look at the tapestry as a whole. Perhaps surprisingly, Darwin's ‘muddle’ about theology, which he acknowledged later in life,Footnote ⁹² was subtly present in the first edition of the Origin, manifest as a pattern of vagueness, logical incoherence and epistemic illegitimacy. In order to establish this claim, this section will be more evaluative than previous sections, but it will do so ‘from the inside’; not by importing ‘external’ views opposed to Enlightenment-style theology, but by taking the Origin's theology on its own terms, analysing it for internal logical consistency as well as harmony with Darwin's mature reflections.

The first tension, mild in nature, concerns the Origin's apparent acceptance and rejection of miracles. If the interpretation earlier in the essay is correct, then, in a discussion of what ‘we know about laws impressed on matter by the Creator’, the Origin tacitly endorsed unbroken natural law as the sole means of the ‘production and extinction of the past and present inhabitants of the world’.Footnote ⁹³ However, elsewhere Darwin explicitly wrote that ‘life was first breathed’ into ‘one primordial form’, suggesting a miraculous origin of life.Footnote ⁹⁴ Advocacy of both broken and unbroken natural law may suggest an underlying conflict. However, a charitable interpretation proposes that the Origin articulated a semi-deism in which God originally impressed the laws of nature onto matter and later directly created the first life, but then let unbroken natural law govern the unfolding of organic evolution. This is a coherent position, but one which raises uncomfortable questions about whether a God who intervened once to create life might not so do again.Footnote ⁹⁵

These were murky waters. Darwin's strategy, consciously or otherwise, was to avoid clarifying the matter. Vague God-talk had the disadvantage of blurring the true theological moorings and implications the Origin's new science; it had the considerable advantage, however, of allowing deists and theists to interpret the Origin in the image of their own gods, making evolution by natural selection appear more persuasive. In this case, perhaps Darwin ignored theological clarity for the larger purpose of scientific success.

A second tension arises regarding the epistemic value of natural pain and suffering in the case for evolution. As we have seen, Darwin argued that, while no logical deduction could be made, pain and suffering counted as evidence for descent with modification rather than for special creation. Darwin also spoke of a ‘Creator’ who impressed laws onto matter, but did not perform miracles in organic history subsequent to the first life. Apparently, a remote God who allowed nature to operate by ‘one general law’ for the ‘advancement of all organic beings’ was not culpable for natural pain and suffering, unlike a God who deliberately designed organisms within organic history.

But one might wonder, ‘what if the Origin's Creator was omniscient?’ This God would know that the ‘general law’ in which ‘strongest live and the weakest die’ would include innumerable cases of agony and extermination, and thus might plausibly be said to be no less culpable than the God of special creation.Footnote ⁹⁶ These are deep matters, of course, and the task here is not to impose an ‘external’ criticism on Darwin's argument but, in this case, to consult his mature ruminations. Surprisingly, he effectively conceded the point in a letter to M.E. Boole in 1866:

By 1866, Darwin apparently believed that pain and suffering were not more compatible with the existence of an omniscient God (who let evolution unfold by general laws) than with the God of special creation.

But the Origin itself was unclear on this matter. Strictly speaking, Darwin did not refer to the deity in the 1859 edition as omniscient.Footnote ⁹⁸ But to many readers, his reference to a ‘Creator’ would plausibly be understood this way, absent any qualifications. (Indeed, in his 1844 manuscript he explicitly referred to an ‘omniscient Creator’.Footnote ⁹⁹) In any case, if Darwin's mature reflections are correct, then the Origin's vagueness about the omniscience of God obscured exactly how natural suffering favoured descent with modification over special creation. The offence here is not the mortal sin of logical inconsistency but rather the venial sin of imprecision. At a personal level, in 1859, Darwin was troubled in many ways by natural suffering, but at a rhetorical level, it also offered too powerful a weapon to leave aside. The primary purpose of the Origin was to establish descent with modification and undermine special creation. In the case of natural suffering, theology played a role in this greater objective, with little attention given to whether, in the end, it could legitimately accomplish the task.

A third and more serious difficulty concerns the logical incompatibility of some of the Origin's theological statements. For example, in his reply to Paley's vertebrate-eye argument, Darwin asked rhetorically, ‘Have we any right to assume that the Creator works by intellectual powers like those of man?’Footnote ¹⁰⁰ The claim asserts that human beings are not justified in believing that God operates in ways analogous to the intellectual powers of the human mind. However, in his homology argument, Darwin implied, following Owen's lead, that God creates in ways that accord with human notions of simplicity. God would not fashion certain biological structures from a common type, posited Owen, because this ‘squares … little with our idea of the simplest mode’ of creating these structures to fulfill their function.Footnote ¹⁰¹ Collectively, then, Darwin claimed, first, that human beings cannot know that God creates in ways analogous to the intellectual powers of the human mind, and, second, that God creates in ways that harmonize with the human conception of the simplest method of creating.

Add to these claims the plausible assumption that, at least in some contexts, notions of (superlative) simplicity very likely shape how human beings think and, in particular, how they create new inventions or theories. These three statements are jointly incoherent. They imply that humans can both know and not know that God's creative methods correspond with human conceptions of superlative simplicity. The Origin effectively dispatched Paley and deployed Owen only at the cost of fragmenting internally.

The most severe tension, however, can be found in the fundamental justification for all the positiva theological claims in the Origin.Footnote ¹⁰² Judged from an epistemic point of view, these claims offer genuine support for descent with modification only if they are justified in the first place. In this vein, one may ask, ‘if Darwin's own theory is true, what justification is there for the positiva theology he used to support his theory?’ To appreciate his query, consider Darwin's own reflections in his autobiography that he felt

This question, in one form or another, haunted Darwin from at least around 1859 to the end of this life.Footnote ¹⁰⁴ Just six months after the debut of the Origin, Darwin wrestled with the relationship between God and evolution in a letter to Asa Gray, writing that he believed in divinely designed laws with the details left to chance. ‘Not that this notion at all satisfies me’, Darwin immediately added. ‘I feel most deeply that the whole subject is too profound for the human intellect. A dog might as well speculate on the mind of Newton’.Footnote ¹⁰⁵

In Darwin's view, the human mind was not designed by God in order to know God; it was instead equipped by nature to cope with the survival and reproductive needs of ancient hunter-gatherers on the African landscape.Footnote ¹⁰⁶ Indeed, in Descent of Man, in which Darwin applied evolutionary theory to the human species, God did not fashion the human mind, but rather the reverse: Darwin argued that religious beliefs, including the monotheistic concept of God, arose due to a combination of abstraction, anthropocentric projection and social utility.Footnote ¹⁰⁷

But what of the positiva theological claims in the Origin itself? It seems that if Darwin had applied evolutionary theory to himself while writing the Origin, then he would not have been justified in his claims about God. Here, the looming problem comes to a head: by his own lights, if evolution is true, then some of the reasons for this theory – the homology argument, the natural-suffering argument, claims about divine honesty and about God's relationship to the laws of nature, and so on – are no longer justified.Footnote ¹⁰⁸ In effect, the theology of the Origin undermined itself.

Darwin was still entitled to use reductio theology, in which he simply took special creation's theology seriously in order to test its empirical predictions. (One can test a claim – say, that the Earth is flat – without having justification for that claim.) But if his mature reflections are correct, then positiva theology, which purported to be independent support for his theory, was an epistemic failure.

In summary, by taking seriously the laws of logic as well as Darwin's mature thoughts, an analysis of the Origin's theology reveals vagueness, logical incoherence and epistemic illegitimacy. Darwin's later theological ‘muddle’ was quietly present in 1859. In this view, the theology of the Origin resembles an assortment of claims that – even if some were existentially important to Darwin – do not appear, from an epistemic point of view, to have been carefully scrutinized for plausibility, clarity or consistency, but rather were recruited to satisfy the primary purpose of establishing evolution and undermining its chief rival.

Summary and conclusion

We may now step back and take stock of the claims advanced in this essay. I have argued that, in the first edition of the Origin, Darwin drew upon at least the following positiva theological claims in his case for descent with modification (and against special creation):

1. 1 Human begins are not justified in believing that God creates in ways analogous to the intellectual powers of the human mind.

2. 2 A God who is free to create as He wishes would create new biological limbs de novo rather than from a common pattern.

3. 3 A respectable deity would create biological structures in accord with a human conception of the ‘simplest mode’ to accomplish the functions of these structures.

4. 4 God would only create the minimum structure required for a given part's function.

5. 5 God does not provide false empirical information about the origins of organisms.

6. 6 God impressed the laws of nature on matter.

7. 7 God directly created the first ‘primordial’ life.

8. 8 God did not perform miracles within organic history subsequent to the creation of the first life.

9. 9 A ‘distant’ God is not morally culpable for natural pain and suffering.

10. 10 The God of special creation, who allegedly performed miracles in organic history, is not plausible given the presence of natural pain and suffering.

I have further argued that Darwin utilized theological claims in the Origin to provide epistemic support for descent with modification (and against special creation) in at least the following ways:

1. 1 as a crucial background claim that helped adjudicate between his theory and a rival theory;Footnote ¹⁰⁹

2. 2 as the primary factor that eliminated a rival theory in a case in which Darwin's theory and a rival were at an empirical stalemate;Footnote ¹¹⁰

3. 3 as a justification for applying the vera causa criterion to a competing theory in order to reject that theory;Footnote ¹¹¹

4. 4 as grounds to counter Paley's formidable design argument about the vertebrate eye;

5. 5 as a partial substitute for an empirically based counter to Paley's design argument about the vertebrate eye;Footnote ¹¹²

6. 6 as a tacit premise in his argument about natural suffering and pain;

7. 7 as tacit assumptions in his famous homology argument, an area of study Darwin declared part of the ‘very soul’ of natural history.

I have also argued that Darwin drew upon theology not simply to argue for his theory, but to inform or undergird the theory (or key aspects of the theory), including:

1. 1 to support recourse to explanations involving only natural (or secondary) processes, causes and events;Footnote ¹¹³

2. 2 to help justify the trustworthiness of empirical data.Footnote ¹¹⁴

Finally, I have argued that a meta-level analysis of Darwin's theological statements reveals several tensions:

1. 1 imprecision in his argument from natural suffering,Footnote ¹¹⁵

2. 2 logical incoherence in his reply to Paley and use of Owen andFootnote ¹¹⁶

3. 3 the epistemic illegitimacy of the positiva theological claims in the Origin.Footnote ¹¹⁷

A number of scholars agree that Darwin used theology significantly in the Origin. As mentioned, John Brooke argues that Darwin borrowed from natural theology similar research problems, presuppositions, concepts, metaphors, patterns of argumentation and content for his theory.Footnote ¹¹⁸ In his careful study of Darwin's belief in evolutionary progress, Dov Ospovat argues that one of Darwin's justifications for progress in the face of natural suffering was ‘essentially the same’ as that of Malthus and Paley, namely ‘that the laws of nature were designed by a benevolent God’.Footnote ¹¹⁹ Abigail Lustig maintains that the Origin ‘was itself created in response to … the theological argument from design’ and can only be understood in light of its Paleyan theological heritage.Footnote ¹²⁰ Momme von Sydow holds that ‘three of the main influences on Darwin's biological theory’ are ‘Paley's belief in the divine design of nature; the conviction that God rules by laws which are eternal, universal and unchangeable; … [and] Malthus’ principle of population, partly presented as a theodicy’.Footnote ¹²¹ Strikingly, John Cornell and Robert Richards independently argue that the heart of Darwin's theory – natural selection – arises from Darwin's distinct theology.Footnote ¹²² Richards, for example, gives evidence that ‘Darwin created natural selection in the image of God’ so that ‘natural selection was more than a blind force of nature. It functioned as the surrogate creator operating according to divine command’.Footnote ¹²³ More generally, a number of historians argue that Darwin should not be understood as a man bent upon undermining theology so much as a radical reformer of natural theology.Footnote ¹²⁴

There is, in addition, Darwin's reductio use of theology. Recall that he frequently articulated special creationists’ own theology in order to empirically test it and find it wanting. Darwin repeatedly made these tests in a context of comparison to evolution, contending for the broad explanatory power of natural selection and common descent juxtaposed to the anaemic explanatory power of special creation. Reductio theology was, in short, essential to his comparative argument in the Origin.

As a brief aside, quite a few contemporary neo-Darwinists explicitly or implicitly employ some of the Origin's same theological claims and argument strategies.Footnote ¹²⁵ Although the present essay focuses only on the Origin, readers who doubt the presence of theology in contemporary discussions are encouraged to examine the cited references; they will find plenty of God-talk to go around.

One final question remains: even if theology in its various guises played an epistemic role in the Origin's case for evolution (and against special creation), how much of a role did it play, in particular, with respect to the roles of empirical evidence and naturalized (or secular) concepts, presuppositions, arguments, metaphors and the like? In short, how much did the Origin actually need God? While a full answer cannot be ventured here, two comments are in order. First, by way of clarification, this essay does not dispute that Darwin's theory in the Origin was naturalized in the crucial sense that it posited natural laws, entities and causes to explain biological change.Footnote ¹²⁶ Nor does it reject the centrality of Darwin's use of empirical evidence or non-theological concepts and claims to articulate, defend and apply his theory.

Second, and more importantly, teasing apart the fabric of Darwin's one long argument into ‘theological’, ‘naturalized’ and ‘empirical’ (and other) threads – and then assessing the individual epistemic importance of each – is an extremely complicated task, made more so by Thomas Kuhn's perceptive analysis of the interwoven nature of metaphysics, epistemology, methodology and empirical evidence in paradigms.Footnote ¹²⁷ If the scholars mentioned above are correct, then theology plays a large role in the concepts, assumptions, structure and defence of Darwin's argument and theory. But this essay defends a much more modest position, focusing on the epistemic role of positiva theology. In the Origin, this theology interfaces with empirical data and naturalized concepts and assumptions in complex ways, functioning on many different epistemic levels, from adjudicating background claims, to premises in arguments, to fundamental presuppositions. Despite this complexity, it seems reasonable to conclude that positiva theology was one of the many resources that Darwin drew upon, but neither the most frequent nor the most prominent resource. Positiva theology served as a handmaiden, faithfully assisting Darwin's central character (natural selection), and as an accomplice, working with a host of empirical data, logical inferences and naturalized concepts and claims to explain and defend evolution and to undermine special creation.

Handmaidens and accomplices are, of course, less alluring to historians than matriarchs and masterminds. But they are not unimportant. Positiva theology legitimized everything, from the trustworthiness of empirical data, to the famed homology argument, to Darwin's naturalized method. Despite its internal tensions, it informed both his ‘one long argument’ and his theory.

Contrary to conventional wisdom, the Origin did not so much separate science from theology as it articulated science from the vantage of semi-deism. Moreover, it proposed evolution by natural selection as an alternative to another theology-laden explanation, special creation. In the final analysis, the contrast in the Origin is not between theistic creationism and naturalistic evolution, but between theistic special creation and semi-deistic evolution – the latter with specific (and perhaps conflicted) notions of the existence, character, actions and obligations of God.