Thomas Aquinas holds, as Roman Catholic teaching still holds (2013, §375), that the first human beings, or our first parents, were created in a state or condition of “original justice,” wholly subject to God and so fully virtuous, as well as internally immune to bodily corruption, suffering, and natural death. ¹ It is only when our first parents—who I generically will refer to as “Adam”—sinned that they, along with human nature itself, were deprived of original justice. As a result, we human beings, having received our nature from Adam, are all born in a state of original sin and remain susceptible to experiencing intellectual, moral, and physical failure as a result. ²

In this article, I show how we intelligibly can locate “Aquinas's Adam” within evolutionary history. First, I briefly introduce Aquinas's Adam and describe his Fall along with its consequences for the human race. Then, I defend Aquinas's claim that Adam, while endowed with the gift or grace of original justice, was not susceptible to suffering or death, even though, according to evolutionary science, suffering and death existed well before the arrival of human beings within evolutionary history. Next, I argue against theologians like John Schneider who claim that Adam, given his evolutionary ancestry, was spiritually and morally frail or immature. Finally, I dispute the claim (advanced by Schneider and others like John Hick, working out of the Irenaean tradition) that Adam only could have fallen if he existed in an originally frail rather spiritually and morally exalted state.

In the end, then, I show the following. What Aquinas, arguing from the standpoint of Catholic Christian faith, says about Adam, original justice, and the Fall may not receive any direct support from evolutionary science. But there is real reason to think that the main features of his account remain fully compatible with it. As such, there is real reason to think that the revealed, theological truth that Aquinas professes (and the Catholic Church continues to profess) concerning Adam does not contradict but remains fully compatible with the truth about human origins as disclosed to us by evolutionary science. ³

Aquinas on Original Justice, the Fall, and Original Sin

For Aquinas, the state of original justice was a state of initial harmony and rectitude. Endowed with the gift or grace of original justice, Adam, as a rational being, possessing both intellect and will, was wholly subject to God. And it is because Adam's reason was wholly subject to God that his sensory appetitive powers, or the lower powers of the human soul, were wholly subject to reason (properly governed and moderated by reason). Accordingly, Adam, given his right relationship with God, was fully virtuous. Moreover, since his body was wholly subject to and perfected by his immaterial and incorruptible rational soul (which was itself wholly subject to God), Adam remained internally immune to bodily corruption and even death.

As Aquinas (2018) further understands it, original justice included sanctifying grace, which served as the “root” of original justice (ST I.100.1 ad 2). Adam was created in this state of grace, so that he could reach his distinctly supernatural end and highest happiness, or full participation in God's own life, without having to participate in sin or suffering. In fact, since original justice was “a special gift given by God to [human] nature as a whole” (2018, ST I.100.1), as “a principle of all human nature” (1995, QDM 4.1), God's original purpose was that all human beings be created in this state of grace, and possess original justice, as transmitted along with human nature itself to all of Adam's progeny, so that they, too, could attain beatitude in God without having to struggle with sin or experience any suffering.

However, following what he takes to be clear biblical testimony, Aquinas also holds that the divine purpose was thwarted by primal sin, itself the source of original sin. By freely and pridefully rebelling against God, Adam not only was deprived of his own “proper and personal good—namely, grace, and the due order of the parts of the soul; he was deprived as well of a good related to the common nature” ([1957] 1975, SCG 4.52). As a result, Adam's progeny, having received their nature from him, are born into a state of original sin—lacking the order of original justice—and suffer the consequences as a result. Because the body is no longer wholly subject to the soul per the ordering grace of original justice, we are naturally susceptible to bodily corruption and death, and suffer accordingly. Moreover, “all the powers of the soul remain in some way destitute of the proper ordering by which they are naturally ordered toward virtue” (2018, ST I‐II.85.3). ⁴ Like the fallen Adam, therefore, we are also beset by intellectual and moral deficiencies—or the “wounds” of ignorance, malice (“a certain proneness of the will toward evil” [2018, ST I‐II.85.3 ad 2]), concupiscence (or disordered desire), and weakness—which make living the spiritual and moral life difficult and even perilous. Aquinas (2018) also says that we can wound our natural inclination toward virtue even further by committing actual sins: “these are also the four wounds that result from other sins, insofar as through sin reason is clouded, especially in matters of action; the will becomes hardened with respect to the good; more difficulty accrues to acting well; and concupiscence becomes more feverish” (ST I‐II.85.3).

Thus, deprived of original justice, we fallen human beings still possess all of the requisite parts and powers that enable us to function as embodied, rational beings. But those parts and powers, bereft of the principle that rightly ordered them, can and do malfunction, and often do so drastically. In other words, deprived of original justice, we remain subject to serious and repeated intellectual, moral, and physical failure.

Aquinas's Adam, Suffering, and Death

Having briefly canvassed Aquinas's relevant views on original justice, the Fall, and original sin, let us now turn to the first major objection or concern regarding Aquinas's portrayal of the prelapsarian Adam: his purported immunity to suffering and death, which, along with disease and disaster, predate the arrival of human beings within evolutionary history. For example, Ian McFarland (2007) writes, “It is now beyond dispute that there was no point where human existence was characterized by immunity from death, absence of labour pains, or an ability to acquire food without toil…. The geological record makes it clear that natural disasters, disease, suffering, and death long antedate the emergence of the human species. It follows that such phenomena cannot be interpreted as the consequence of human sin” (143).

In response, I first need to make clear (and some may find this surprising) that Aquinas explicitly denies that no suffering and death occurred before the Fall. In particular, he takes the claim that predating animals did not engage in predative acts before the Fall to be “wholly unreasonable” (2018, ST I.96.1 ad 2). Aquinas (2018) writes, “For the nature of the animals was not changed through man's sin in such a way that certain animals, e.g., lions and falcons, for whom it is now natural to eat the flesh of other animals, lived off plants at that time…. Therefore, there would have been natural conflict among certain animals” (ST I.96.1 ad 2). Consequently, I think affirming Aquinas's claim that Adam did not suffer and would not have died, had he not sinned, does not require denying the claim that evolutionary history contains lots of suffering and death, or the more specific claim that Adam's evolutionary predecessors in the genus homo, and whatever other hominins among whom he lived, did not suffer and die.

Of course, affirming with Aquinas that Adam did not suffer and would not have died, had he remained sinless, also entails affirming with Aquinas that God specifically distinguished Adam from the rest of the animal creation on a distinctly metaphysical and not merely material or empirical level. According to Aquinas's metaphysics, human beings are form‐matter and specifically soul‐body composites, and while the body is naturally corruptible, the rational soul is not: since it is immaterial and subsistent as well as incorruptible, Aquinas thinks it must be produced in all human beings—beginning with Adam—directly by divine power alone (2018, ST I.90.2). Aquinas (2018) further claims that it was necessary for God, in creating Adam, to produce the body directly as well, since it had not previously been formed (ST I.91.2). However, taking on board what evolutionary science says about the gradual emergence of human beings on a material or empirical level, there is no reason why it is not possible to hold instead, in a genuinely Thomistic spirit, that God, at some point in evolutionary history, directly infused a rational soul along with original justice in already existing hominins—even two specific hominins capable of supporting a rational soul (per the teaching of the Catholic Church) ⁵ —from whom all human beings as rational animals, or soul‐body composites, descend. ⁶ Consequently, as chosen by God to be the first bearer of rational life, Adam alone, among the creatures with whom he lived, was able to avoid having to experience suffering and death in pursuing the distinctly supernatural end that God had assigned him.

What this also means is that had God not endowed Adam with original justice, he would have remained vulnerable to suffering and death like all members of the animal creation. Aquinas (2018) indeed recognizes that in one sense suffering and death are natural to human beings (minus the grace of original justice) because the human being qua soul‐body composite is naturally mortal (ST I‐II.85.6). Divine providence and goodness therefore ensured that whatever natural defects Adam would have been subject to by virtue of being a soul‐body composite would not impede his ability to attain his supernatural end. God supplied Adam the grace needed fully to order his soul to God, and his body to his soul, so that his body—which “was not incorruptible through any sort of vigor of immortality that existed within it” (2018, ST I.97.1)—in turn would be pervaded by the soul's life‐giving power (te Velde 2005, 162). This also entails, I think, that Adam's soul had the power to assist his body in maintaining itself over time, and thereby prevent damage from incurring at the molecular or cellular level, even if (per the “disposable‐soma” theory of aging) his body had to expend significant resources on processes such as growth and reproduction. ⁷ Accordingly, Adam (and his progeny, had they also been endowed with original justice) would not have succumbed to any age‐related ailments or undergone the sort of aging that terminates in death (senescence). As far as I can see, then, there is nothing incongruous in claiming that Adam's incorruptible soul, as initially graced by and subject to the ever‐living God, was capable of preserving his body from corruption and so prevented him from experiencing any suffering or death. Whatever one's position on the nature of the soul and human persons, it certainly seems metaphysically possible that this initial state of affairs obtained (or would have obtained, had Adam remained in a state of original justice).

Metaphysical worries aside, perhaps the real worry here is not that it would have been impossible for the prelapsarian Adam to remain immune to suffering and death (for how could we ever show this to be impossible?), but rather that it is very unlikely that the prelapsarian Adam remained entirely immune to suffering and the threat of death. One might argue that even granting that Adam possessed original justice, and so remained internally immune to suffering and death, he still would have inhabited an environment filled with real dangers to his overall well‐being. And so, the only way Adam realistically could avoid suffering and death is if he inhabited an Edenic paradise, completely walled off from any danger to his overall well‐being. Since we have strong reason to doubt that such a paradise actually existed, we have strong reason to doubt that Adam remained free from suffering and the threat of death.

However, I do not think that this claim is true. Notably, while Aquinas (2018) does hold that Adam inhabited a physical, paradisal place “fit for human habitation, in keeping with the state of initial immortality” (ST I.102.2), he does not also affirm that Adam, without any effort, could remain miraculously free from physical harm. “In the state of innocence,” he says, “man's body was able to persist without suffering injury from anything hard—partly because of man's own reason, through which he was able to avoid dangers, and partly because of God's providence, which protected him in such a way that nothing unexpected would happen to him by which he might be injured” (2018, ST I.97.2 ad 4). Accordingly, extending Aquinas's reasoning here, even if we grant that Adam did not inhabit an Edenic paradise, we do not need to deny that he had to protect himself from natural disasters or other animals (and perhaps other hominins), which would require that he exercise great intellectual ingenuity (albeit more practical than speculative) as well as moral and physical fortitude. Given his robust intellectual, moral, and physical constitution, successfully managing whatever dangers his natural environment posed to him would have been entirely possible, especially if he was further aided by the guiding and protective hand of divine providence. In fact, however challenging inhabiting and navigating Adam's natural environment might have been for him, it would not have been a source of real harm or conflict, and so suffering, for him. Whatever effort Adam expended in meeting the challenges his natural environment posed for him would not have compromised his virtuous pursuit of his assigned supernatural end. ⁸

It is also worth noting that it is entirely consonant with the Thomistic picture that I have offered that human beings always have been susceptible to pain, because pain, whether physical or mental, is part of the normal, healthy functioning of sentient animals, including human beings. Being susceptible to pain, however, is not the same thing as experiencing pain. By virtue of not experiencing sickness or disease, or any other substantial harm to his physical or mental well‐being, Adam would not have experienced pain, or at least, the sort of significant pain associated with sickness and disease, as well as other physical or mental infirmities. And so, I think, if Adam experienced any pain at all, it either would not have posed a significant threat to his overall well‐being, on a physical or mental level; or, it would have been the sort of minor, fleeting pain that proved useful to him in dealing with real or potential harms within his natural environment, so that he could inhabit and navigate it successfully.

Original Justice versus Original Frailty

Let us now turn to our second objection: Aquinas's spiritually and morally exalted Adam has no place in evolutionary history. John Schneider has argued that “Darwinian Adam,” as he calls him, who inhabited a “Darwinian World,” looks a lot different spiritually and morally than “Augustinian Adam”—and, we can add, “Aquinas's Adam”—since they share so much in common. At best, Darwinian Adam, says Schneider, was “a morally equivocal sort of person” (2012, 953), who had inherited his evolutionary ancestors’ proclivities to vice as well as virtue, at least of a more primitive, animalistic form, both rooted (it seems) in the biological disposition “to engage in our own genetic self‐interest and advantage” (2010, 202). It is much easier and better, then, Schneider says, taking into account common ancestry, along with recent animal behavior science, to find a place for “Irenaean Adam” in evolutionary history: a human being with the potential to develop spiritually and morally, but who was created spiritually and morally immature.

However, in response, I once again think it is possible to locate Aquinas's Adam in the “Darwinian World” that Schneider describes. Like us, Aquinas's Adam was a rational animal, and so would have inherited all of the traits from his evolutionary ancestors that aided them in the struggle to survive, including, most notably, the natural inclination to preserve our own being, which Aquinas (2018) claims we share with all substances (ST I‐II.94.2). But such an inclination, insofar as it stimulates the production and conservation of life, is good. Moreover, Adam's pursuit of sensual objectives like procuring food, water, and shelter—even if focused on his own survival, in an environment with limited resources—would have conformed with his overall aim of living in right relation with God and all other creatures among whom he lived.

Similarly, whatever his sociobiological heredity, Aquinas's Adam, as endowed with original justice, would not have experienced any tension or conflict between his reason and the pull of animalistic desire. Daniel Houck (2020), in developing a “new Thomist” view of the Fall, has suggested that this claim “stands in tension with evolutionary theory” (205), since evolutionary theory tells us that human beings did inherit and so would have struggled against, most notably, a tendency to aggressive violence. Consequently, Houck considers (though does not necessarily favor) an alternative scenario that he says is more in line with evolutionary theory: God afforded the first human beings the supernatural, sanctifying grace they needed freely to resist the temptation to commit violent actions even though they continued to struggle against that temptation. Although, he also admits that embracing this latter view may also entail affirming “that evil is built into creation” (2020, 205).

Unlike Houck (and Schneider for that matter), I do not see how denying that the prelapsarian Adam struggled against any inclination to engage in aggressive or violent behavior “stands in tension with evolutionary theory.” The only way this tension would arise is if one denied that Adam possessed such an inclination. But there is no need to deny this. We can affirm that Adam did inherit proclivities not just to aggression, but also promiscuous human mate choice, for example, since these proclivities were evolutionarily adaptive (at least in some ways) for his nonrational and subrational animal ancestors (Austriaco 2015, 658–63). However, since such proclivities would have impeded his ability as a rational animal not only to live the moral life successfully, but also fulfill his unique, spiritual vocation of attaining beatitude in God (Austriaco 2015, 658), God afforded him the gift or grace of original justice to ensure that he would not have to struggle against them. Consequently, on the Thomistic view I am defending, God afforded Adam as the first human being (and human nature itself) original justice not to alter or worse yet annul his physical nature but rather to ensure that it was properly ordered to his spiritual nature (that is, his soul), which itself was properly ordered to God. Put another way, in Thomistic terms, “since grace perfects nature and does not destroy it” (Aquinas 2018, ST I.1.8 ad 2), God endowed Adam with original justice in order to perfect or complete him as a being composed of a spiritual and physical nature, thereby enabling him to remain free from experiencing any internal disorder or disturbance that would have hindered his ability to recognize and pursue his overall good, in total accord with what right reason and divine law prescribe for human life.

What this also means is that the source or locus of sin within Adam was not his inherited animal nature. Rather, the source of sin within Adam, as a rational animal, who differed on a metaphysical level from all of his animal evolutionary ancestors, and whatever other hominins among whom he lived, was his will, so understood as a power of the rational soul. As a result, had God not afforded Adam the gift or grace of original justice, he would not have created him in a sinful state. Though, he would have left Adam in a severely disadvantaged and perhaps even perilous state, teetering on the edge between good and evil. And so, while strictly speaking God would not have acted unjustly or inconsistently with his perfect goodness if he did leave Adam in such a state—original justice was not owed to Adam as a rational being—he had every reason not to do so, given his ultimate aim of bringing Adam and his progeny into full and perfect union with himself.

We therefore intelligibly can locate Aquinas's Adam in the Darwinian World of evolutionary history in another, important respect. In a way, as a result of the Fall, Aquinas's Adam returned to a purely natural, spiritually and morally impoverished state and so would have experienced an “original fragility” of the sort that Schneider says Darwinian Adam experienced. On Aquinas's view, human nature was not fundamentally altered as a result of the Fall; rather, “nature was left to itself” (2018, ST I‐II.17.9 ad 3), shorn of the grace and help it once possessed. Consequently, none of Adam's moral powers, in themselves, which Adam possessed by virtue of being a rational being, were corrupted by the Fall. ⁹ Rather, once more, they were wounded as a result the Fall, given what they now lacked. Adam became subject to ignorance insofar as he lacked the robust spiritual and moral knowledge he once possessed; he became subject to malice insofar he lacked the robust will he once possessed to achieve what is good; he became subject to weakness and concupiscence insofar he lacked the robust ability he once possessed to harmonize his emotions or appetites with his reason (Shanley 2002, 101).

Moreover, since Adam's nature was wounded but not corrupted as a result of the Fall, Adam did not lose his natural inclination toward virtue, including (I would think) whatever rudimentary inclination toward virtue, including traits such as solidarity and cooperativeness, which he inherited from his evolutionary ancestors, and which were also part of his animal nature. Nor did he acquire a vicious tendency that directly disposed him to sin. Rather, he was inclined to sin given what he now lacked. Aquinas (2018) writes, “even though an inclination toward a disordered act follows from original sin, it follows indirectly and not directly, viz., through the removal of something that had prevented it, i.e., original justice, which had prevented the disordered movements—in the same way that an inclination toward disordered bodily movements follows indirectly from sickness” (ST I‐II.82.1 ad 3). And so, for example, insofar as the fallen Adam was inclined (to whatever degree) to engage in aggressive violence or infidelity, it is because he lacked the spiritual and moral health or vigor he once possessed, when his passions were fully responsive to his reason. As such, in his fallen state, he would have remained susceptible to and struggled against committing these and other sinful acts and so meet the demands imposed on him by his reason and divine law in living the spiritual and moral life.

Lacking original justice, Aquinas's fallen Adam, like Darwinian Adam, therefore faced the challenge (which he hitherto did not have to face) of living the spiritual and moral life successfully. Like a child, he became entirely dependent on divine grace (as we all now are) to heal his wounded nature, so that he could attain the supernatural end of union with God for which he was created.

Aquinas's Adam and the Free Fall from Grace

In the final section of this article, I address a third and final objection that is related to the second objection I just addressed: Aquinas's Adam could not have fallen while in a state of original justice because he would have lacked any psychological motivation to do so. 2007 puts the objection this way: “The basic and inevitable criticism is that the idea of an unqualifiedly good creature committing sin is self‐contradictory and unintelligible…. It is impossible to conceive of wholly good beings in a wholly good world becoming sinful” (62–63, 250). Similarly, articulating what he calls the “Paradisal Problem” (or, more recently, the problem of “Paradisiacal Motivation” (2020, 89–91)), Schneider (2012) asks, “How could anyone enjoying Beatific Personhood possibly become arrogant to the extent of defying God, self‐deceived to the extent of seeing this as good rather than completely evil, a better existential course and not the ruination of everything?” (962). Only a being who is “spiritually fragile in some key respect” could have fallen in this blatantly defiant and destructive way (2012, 962).

In large part, the objection is founded on a key misunderstanding, certainly of Aquinas's position on the kind of knowledge of God Adam possessed in the initial state of original justice. Aquinas recognizes that had Adam enjoyed what Schneider calls “Beatific Personhood,” then falling away from God would have been psychologically impossible for him. Since no one voluntarily turns away from happiness (which we all naturally desire) and the vision of God makes us perfectly happy, then “no one who sees God through his essence can voluntarily turn away from God, i.e., sin” (2018, ST I.94.1). Aquinas continues: “everyone who sees God through his essence is so stable in his love for God that he is unable to sin for all eternity” (2018, ST I.94.1). And so, had Adam enjoyed the beatific vision, he would have been so stable in his love for God that he would have been unable to sin for the entire duration of his earthly and heavenly life. Consequently, Aquinas (2018) claims that while Adam did possess a higher knowledge of God in the state of original justice than we currently possess (he knew God through his “intelligible effects” and not merely his “sensible effects” (ST I.94.1)), such knowledge still fell far short of the direct vision of God, and so it remained possible for Adam to sin even in his initial, privileged intellectual state.

Of course, we may still wonder what led Aquinas's Adam to sin, and particularly commit the sin of pride, since in the state of original justice he did enjoy a heightened knowledge of God and possessed a privileged relationship with God: he was wholly subject to God in his will and not just his intellect. Why would Adam, who was spiritually and morally upright, ever freely forsake God's goodness and turn to embrace his own inordinately?

Although I do not have the space here to answer this important question in full, I will provide at least the outline of a Thomistic (and more broadly Augustinian) answer. ¹⁰ Even in his spiritually and morally exalted state, Adam could and perhaps often did reflect on his own goodness as distinct from divine goodness. More than that, Adam recognized his goodness as something rightly to be desired, like all of the good things that God made. Of course, in his spiritually and morally exalted state, he also clearly recognized and held fast to the divine law or rule stipulating that he ought to subordinate his self‐love to his love of God: his highest good and highest happiness whom he ought to love above all other things (including, of course, himself). As long as Adam held onto this rule, and kept it squarely in mind, he would have been unable to will his own goodness in place of God's goodness, or completely apart from God's goodness, thereby sinning. However, were he to turn away from the rule (or, at least fail to keep the rule in mind) and then not turn back to it—which indeed would have been possible for him as a finite and mutable rational creature who did not yet enjoy the beatific vision—he would have possessed not only the psychological motivation (the love of his own goodness), but also the psychological room to will his own goodness completely apart from God's goodness in order to rest fully in his own goodness instead of God's goodness, thereby sinning.

This, then, is what I contend did in fact occur. At some point Adam abandoned his consideration of the all‐important rule subordinating his love of his own goodness to his love of divine goodness in order to dwell on his own goodness. Then, instead of freely turning back to the rule, he freely turned away from God as his highest good to (try to) find in himself his highest good, or (to try to) make himself the rule and measure of all things. In fact, we intelligibly can picture Adam acting in defiance of the rule by considering it and then abandoning that consideration in order to dwell on—and then choose for the sake of—his own, desired goodness as opposed to divine goodness, as he sought to find in himself his highest good, or make himself the rule and measure of all things. ¹¹ As 2017 puts it, Adam “sinned chiefly by coveting God's likeness as regards ‘knowledge of good and evil’…namely that by his own natural power he might decide what was good, and what was evil for him to do” (ST II‐II.163.2). ¹² In doing so, Adam fell, and fell hard—given his initial, lofty spiritual and moral state—thereby plunging himself (and us) into a sinful state: the state of original sin.

But why did Adam not seek out the rule so as to get it back in mind, thereby avoiding his catastrophic fall into sin? Aquinas says regarding sin in general, “there is no need to seek a cause of this non‐use of the aforesaid rule [of reason and divine law] because the liberty of the will itself, thanks to which it can act or not act, suffices for this” (1995, QDM 1.3). Therefore, it remained within Adam's power at the moment of choice to turn back toward the rule, which, in his privileged state, he very easily could (and should) have done, thereby guarding against sin. That he did not turn back toward it is ultimately due to the “the liberty of [his] will itself.” That is where explanation ends. In fact, trying further to explain Adam's sin only leads to a theological dead end: trying to find a positive reason for sin itself, when sin has no such reason, no ultimate justification. Sin contributes nothing on its own to the goodness of human life or the created order. Hence, in this sense, Adam had every reason not to sin, even though he was able to do so, and, tragically, for himself and his progeny, did freely do so.

Conclusion

Admittedly, none of what I have argued here suggests that it was likely that Aquinas's Adam would fall. I only have explained (in outline), in response to skeptics like Hick and Schneider, how it was possible for him to fall, and how I think his fall actually occurred, since, with Aquinas, I take it to be a datum of Christian faith or teaching that Adam not only did fall, but also fell from an originally just rather than fragile state. And while I certainly could say much more in defense of Aquinas's Adam on this count, I do think that I have provided real reason overall for thinking we can locate both the prelapsarian and postlapsarian Adam within evolutionary history. Although there are indeed no scientific reasons that directly support Thomistic and Catholic teaching about Adam, there is real reason for thinking that what evolutionary science in particular says about the material or empirical origins and nature of the first human beings is compatible with it. It is indeed possible to hold that what Aquinas says about Adam and what evolutionary science says about Adam are both true. ¹³