Thomas Aquinas and the Modern and Contemporary Debate on Evil

Abstract

This article aims to demonstrate that Thomas Aquinas's metaphysics of being, in which evil is considered a privation or lack of perfection introduced only by the creature against God's intention, is a remarkable starting point for solving the main problems involved in the modern and contemporary debate on the problem of evil. It also seeks to prove that Aquinas's position is neither reducible to an ‘optimistic theodicy’ –such as Leibniz's theodicy– nor to a ‘free will defence’.

Introduction

Is it possible to find in the work of Thomas Aquinas relevant contribution for the modern and contemporary debate on the problem of evil? My goal in this paper is to provide an answer to this question by comparing and contrasting Thomas Aquinas's account with the most representative positions of modern and contemporary thought on the issue. In the first section I will present the problem of evil in the terms in which it is frequently set out and I will show that the metaphysical coordinates for a proper understanding of the problem are those of the Western tradition of ‘theism’, within which we can frame Thomas Aquinas's position. In the second section I will define and explain what is meant by ‘Optimistic Theodicy’ as a specific kind of solution to the problem of evil and I will show why Aquinas's doctrine of evil does not fall under that characterisation. In the third section, I will define and explain what is meant by ‘Free Will Defence’ as another specific type of response to the problem and I will show why – contrary to what might seem to be the case – Thomas Aquinas's doctrine cannot be framed within this definition either. Finally, I will present Aquinas's definition of evil and both its metaphysical assumptions and implications, and presenting how this doctrine could offer relevant insights to the solution of the modern and contemporary debate on the problem of evil.

1. Theism and the ‘problem of evil’

By the ‘problem of evil’ one usually understands the speculative difficulty of reconciling the existence of an omnipotent, wise, and innocent God with the incontrovertible evidence of the abundant presence of evil events and actions in the world. The terms in which this problem has been traditionally framed were paradigmatically established in a famous ‘tetra-lemma’ attributed to Epicurus by Lactantius:^{1 2} whether God wants to eliminate evil and He cannot, whether He can and does not want to, whether He cannot and does not want to, whether He wants to and He can; if He wants to and cannot, then He is not omnipotent, which is unsuitable for God; if He can and does not want to, then He is not good, which is also inappropriate for God; if He cannot and does not want to, then He is neither omnipotent nor good, which means that He is not God; finally, if He can and wants to, there does not seem to be any intelligible explanation of the origin of evil.³

The problem of evil has always been and continues to be the atheist's strongest argument, given the fact that the existence of evil seems to be absolutely incompatible with the existence of an absolute Good, as Aquinas himself has shown.⁴ Boethius presented the problem as a dilemma: ‘If there is a God, where does evil come from? On the other hand, if there is no God, where does good come from?’⁵ Paradoxically, the second part of this dilemma shows that even if the existence of evil presents a speculative problem for those affirming the existence of God, the speculative problems that arise from the denial of God's existence are even more serious because one must then resign oneself to explaining the absolute origin of all reality and all rationality.

Hence, a rational response to the problem of evil presupposes the acceptance of all the terms that make the understanding of the problem as such possible. Thus, despite the apparent paradox, if one is to face the problem of evil philosophically – or, indeed, if one is to understand the existence of evil as a ‘problem’ – it is necessary to affirm both the existence of evil and the existence of an omnipotent, wise and good God. Even if one cannot clearly see the way in which these extremes can be reconciled, it will always be more rational to accept the mystery that this position implies, than the absurd conclusions to which the alternative positions lead. Indeed, all the doctrines that simplify the problem, by eliminating one of the above-mentioned terms, end up eliminating the possibility of giving a rational answer to the problem.

For example, some philosophical and theological schools have praised God's omnipotence and transcendence to the extent that they diminish God's goodness and human freedom, turning God into the arbitrary source of all good and evil. For example, Jakob Böhme's hermetic mysticism,⁶ Schelling's philosophy of freedom⁷ and, more recently, Luigi Pareyson's religious hermeneutics⁸ constitute philosophies that locate the origin of evil within the divine essence. However, in attributing the good-evil duality to the first principle of all things, these doctrines tend to fall into a Manichaean Gnosticism, which turns evil into a necessary and ineradicable element of reality. If such is the condition of evil, then evil loses its dramatic character – which is precisely why it shocks reason – and the very meaning of the problem disappears.

On the opposite extreme, some thinkers choose to minimize or eliminate divine omnipotence and transcendence. Thus, the so called ‘Process’⁹ and ‘Kenotic’ theologies¹⁰ divest God of His absolute attributes, including independence, impassibility and omnipotence. On this account, God wouldn't be capable of eliminating evil from the world and, in turn, He would not be a distant and transcendent spectator of evil, but rather an immanent principle of the historical process, a close companion of human suffering.¹¹ Now, this doctrine leads in a more direct way to unsolvable problems because, on the one hand, a God devoid of His transcendent attributes is no longer God and, on the other hand, because it turns evil into the necessary back side of the unfolding of history, and hence, being necessary, it destroys the problematic character of evil as such.

This brief summary of some of the positions that try to simplify the problem by means of eliminating one of its extremes shows that the problem of evil is the touchstone of all ontology. Depending on how this problem is confronted, one must accept certain metaphysical constants. Thus, a metaphysics that does not recognize evil as a real disorder contrary to the nature of things is prone to turn evil into an essential constituent of things and to identify it with the natural condition of finite being. It also tends to dissolve reality into an absolute immanent principle, which inevitably leads to the annulment of both the reality of evil and its dramatic character, as in Spinoza's and Hegel's paradigmatic immanentistic systems.

On the contrary, a metaphysics that concludes by accepting evil as a real and dramatic disorder – i.e., as something that could not and should not have been – tends to recognize the reality and consistency of finite beings. Accordingly, such beings receive their perfection within their essential constitutive limits, enabling them to attain and lose perfection. This metaphysics tends, at the same time, to accept the existence of an absolute transcendent Good that is the first cause of the perfection of finite beings. Thus, the question of the meaning of evil only acquires its real significance in the presence of an absolute transcendent Creator who is wise, good and omnipotent.

Thomas Aquinas’ doctrine of evil is framed within a philosophical tradition of ‘theism’ that shares the above mentioned criteria, together with other great thinkers of the Western World such as Saint Augustine, Boethius, Saint Anselm, Descartes, Malebranche, Leibniz and Antonio Rosmini, all of whom try to rationally establish the compatibility between the existence of evil and the existence of a wise, good, and omnipotent God. The answer to the problem of evil lies, for all of them, in the statement that God is not the cause of evil, but only ‘permits’ evil in order to achieve greater goods or to avoid greater evils that might follow from its non-permission. Quoting Saint Augustine, Aquinas states that ‘[s]ince God is the highest good, He would not allow any evil to exist in His works, unless His omnipotence and goodness were such as to bring good even out of evil’.¹²

However, the meaning of ‘to permit evil’ and how this permission should be conceived of has received many different explanations within the above-mentioned tradition, depending on the different metaphysical concepts adopted in the respective technical accounts of this point. Among the many doctrines elaborated with the aim of giving a rational response to the problem of evil, two of them deserve special attention, given their influence and relevance in modern and contemporary thought. I will refer to these two accounts as ‘Optimistic Theodicies’ and the theories of ‘Free Will Defence’.

2. Thomas Aquinas and the ‘Optimistic Theodicies’

The term ‘Theodicy’ is a compound from the Greek words theós (God) and diké (justice). Etymologically it means a ‘justification of God’. Coined by Leibniz, the term appeared for the first time in some of his manuscripts during the 1690s¹³ and was officially published in his Essays of Theodicy (Amsterdam, 1710).¹⁴ According to Leibniz, God is free in his act of creation, meaning that He has infinitely possible ways of creating the world, represented in the divine intellect from which He chooses only one.¹⁵ Assuming the universal character of the principle of sufficient reason and the absolute goodness and wisdom of God, Leibniz states that it is necessary to conclude that God must act in the best possible way, not in virtue of an absolute metaphysical necessity, but by means of a ‘moral’ necessity that depends on God's first free decree of choosing the best.¹⁶ Hence, the world that was actually created, with all the evil contained in it, must be the best of all possible worlds, counting those that do not contain any evil in their state of possibility.¹⁷ Therefore, the present world contains the lowest proportion of evil, which serves as a mean, or, at least, as a sine qua non condition for obtaining the greatest amount of perfection in the universe.¹⁸ In this context, that God ‘permits’ evil implies that He is its indirect or per accidens cause.¹⁹ This is true for ‘metaphysical evil’ (evil of nature), as well as for ‘physical evil’ (suffering) and ‘moral evil’ (sin).²⁰

This paradigmatic scheme of ‘theodicy’ had many followers within the rationalist doctrine of ‘metaphysical optimism’, which suggested a kind of justification of divine behaviour implying at the same time the justification of evil itself. In his novel, Candide or the Optimism (1759), Voltaire aims to criticise this type of doctrine; Kant too takes up this criticism in his brief manuscript, On the Miscarriage of All Philosophical Trials in Theodicy (1791). The term ‘theodicy’ is used nowadays in a broad sense to refer to every philosophical doctrine that is not merely a ‘defence’ – i.e. that does not seek only to establish the compatibility between the existence of God and the existence of evil –, but tries to give a ‘positive’ reason for God's permission of evil.²¹ Nevertheless, I will use the term here in its original sense, to refer to the specific ‘optimistic’ doctrines that share the following features:

1. 1. Holism: The perfection of the created universe taken as a whole is the ultimate reason for the permission of evil.

2. 2. Consequentialism: The justification of the existence of evil is based on the fact that it is a means, or at least a sine qua non condition that can be instrumental in achieving the greatest perfection of the universe.²²

3. 3. Optimism: There is a direct connection between the optimal character of God's work – i.e. between the proper proportion and amount of worldly goods and evils – and the goodness or ‘moral perfection’ of God.

Even though contemporary philosophers do not normally defend these features explicitly, they sometimes do appear implicitly in certain approaches to the problem of evil. It is, then, worth comparing this doctrine with Aquinas's doctrine, which has frequently been characterized as a kind of theodicy.²³ Leibniz himself cites Aquinas in some key passages, endorsing his alleged doctrine on the ultimate reason for God's permission of evil.²⁴ I shall approach this analysis through the three defining features of ‘optimistic theodicy’.

Is Thomas Aquinas's doctrine a ‘holistic’ one? It is undeniable that in some texts, following neo-Platonic principles, Aquinas explicitly links the permission of evil with the total perfection of the universe. Indeed, as Aquinas says, the perfection or ‘form’ that God seeks to express in His creatures is the order of the universe.²⁵ He thus does what is best for the whole and not just for each of its parts, unless it is necessary for the perfection of the whole.²⁶ However, perfect goodness in created things requires inequality²⁷ because the perfection of the universe calls for the fulfilment of all the degrees of being and goodness.²⁸

Now, Aquinas continues, there is a degree of goodness that, by its own nature, cannot fall from its proper good, but there are some other degrees of goodness that are capable, because of their own nature, of falling from their good. Therefore, both degrees are necessary for the greatest perfection of the universe.²⁹ Nevertheless, since divine providence does not seek to destroy the nature of things, but rather to preserve them, He sometimes permits that the things that by their own nature can fall, do effectively fall from their own good.³⁰ Aquinas concludes:

Hence, many good things would be taken away if God permitted no evil to exist; for fire would not be generated if air was not corrupted, nor would the life of a lion be preserved unless the ass was killed. Neither would avenging justice nor the patience of a sufferer be praised if there were no injustice.³¹

In conclusion, for Aquinas, evil is undoubtedly permitted in an antecedent and general way for the perfection of the universe as a whole; i.e. for the perfection of the universe, the Creator possesses an indifferent openness to the possibility of the existence of the defects in His creatures.³²

Does this fact mean that for Thomas Aquinas evil is a ‘means’ or a sine qua non condition for obtaining certain goods? The answer is absolutely not. Aquinas himself clarifies that the fact that some goods that otherwise would not exist are brought about by the permission of evil does not mean that evil can per se perfect the universe.³³ Indeed, a thing can only confer some perfection to another thing if it is a constituent part of it, or if it is something that causes some perfection in it.³⁴ Now, since evil is neither a substantial nor an accidental reality, but rather a privation, it cannot be a constitutive part of the universe, neither can it be per se the cause of any good.³⁵ Evil can only cause some perfection in the universe per accidens, insofar as that evil is linked to something that contributes to the perfection of the universe.³⁶

Even if this last principle is universally valid for every evil, however, it must be applied in an analogical way, according to the different kinds of evil. There are some evils without which the world would be less perfect, as is the case of evils from which a greater perfection can be obtained than the perfection they remove. For example, the corruption of the elements from which a mixed corporal substance is generated results in the form of the latter being more perfect than that of the former.³⁷ This is the general case concerning ‘evils of nature’, i.e. the evils affecting the qualities and actions of the physical agents that are natural consequences of both their reciprocal causal cross-linking and their matter-form composition. So too is this the case concerning ‘moral evils of punishment’, i.e. the privations opposed to the will of rational creatures that they undergo as a consequence of a previous fault. In both cases, that God permits those evils means that He is its indirect or per accidens cause, because they are the result of the expression of the natural form of the universe³⁸ or the result of the restoration of justice in it.³⁹

Aquinas explains, however, that there is another kind of evil without which the universe could have been more perfect. This kind of evil deprives certain individuals of a greater perfection than that which other individuals obtain from it. This is the case of ‘moral evils of fault’, i.e. the voluntary actions committed by a rational creature that are not ordered towards his natural end. This is, according to Aquinas, evil in its most precise sense because it is directly opposed to the infinite Good.⁴⁰ The perfection obtained by means of the permission of this kind of evil could be achieved without it; for example, to acquire patience and achieve salvation, suffering persecution is not strictly necessary.⁴¹ In conclusion,

[…] the whole humankind would have been better, if no man have sinned; since even if one's salvation were directly caused from other's fault, nevertheless the former could have reached salvation without this fault; however, neither these nor those evils contribute per se to the perfection of the universe, because they are not causes of perfection, but occasions.⁴²

Hence, the evil of fault can be an ‘occasion’ for obtaining certain goods,⁴³ insofar as it occurs within circumstances that favour the obtaining of such goods.⁴⁴ As Aquinas explains, certain goods or perfections are materially related to evil, insofar as evil provides the occasion for achieving them, as is the case of the man who obtains patience and virtue under persecution.⁴⁵ Nevertheless, no subsequent good in particular is necessarily linked to any antecedent evil of fault, so that there are no other ways of obtaining it. That is why Aquinas states that evil of fault can be neither directly nor indirectly caused by God⁴⁶ and its permission is in no way the necessary consequence of the goods God seeks to achieve.

That God permits the evil of fault means that He causes, moves, and preserves the deficient act of a created free will. Nevertheless, the creature is the only cause – even the primary cause⁴⁷ – of any kind of defect in its action, creating an obstacle to divine causality.⁴⁸ The moral evil of fault is a necessary possibility of a created free-will, but its effective actualisation is absolutely contingent. This is far from a consequentialist approach, in which moral evil is instrumental for the achievement of a greater good.

Concerning metaphysical optimism, it is important to make some relevant clarifications. Thomas Aquinas explicitly asserts the absolute perfection of divine action, stating that God could not act better than He does. Nevertheless, this statement must be correctly understood. If ‘better’ refers to the mode of divine action, it is obvious that God cannot act better than He does, since His act of creation actively considered is an immanent act identical to the perfection of His essential wisdom and goodness, which does not allow for any comparison.⁴⁹ On the contrary, if ‘better’ refers to the perfection of the created effect then the perfection of God's action is not exhausted by any of His effects, given that every creature is perfectible. In this sense, God can make things better than He does, absolutely speaking.⁵⁰

Hence, there is no such a thing as the ‘best possible world’ because there is no one suitable way in which divine wisdom and goodness are manifested. The perfection of divine action cannot be measured by any actual or possible created effect, since the aim in virtue of which He acts ad extra – i.e. His own glory – would be infallibly reached in any case and with any type of creature, regardless of the way it might act. Of course, these assertions can only be understood within a metaphysical approach in which God's act of creation is not reduced to a mere actualisation of a complete world, already unfolded in the realm of pure possibilities or – using contemporary terminology – to the mere instantiation of certain ‘states of affairs’. For Aquinas, God creates by communicating the participated act of being to certain subjects with their own operative capacities⁵¹ and ordinarily preserves and respects their natural ways of acting, whether necessary or contingent, fallible or infallible.⁵²

In this sense, despite the general rejection of the rationalist theodicy by present day philosophy and theology, some of its fundamental assumptions still persist. Indeed, many of the objections to divine goodness based on the quantity and quality of the evil present in the universe—⁵³ and many of the responses to these kinds of arguments —rest upon the consequentialist supposition that, in order to defend the perfection of divine action, God cannot fail. This thus necessitates a balance in which the quantity and quality of evils do not overcome the amount of good in the universe; for example, the number of souls damned could not be more than the number saved. In this sense, I agree with Peter Van Inwagen's suggestion that the amount of evil that God permits must be undetermined since there is no ‘minimum quantity of evil’ through which God could reach His ends.⁵⁴ Hence, there is no quantity or proportion of evil in the world that could serve as a definitive objection to divine innocence.

This kind of objection seems to neglect the possibility that God could have decided to take a real risk in creating fallible rational beings, opening the possibility of the total failure for every one of them simply for the sake of the great value that the free attainment of good has in itself. This decision, however, does not mean that God's action was in any way imperfect. This consideration can be made independently of the degree of certainty concerning the possible over-compensation that we can expect from an omnipotent, wise and good God. This is, indeed, one of the main premises of the ‘free will defence’.

3. Thomas Aquinas and the ‘free will defence’

Over the past 40 years, a renewed confidence in the possibilities of building a rational theology that responds to the objections based on evil has emerged, especially in the context of analytic philosophy. From this perspective, the most frequently employed strategy is the so-called ‘free will defence’.⁵⁵ It has been supported with different nuances by authors like Alvin Plantinga,⁵⁶ Richard Swinburne⁵⁷ and Peter Van Inwagen, among many others. This strategy has been extremely successful as a response to the so called ‘logical problem of evil’, showing that there is no logical incompatibility between the existence of God – with all His traditional attributes – and the existence of evil.⁵⁸ Without dealing with the particular details of each proposal, this strategy could be characterised by some more or less common assertions:

1. 1) God permits all the evil that the free will of the creature – by its own nature – makes possible because of the great good that the existence of a free will allows.⁵⁹ That the creature's free will is a good of great value is made evident by the fact that it is the necessary condition not only for responsible moral behaviour,⁶⁰ but also for an amicable relationship among the created and with their Creator.⁶¹

2. 2) A ‘morally relevant’ free will implies, by its nature, that it contains a self-determining power and thus the possibility to choose between good and evil options. Therefore, God could not have created free beings without opening the possibility of moral evil.⁶²

3. 3) Some free will defenders go even further, stating that it would be impossible – i.e. contradictory – for God to create a world with free will and without evil. According to Plantinga, God cannot actualise a world that explicitly allows or prohibits some action; indeed, God can only actualise in a strong sense that which He can ‘cause’ to be actual.⁶³ Now, ‘if God brings it about that I refrain from A, then I don't freely refrain from A’,⁶⁴ because free will presupposes independence from causal laws and antecedent determining conditions.⁶⁵ That is why Plantinga rejects what he considers ‘Leibniz's Lapse’, i.e. the assertion that God could create any possible world⁶⁶ and why the free will defenders generally state – against Mackie's classical compatibilist objection –⁶⁷ that God could not create a world in which men always choose the good,⁶⁸ i.e. a world that only contains moral good and not moral evil. According to Plantinga, this statement is at the ‘heart of the free will defence’.⁶⁹

4. 4) Free will is not just the condition of possibility of the evils produced by it (moral evils), but also of every physical evil that creatures suffer. Given the special difficulty of ‘natural evils’ that are not the product of man's actions, many different hypotheses have been suggested on this matter. Thus, Plantinga has attributed natural evils to the devil's free will.⁷⁰ Swinburne has appealed to ‘the necessity of knowledge’ argument, which asserts that the possibility of natural evil is connatural to a regularly ruled world that allows men to make the necessary inductions required for a positive exercise of free will.⁷¹ Finally, Van Inwagen suggested a conjectural story about the ‘state of original justice’ and the fall of the first man as the cause of mankind's mismatch with nature.⁷²

Many authors have emphasised the similarity and the continuity between the arguments based on free will defence and the classical doctrines of Augustine, Anselm and, of course, Thomas Aquinas.⁷³ As in the previous section, it is worth analysing this issue in detail, specifically asking whether the above described characterisation fits with Aquinas's approach to the problem of evil.

As stated previously, in order to fulfil the degrees of perfection in the universe, God creates that which can fall from its own good, as is the case of free creatures.⁷⁴ This means that the good that these free creatures represents for the perfection of the universe is per se a greater good than the price paid for it. For Aquinas, the good of every rational creature is more valuable than the whole material world.⁷⁵ The possibility of ‘glory’ — i.e. the possibility of freely entering into an amicable relationship with God and seeing God's essence ‘face to face’ — is worth the possibility of sin and even of eternal damnation.⁷⁶ On this point, Aquinas's doctrine is not only perfectly concurrent with that of the free will defenders, but is also one of their most obvious historical sources.

It is also true that for Aquinas the creature's free will is naturally fallible or ‘flexible’ towards evil. Aquinas clearly states that ‘any rational creature, be it angel or man, considered in its own nature, can sin’.⁷⁷ Jacques Maritain has explained this idea, stating that a naturally infallible creature is a ‘squared circle’.⁷⁸ Nevertheless, it is necessary to add an important qualification to these assertions. As Josef Pieper has pointed out,⁷⁹ the possibility of choosing evil is for Aquinas a ‘sign’ of free will,⁸⁰ but it is not a constituent part of it: ‘It does not belong to the essence of free will to be able to decide for evil’.⁸¹ God, being free, cannot choose evil,⁸² and neither can the blessed lose their free will when they are already confirmed in the good.⁸³ This means that for Thomas Aquinas the impossibility of choosing evil is not a limitation or an annulment of free will, but its ultimate consummation and perfection.⁸⁴

Following Augustine, Aquinas states that the creature's free will is not fallible insofar as it is a free will, but insofar as it comes ‘from nothing’,⁸⁵ i.e. because it is a ‘created’ free will. The possibility of choosing evil is not inherent to free will as such, but it is inherent to a finite free will. Moreover, even if it must not be said that the creature's limitation is a ‘metaphysical evil’, it can be said that the creature's limitation is the metaphysical root of the possibility of every kind of evil. For Aquinas, this statement is based on the metaphysical composition of act (being) and potency (essence) theses, characteristic of every creature as such.⁸⁶ The metaphysical composition of being and essence entails the non-identity between the created subject and the perfection it receives.⁸⁷ This non-identity makes it possible for the creature to loose or to acquire perfection through its own actions.⁸⁸ Thus, this metaphysical composition is at the same time the root of the creature's perfectible and fallible character.

Concerning the relation between divine causality and created free will, it must be said that for Aquinas it is not only possible for God to ‘cause’ a creature to act freely, but that such is precisely the case in every single good action the creature performs. This thesis is the natural consequence of Aquinas's metaphysics of creation, which implies the total and radical dependence of every created being with regards to divine causality. This comprehensive causality does not exclude the creature's free actions since every secondary cause acts ‘by virtue of the first cause’.⁸⁹ God radically moves the creature's free will as its first cause, not only insofar as He preserves it in being, but even applying the created will to its own act.⁹⁰

This does not mean, however, that Aquinas's doctrine is a sort of ‘compatibilism’ that accepts the coexistence of free will and determinism in our actions. In fact, his position is based on principles that are beyond the whole debate between compatibilism and libertarianism in the terms in which this debate is frequently set, i.e. as a false dichotomy between causality (understood in a deterministic way) and free will. In order to accurately understand Aquinas's perspective it is worth considering some features of the notion of causality applied to God's action toward His creatures.

In the first place, God's causal action ad extra is always creative causality, which does not presuppose any subject.⁹¹ This means that God does not simply allow an already existing free will to act (libertarianism) or determine it towards any one option or the opposite (compatibilism), as if it were a pre-existing thing. On the contrary, God's creative action constitutes its own term in its participated being and with its participated acts. Hence, divine causality not only does not negate created free will, but it is its ultimate foundation, given that the free creature is all the more influenced by divine causality the more it acts with its own causal power.⁹²

Secondly, Aquinas's concept of causality does not imply the univocal determination of the effects from their antecedent conditions. It merely implies the actual dependence of what we call ‘effect’ with regards to a principle from which it receives its being, which is called ‘cause’.⁹³ The actual dependence of the creature's free actions upon God's creative causality does not imply that those actions are not contingent. On the contrary, divine causality is precisely the root of contingency, insofar as God wanted certain things to happen contingently and thus adjusted the contingent causes, proportioned to their nature.⁹⁴

One could even say with Maritain that preserving the creature from its natural fallibility – without making it properly ‘impeccable’ – falls under the scope of divine omnipotence, by ‘infallibly’ moving the created free will to the good in an extraordinary and supernatural way without destroying its nature.⁹⁵ Indeed, if this possibility is to be accepted, it does not follow that if God does not always act in that way, one ought to object to His goodness. In order to exonerate God from being responsible for evil, it is sufficient to say that He ordinarily moves the created free will in the fallible way connatural to it or, as Maritain says, with ‘breakable motions’ that are sufficient for good action.⁹⁶ In this sense, Mackie and the free will defenders make the same false assumption in asserting that if God could create men in such a way that they always freely choose the good, He should do so.

Finally, since they do not get the ultimate root of the possibility of evil right – i.e. the metaphysical composition of being and essence – free will defenders are forced to appeal to some ad hoc arguments, in order to link the possibility of every physical evil with free will. For Aquinas, there is of course a link between suffering and the evil of nature on the one hand, and free will on the other hand, since those kinds of evils did not affect man in his state of original justice, but they currently do as a consequence of original sin.⁹⁷ However, this connection cannot be the object of a mere philosophical conclusion, but is a matter of faith. Even though many of the free will arguments concerning this matter are presented as probable hypotheses without a demonstrative aim, they fall into a certain categorical error because they try to solve a question that belongs to revealed theology in an exclusively philosophical manner. In that sense, P. A. McDonald Jr. has recently shown that Aquinas's essential openness to revealed theology in his metaphysics can provide a much more solid foundation for free will arguments by legitimizing the rational use of revealed truths for solving philosophical problems.⁹⁸

From a mere philosophical perspective, it must be said that both suffering and the evil of nature in general have their root in the naturally corruptible character of every physical being. According to Aquinas, every natural or physical being, given its matter-form composition, has the possibility of not being, i.e. every being can lose its form or substantial perfection, whether by being corrupted or by losing its accidental perfection as a result of the causal action of other physical substances.⁹⁹ Hence, these kinds of evils are permitted, generally speaking, because of the principle of the convenience of the degrees of being, given that God could not have created the material world – the lowest degree – without producing per accidens the evil entailed by such corruption.¹⁰⁰ This conclusion does not prevent that, from a theological perspective, some of these evils can also be considered evils of pain, insofar as they affect men as a consequence of sin.

4. Thomas Aquinas on evil as ‘privation’ and its metaphysical implications

Since Aquinas's doctrine does not fit into any of the more widespread modern and contemporary solutions to the problem of evil, what can be positively expected from it? In a recent paper, Sam Newlands has pointed out that one of the most notable failings of the current approaches to the problem of evil lies in the lack of a clear definition of ‘evil’, showing that, after early modern philosophers harshly criticised the classical Augustinian definition of evil as privatio boni, theist authors have offered no alternative definition.¹⁰¹ Newlands even suggests that the definition of evil as privatio should be revisited, given that no alternative definition can be formulated without falling into Manicheism, i.e. turning evil into a positive ontological reality.¹⁰²

In this sense, I think that Aquinas's definition of evil is his most important contribution to this debate. Thomas Aquinas does not simply repeat Augustine's definition,¹⁰³ but develops it further, grounding it on his solid and original metaphysics of being. Thus, Aquinas's definition of evil as privation has certain implications that allow it not only to overcome the criticism to which other definitions have been subject, but also to understand the whole problem of evil from a different perspective. A few brief considerations will help to see the importance of Aquinas's contribution:

1) The most frequent criticisms against the definition of evil as privation are based on the accusation that such a definition reduces evil to mere appearance without any reality,¹⁰⁴ which clearly does not account for the repugnance that the world's abundant presence of evil produces.¹⁰⁵ However, without delving too deeply into these objections, it must be said that this kind of criticism suffers in general from a superficial comprehension of what the concept of privation means. This concept is frequently mistaken for a mere lack of perfection. This misunderstanding is clear, for example, in Swinburne's erroneous identification of the classical definition of evil as privation with the Hegelian doctrine of finitude as intrinsically evil.¹⁰⁶

On the contrary, Aquinas does not think that every lack of perfection can be considered evil, but that it is necessary to establish a distinction between the ‘privative’ and the mere ‘negative’ absence of perfection. Thus, the limits that constitute a thing in its own nature only delineate a mere negative absence of perfection. Every lack of a perfection that does not belong to the nature of a thing is a merely negative absence, while every lack of perfection that deprives a thing of a good that it should have by virtue of its nature is referred to as ‘privative’.¹⁰⁷ Hence, the lack of wings is not an evil for man, given that the power of flight is not proper to human nature, while blindness constitutes an evil for man precisely because nature should provide him with sight. Evil is not just a negation, i.e. the absence of any good or perfection, but it is, properly speaking, the privation of a proper good, i.e. the absence of a perfection that belongs to the nature of a thing.¹⁰⁸

Hence, to say that evil is privation does not mean to deny its reality absolutely, but merely means to affirm that it alone lacks form or nature and that it is not capable of existing on its own: it can only exist as a ‘mutilation’ in the being of creatures. Evil subsists in and acts through those goods that it corrupts or deprives and its reality and efficiency comes from those goods.¹⁰⁹ That is why evil is worse and manifests itself more harshly the greater the goods that it corrupts are. Its dramatic character lies precisely in its ‘parasitic’ and ‘corrosive’ existence.

2) This doctrine can only be properly understood within the context of a metaphysics of participation in the act of being, for which every created being results from the composition of two co-principles: 1. the perfection received from God, i.e. the act of being, and 2. the subject that receives it, also referred to as the finite essence. There can only be genuine privation or lack of perfection where there is a metaphysical composition. In order for a given subject to be deprived of the perfection proper to it, said subject must be different from its perfection.¹¹⁰ Insofar as the creature is not identical with the act of being it possesses, neither is its essence identical to its operative powers and actions.¹¹¹ That the creature's essence and operations are not identical makes for an ontologically open being, capable of obtaining its own perfection – according to the limits marked by its nature – through its actions. For this same reason, the creature can lose being or perfection, introducing defects or faults in its actions and derailing them from the ends proper to its nature.

3) Given this ontological assumption, the existence of privative evil, insofar as it presupposes the non-identity between the essence and the act of being, is an unequivocal sign that the creature's act of being is participated and, therefore, caused. Hence, the recognition of the privative character of evil is an implicit recognition of the existence of God as the un-participated source of every participated being, following Aquinas's famous fourth way.¹¹² That is why, confronted with the dilemma posed by Boethius – si Deus est, quidem unde mala? Unde bona si Deus non est – Aquinas replies that the existence of evil does not imply the denial of God; on the contrary, it is a confirmation of His existence: “If there is evil, there is a God. For there would be no evil, if the order of good were removed, the privation of which is evil: and there would be no such order, if there were no God.”¹¹³ The starting point of the atheist's objection loses all meaning, given that without the existence of God – absolute Good – there can be no good finite being capable of falling from its natural order, in which case evil ceases to be evil. This consideration suggests a total reversal of the terms in which the problem of evil is frequently set. Indeed, if the definition of evil is firmly established from the beginning, even before dealing with arguments concerning the ‘logical’ or the ‘evidential’ problem of evil, the burden of proof is on the atheist to explain the existence of evil without appealing to the existence of a first principle in the order of good.

4) The definition of evil cannot be separated from the question of its causality. Indeed, the definition of evil as privation makes possible a better understanding of the problem of its divine permission. As Maritain has rightly pointed out, the principle of the absolute asymmetry between ‘the line of being’ and ‘good’, and ‘the line of non-being’ and ‘evil’, must be pushed to its ultimate conclusions. In the line of being or good, God is the first cause of the perfection we find in creatures, on both the substantial and the operative levels. Also in the line of being, creatures are secondary causes of their actions, i.e. real and proper causes on their own level. On the contrary, in the line of evil or non-being, things happen in a different way, given that we are in the order of ‘deficient’ causality. Thus, if we consider the case of suffering and evils of nature in general, it cannot be said that they are directly caused by God, since He is only the cause of being; nevertheless, it can be said that He indirectly or per accidens causes them, as has been shown above.

5) However, God cannot be the cause of moral evil of fault, ‘neither directly nor indirectly’.¹¹⁴ Moral evil of fault, evil in its absolute sense, is radically opposed to the absolute Good and to His will, manifested in the natural inclinations of the creature. What is, then, the cause of moral evil of fault? Every created free will has to adapt itself to a rule of action – the moral law – different from the will itself. That is why created free will, at the moment it chooses, has the power to consider or not consider the rule that should inform its action. Hence, the free ‘non-consideration of the moral law’ causes the defect in the act of choice and then turns that action into an evil of fault. Now, this ‘non-consideration’ is not a privation in itself, but rather a mere negation, because continuous attention to moral law is not a required to the rational creature. Rather, it is only so at the moment in which the creature chooses. As a negation, this non-consideration is not properly speaking an act, i.e. something positive, but a defect freely introduced by the creature in its act of choosing.¹¹⁵ Therefore, God's causality is not involved in such non-consideration; rather, He only preserves in being the act with the defect introduced exclusively by created free will, which is self-sufficient enough to be the first cause of evil of fault.¹¹⁶ Indeed, created free will has the first initiative in the line of evil or non-being and, in some sense, has the capacity to frustrate God's antecedent will.¹¹⁷

Conclusion

My aim in this paper has not been to make a complete exposition of Thomas Aquinas's doctrine of evil,¹¹⁸ nor has it been to deal with all the speculative problems this doctrine can entail. I have only attempted to show how Aquinas's doctrine of evil is not easily reducible to any of the most frequent responses to the problem posed by modern and contemporary philosophers. It can be said that, strictly speaking, Thomas Aquinas did not propose a solution to the problem of evil in the modern and contemporary sense. Nevertheless, in his work we find a solid metaphysics of being, with which we can certainly uncover principles for a proper understanding of the reality of evil. From Aquinas's perspective, evil is always a real absence, an ontological impoverishment and a genuine loss of perfection for the creature, which it alone introduces against God's original intention. Hence, the fact that God permits evil, by respecting the natural fallibility of His creatures, does not constitute a real objection to His wisdom, goodness and omnipotence.