Critically assess Thomas Aquinas’ approach to the problem of evil

Critically assess Thomas Aquinas’ approach to the problem of evil


St Thomas Aquinas was one of the most influential theologians to date and his influence on the Catholic faith and understanding of ethics is both vast and undeniable. As a theologian he took great influence from the work of St. Augustine who in turn took influence from the Greek philosopher Aristotle. To understand Aquinas’ approach to the problem of evil it is important to first examine the influence he took St. Augustine. I will also look at another approach to the problem of evil given by the modern British theologian John Hick. I will see if this accounts for anything which Aquinas’ account does not.

St. Augustine’s work on the problem of evil came as a reaction to the Manicheans’ who believed in a type of ‘cosmic dualism’. Their belief was that there were two opposed forces in the universe; the force of good and the force of evil. The force of evil was responsible for all evil that occurred in the world; be it the death of a relative or a very poor yield of crops. These forces, according to the Manicheans’, were in a constant cosmic battle against each other. This view of the forces of good and evil can be seen in modern literature and film and a good example of this is the book Lord of the rings. In the lord of the rings Frodo and the other members of fellowship can be seen to represent the force of good and Sauron and his dark army can be seen to represent the forces of evil. The Manicheans supported their dualist claim that there were both evil and good forces in the world through quotations found in the book of revelations which state that St Michael and some angels went into battle with the devil and his angels (the similarity between this and the battles in the lord of the rings is very apparent).

St Augustine did not accept the Manicheans account as he did not believe it was a Christian position; believing that there was a separate force of evil was not a defensible position for a devout Christian. Many religions, including Christianity, Judaism and Islam, state that there is only one God and that one God created the universe and everything within it. From this we can take the position that there can be absolutely no independent or separate power of evil due to the fact that everything that exists was created by an all powerful and completely good God. But how then does one account for evil being present in some form within the worldSurely one must either accept that evil does not exist at all or that the God of which we speak is not utterly good or that god is not omnipotent. Cleverly St. Augustine managed to avoid this problem by introducing some of the philosophy of Aristotle; namely that of his work on absence.

Aristotle believed that many things we could view as being a negative force or thing could actually be explained in terms of the absence of something good. Where we may view sickness as being the introduction of a virus or a parasite into somebody’s previously healthy body Aristotle would have viewed it as a ‘lack of health’. So where health is not present there is sickness. Another good example is ‘where there is darkness there is an absence of light’. So, for Aristotle, many negative things can be seen as an absence of something positive. To further illustrate this point Aristotle gave the example of a ship being wrecked. If the pilot of a ship is not on the bridge and the ship crashes into rocks and becomes wrecked it is due to the absence of a pilot. The pilot himself did no wrong; he was not inattentive or inebriated during duty; he merely was not there. It was the absence of the pilot which caused the ship to crash. This illustrates that negative things occur when there is an absence of some good which should have been there.

St. Augustine took Aristotle’s work on absence and applied it to his own work on the problem of evil, and the idea that something negative was the absence of something positive became a central theme in his theology. Augustine did make some changes to the idea of evil being an absence of good as he believed that not every single absence is an evil; he did this by stating the difference between a privation and an absence. The distinction he made is this; an absence exists when some good is not present that should not be present in the first place whereas a privation (privatio bonni (a privation of good)) exists when some good is not present that should have been there in the first place. To illustrate this a few examples are useful. If a stone does not have eyes then there is an absence of some good but the stone is not intended to have eyes so this seen as an absence not a privation. If a person does not have wings then there is an absence of some good, but the person is not intended to have wings so this is seen as an absence and not a privation. Now if we look at privation then the difference should be clear. If a person does not have eyes then this is a privation and not an absence as a person is intended to have eyes, there is something missing which should be there. If a giraffe does not have a neck then this is seen as a privation and not an absence as there is something missing which should be there. In other words; if something falls short of what it is supposed to be then it has suffered a privation. Who decides the way something is supposed to be is God. It is God who created everything to have a certain nature and if something falls short of this God given nature then it is suffering a privation. Furthermore; if something falls short of its God given nature then it is not as God intended it to be, thus, it is to an extent evil. So the person without eyes is suffering, to a certain extent, from an evil (a privation of good). It is important to note here that these privations do not occur from free choice; they are existent because of some ‘natural evil’ which occurred; for example a birth defect. No choice was made by the person to have no eyes; it was not because of a choice they made. So if these types of privation are seen as natural evil then what is moral evilHow does moral evil occur?

St. Augustine believed that human beings and angels were different to the rest of God’s creations. What they had, which God’s other creations did not, was free will. Where all of God’s other creations were susceptible only to natural evil (they had no choice over the privations which they may have suffered) humans and angels had the ability to choose whether or not they wanted to fall short of God’s intended nature for them. A human being has the choice to be good, to help those who need help or to act in a godly manner and the choice to not be good, the choice to fall short of God’s intended nature. They have freedom; the freedom to act in the right way or in the wrong way. They can choose to act in a manner that makes them fall short of God’s intended nature (as in the story of Adam and Eve). So in other words; moral evil occurs when humans use their freedom to fall short of God’s intended plans for them. Because humans have this free choice where all of God’s other creations do not it is humans which are responsible for all moral evil. Augustine also believed that there was a mysterious connection between human’s free choice to fall short of Gods intentions and the occurrence of natural evil; he thought there was a link between choosing to act in the wrong way and the occurrence of natural disasters. He took the biblical account of creation totally literally and from that he assumed that God created the world without any ‘natural evil’ whatsoever. There would have been no earthquakes, there would have been no tsunamis and there would have been no volcanic explosions (in fact there would have been no volcanos at all). He believed that all of these features of the world were brought about by humans and angels using their free choice to rebel against God. So now the background to Aquinas’ theology has been established we can look at Aquinas’ work in some detail.

St. Thomas Aquinas’ approach to the problem of evil took much from Aristotle and Augustine. Like Aristotle he saw that many negative things can be seen to be an absence of something else, i.e. darkness being an absence of light. He also saw the need to make a distinction between absence and privation, for he too believed that it was not evil for a stone to not have eyes. He took these ideas and expanded on them to create a much more detailed view of what evil can be seen to be. He states ‘For evil is the absence of the good, which is natural and due to a thing’. He stated that pure evil is totally impossible and this is due to two reasons. If pure evil was possible then it would imply that there was a separate force of evil, opposed to that of good. If this were the case then it would mean that God was either not utterly good, or it would mean that God was not omnipotent. It would also negate the idea that evil is an absence of good. The other reason that Aquinas stated that pure evil was impossible is that for something to be purely evil, by definition, it would have to fall short of its God given nature by 100%. As God created everything that exists then something that fell short of its God given nature by 100% would not exist. Even Satan, according to Aquinas, cannot be seen to be totally evil. Satan was created by God and is evil because he chose to rebel against his God given nature but he is good in the fact that he exists and is one of Gods creations. Another example would be that of Chairman Mao. Chairman Mao was good to the extent that he existed but was bad because he failed to live up to God’s intended nature for him (because he killed around 10 million people). So, for Aquinas as for Augustine, pure evil does not exist.

Another feature that Aquinas added to Augustine’s work was the differentiation between evil suffered and evil done. It is evil done that creates moral evil. It is not evil to have a thief steal your wallet; there is evil in the crime and the person who has been robbed has suffered from evil but they have committed no evil themselves, they have done nothing morally wrong and they have created no moral evil. It is the thief who has done something wrong; he has committed an evil act and has created some moral evil.

So far it appears that Aquinas’ and Augustine’s approach to the problem of evil are the same (if not for a few revised definitions and differentiations). Where Aquinas really made a difference was with his work on the idea of natural evil. Unlike Augustine Aquinas effectively denied that natural evil exists. He did not believe that volcanoes and tsunamis were brought about by the free choices of angels and humans. Furthermore he did not believe that the world was created without things such as volcanoes and tsunamis, flesh eating tigers and fatal illnesses. He believed that all of things have always existed from the moment of creation and all of these things were created by God for a reason. The things which we may view as evil are only evil from a homocentric perspective; we only see tsunami’s as being evil because they kill other humans. We only see flesh eating tigers as evil because they are a threat to us. These things which we view as evil are only seen as evil from our perspective. Aquinas’s approach does not look at the world from a homocentric perspective; instead he looks at the world from the perspective of god (a theocentric perspective).

When the world is looked at from God’s perspective what is seen as evil changes vastly. When a tiger eats a human or even a baby this not evil. The tiger is fulfilling its God given nature perfectly when it kills other beings to eat them. God designed the tiger to eat meat to sustain its own life; if it did not eat meat to sustain its own life then it would not be fulfilling its God given nature and then it would be succumbing to evil (it would be falling short of God’s intentions for it). Even the recent tsunami in Japan, according to Aquinas, cannot be seen as a natural evil. He would say that the tsunami was good in that it was fulfilling its God given nature to the fullest extent. The tsunami did what it was intended to do. It was being a good Tsunami. All of God’s creations are seen to be good if they fulfil their God given nature, if they do what God intended them to do. A volcano that erupts is a good volcano, a sheep that eats grass is a good sheep, and a fox which eats chickens is a good fox and so on. Obviously from the chicken’s perspective it is a bad thing that the fox eats it but from God’s perspective the fox is being a good fox because it is acting as God intended it to act. If the chickens were not killed by foxes or any other animal there could be a situation where there were too many chickens and this could lead to other problems such as chickens eating all the food and leaving none for other animals. In the same way if there were no disasters such as tsunamis then there could be too many humans in the world and this would leave no food for God’s other creatures. The same applies to things such as the AIDS virus. Although we see it is a very bad thing, in God’s eyes it may be seen as necessary to keep the population at a certain level without overcrowding. Because the AIDS virus was created by God it is not evil if it fulfils its God given nature. It is only from a human perspective that the AIDS virus is seen as a bad thing.

This is a philosophically interesting and attractive position to take on the problem of evil. Aquinas’ approach not only deals with moral evil in an effective manner but also explains what Augustine would call ‘natural evil’ in a much more logical way. Aquinas’ decision to look at the world from a theocentric perspective allowed him to explain things such as tsunami’s and AIDS without turning to mysterious effects of moral evils. In effect Aquinas took Aristotle’s conception of a ‘good man’ or a ‘good carpenter’ and extended it to encompass all of God’s creations and in doing so created a much more philosophically sound approach to the problem of evil.

One problem with Aquinas’ approach to the problem of evil is that he does not explain what use evil has. Why is evil allowed to be prevalent in the worldWhy does God allow so much suffering to occurAlthough Aquinas states that evil is not ‘something’, it is an absence of good he does not explain why God allows man to fall so short of our intended nature and thus allow evil to exist (even if its existence can only be explained in terms of a lack of good). One theologian who does manage to explain why evil exists is John Hick. Hick rejects much of the traditional Christian approach to the problem of evil and states that the ideas which underlie much of traditional Christian theology are false and effectively outdated. It is now useful to look at Hick’s approach to the problem of evil to see how it differs from Aquinas’ approach and to see whether it manages to successfully account for why evil is allowed to exist in the world.

John Hick is a British philosopher and theologian who effectively denies much of traditional Christian beliefs. For example he denies that the humans were ever perfect and in doing so he denies the story of ‘the fall’. He does this by looking at scientific research and using this to show that it is very improbable that humans were ever perfect, improbable that the Garden of Eden existed. This is radically opposed to Aquinas’ view as Aquinas was a firm believer in the story of ‘the fall’, from which stemmed all evil.

Hick took much inspiration from St Ireneus who believed that human kind was created in God’s image. We were created to look like God but it was our responsibility to become like God. It is our responsibility to grow morally through our own free choices. We must choose to live a way of life that reflects the ‘divine’ way of life, we must choose to act in the way that God would. But how can we do thisHow can we grow to become more like GodHick believes that we can grow to become like God through our own free choices. Through our choice to act in the right way and not commit evil acts or give in to our weaknesses we can grow morally and spiritually to become more like God. Hick goes on to state that the evil which exists in the world is part of God’s creation. The evil which we find all too easy to give into was created by God as a gift. It is through this evil that we can grow into God’s likeness. We can choose not to give in to our base desires and do the wrong thing. We can choose not to remain in our animal state and accept that ‘we are only human’. We can choose to adopt the features of God such as kindness, compassion and love and if we do we grow spiritually and grow away from our animal state.

So Hick believed that evil was put into the world to allow us to make free choices; choices between right and wrong, good and evil. He developed this line of reasoning in an attempt to prove that a belief in an all powerful, all good and all loving God was not an irrational belief. But this still begs the question; if God wants us to believe in him and act in the right way why does he not prove his existence to usWhy doesn’t he show himself to usIt would seem like the sensible thing to do, it would stop all speculation over whether God exists or not and it would be very likely that people would stop acting in an evil way. Hick claims that God does not show himself to us in order to protect human free will. God chooses to remain hidden to preserve our freedom. This allows us the make our own choices and to choose to act how we want. It is this freedom, according to Hick, which allows us to grow morally and spiritually and thus grow into God’s likeness. If God did show himself then this would destroy our free choices and thus stunt our moral and spiritual development.

So; God cannot show himself as it would destroy human freedom, it would destroy our freedom to act in whichever way we please. Without this freedom we would not be able to grow into God’s likeness. So it is evil which allows us to become more like God. It is evil which makes us more moral beings. This approach to the problem of evil does overcome some of the objections faced by Aquinas’ approach as it manages to explain why God permits evil to exist in the world. The approach devised by Hick’s manages to justify why belief in an all powerful, all good and all loving God is not irrational in the face of great evil. This is something which Aquinas fails to do. Aquinas does manage to explain how there is evil in the world but not why.

To conclude I have found that Aquinas’ approach, despite it underpinning much of Catholic belief, fails to account for why God permits evil to exist in the world. Aquinas does manage to explain how it exists and blames this on the bad choices of humans but he fails to explain why it exists. He fails to give evil any purpose unlike Hick who explains why and how evil exists in the world. Hick states that God gave us evil as a gift which will bring about the highest good and he explains this point well. So, although Aquinas does give a fairly good account of how evil exists and makes a good point in stating that natural evil does not exist, he fails to justify or explain why evil is permitted in this world. Because of this I am inclined to reject Aquinas’ pre-scientific theory in favour of the better explained, more scientific and more plausible theory devised by Hick.


Herbert McCabe. God and Evil: in the theology of St. Thomas Aquinas. Continuum international publishing group. 2010

Peter Vardy. A thinker’s guide to evil. John Hunt Publishing. 2003

Peter Vardy. A thinkers guide to god. John Hunt publishing. 2003