The Epicurean paradox or riddle of Epicurus or Epicurus’ trilemma is a version of the problem of evil.
Lactantius attributes this trilemma to Epicurus in De Ira Dei, 13, 20-21:
God, he says, either wishes to take away evils, and is unable; or He is able, and is unwilling; or He is neither willing nor able, or He is both willing and able. If He is willing and is unable, He is feeble, which is not in accordance with the character of God; if He is able and unwilling, He is envious, which is equally at variance with God; if He is neither willing nor able, He is both envious and feeble, and therefore not God; if He is both willing and able, which alone is suitable to God, from what source then are evils? Or why does He not remove them?
In Dialogues concerning Natural Religion (1779), David Hume also attributes the argument to Epicurus:
Epicurus’s old questions are yet unanswered. Is he 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?
No extant writings of Epicurus contain this argument. However, the vast majority of Epicurus’s writings have been lost and it is possible that some form of this argument may have been found in his lost treatise On the Gods, which Diogenes Laërtius describes as one of his greatest works. If Epicurus really did make some form of this argument, it would not have been an argument against the existence of deities, but rather an argument against divine providence. Epicurus’s extant writings demonstrate that he did believe in the existence of deities. Furthermore, religion was such an integral part of daily life in Greece during the early Hellenistic Period that it is doubtful anyone during that period could have been an atheist in the modern sense of the word. Instead, the Greek word ἄθεος (átheos), meaning “without a god”, was used as a term of abuse, not as an attempt to describe a person’s beliefs.