The problem of evil, also known as the problem of suffering, is the philosophical question of how to reconcile the existence of evil and suffering with the notion of an omnipotent, omnibenevolent, and omniscient God. There are currently differing definitions of these concepts. The best known presentation of the problem is attributed to the Greek philosopher Epicurus.

Besides the philosophy of religion, the problem of evil is also important to the fields of theology and ethics. There are also many discussions of evil and associated problems in other philosophical fields, such as secular ethics and evolutionary ethics. But as usually understood, the problem of evil is posed in a theological context. The problem of evil has been extended to non-human life forms, to include suffering of non-human animal species from natural evils and human cruelty against them.

Definitions

Evil

In the context of the problem of evil, a broad concept of evil is typically used that encompasses "any bad state of affairs, wrongful action, or character flaw". These may be either natural evils or moral evils including minor harm or injustice, in contrast to the modern colloquial use of "evil" commonly associated with particularly horrendous moral acts. More restrictive definitions of evil are sometimes used in particular formulations and responses. Marcus Singer says that a usable definition of evil must be based on the knowledge that: "If something is really evil, it can't be necessary, and if it is really necessary, it can't be evil".

The concept of evil can take on different meanings when seen from the perspective of different belief systems. While evil can be viewed in religious terms, it can also be understood in natural or secular terms, such as social vice, egoism, criminality, and sociopathology.

Omniqualities

Omniscience is the property of having complete or "maximal knowledge". Maximal is not necessarily unlimited, but limited to "God knowing what is knowable". This is the most widely accepted view of omniscience among scholars of the twenty-first century, and is what William Hasker calls freewill-theism. Within this view, future events that depend upon choices made by individuals with free will are unknowable until they occur. According to the philosophers Hoffman and Rosenkrantz: "An omnipotent agent is not required to bring about an impossible state of affairs... maximal power has logical and temporal limitations, including the limitation that an omnipotent agent cannot bring about, i.e., cause, another agent's free decision".

Defenses and theodicies

Responses to the problem of evil have occasionally been classified as defences or theodicies, although authors disagree on the exact definitions. Generally, a defense refers to attempts to address the logical argument of evil that says "it is logically impossible – not just unlikely – that God exists".

A theodicy, on the other hand, is more ambitious, since it attempts to provide a plausible justification – a morally or philosophically sufficient reason – for the existence of evil. This is intended to weaken the evidential argument which uses the reality of evil to argue that the existence of God is unlikely.

Formulation

The problem of evil refers to the challenge of reconciling the existence of evil and suffering with our view of the world, especially but not exclusively, with belief in an omnipotent, omnibenevolent, and omniscient God who acts in the world.

The problem of evil may be described either experientially or theoretically. Theoretically, the problem is usually described and studied by religion scholars in two varieties: the logical problem and the evidential problem.

Logical problem of evil<!--'Logical problem of evil' redirects here-->

thumb|right|upright|The earliest statement of the problem of evil is attributed to Epicurus, but this attribution is uncertain.

The problem of evil possibly originates from the Greek philosopher Epicurus (341–270 BCE). Hume summarizes Epicurus's version of the problem as follows:

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"Is [god] willing to prevent evil, but not able? then is he impotent. Is he able, but not willing? then is he malevolent. Is he both able and willing? whence then is evil?"

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The logical argument from evil is as follows:

This argument is of the form : if its premise (P1) is true, the conclusion (C1) follows of necessity. To show that the first premise is plausible, subsequent versions tend to expand on it, such as this modern example: Both absolute versions and relative versions of the evidential problems of evil are presented below.

A version by William L. Rowe:

  1. There exist instances of intense suffering which an omnipotent, omniscient being could have prevented without thereby losing some greater good or permitting some evil equally bad or worse.
  2. An omniscient, wholly good being would prevent the occurrence of any intense suffering it could, unless it could not do so without thereby losing some greater good or permitting some evil equally bad or worse.
  3. (Therefore) There does not exist an omnipotent, omniscient, wholly good being.

Skeptical theism is an example of a theistic challenge to the premises in these arguments.

Problem of evil and animal suffering

thumb|right|upright=1.3|[[William L. Rowe's example of natural evil: "In some distant forest lightning strikes a dead tree, resulting in a forest fire. In the fire a fawn is trapped, horribly burned, and lies in terrible agony for several days before death relieves its suffering." Rowe also cites the example of human evil where an innocent child is a victim of violence and thereby suffers. One version of this problem includes animal suffering from natural evil, such as the violence and fear faced by animals from predators, natural disasters, over the history of evolution. This is also referred to as the Darwinian problem of evil,

The second version of the problem of evil applied to animals, and avoidable suffering experienced by them, is one caused by some human beings, such as from animal cruelty or when they are shot or slaughtered. This version of the problem of evil has been used by scholars including John Hick to counter the responses and defenses to the problem of evil such as suffering being a means to perfect the morals and greater good because animals are innocent, helpless, amoral but sentient victims. Scholar Michael Almeida said this was "perhaps the most serious and difficult" version of the problem of evil. The problem of evil in the context of animal suffering, states Almeida, can be stated as: