In Dialogus cum Tryphone, Justin Martyr declares that angels and humans possess free will. However, what does free will entail? What does Justin mean by the expression?
First, it is important to define free will, which is by no means an easy task. William Ockham defined free will as "That power whereby I can do diverse things indifferently and contingently, such that I cause, or not cause, the same effect, when all conditions other than this power are the same." William Hasker calls this definition both exact and exacting. He prefers to define (libertarian) free will as "the power to perform A (i.e. a particular act under given circumstances) or to refrain from performing A" (See _God, Time, and Knowledge_, p. 66).
On the other hand, others think of free will as the ability to act in accord with one's nature. As mentioned earlier, saying exactly what free will is, is not a facile task. Critical for the present discussion is what Justin Martyr thinks of free will. Some passages from the Dialogus provide insight respecting this issue:
"For God, wishing both angels and men, who were endowed with freewill, and at their own disposal, to do whatever He had strengthened each to do, made them so, that if they chose the things acceptable to Himself, He would keep them free from death and from punishment; but that if they did evil, He would punish each as He sees fit" (Dial. 88).
"He created both angels and men free to do that which is righteous, and He appointed periods of time during which He knew it would be good for them to have the exercise of free-will; and because He likewise knew it would be good, He made general and particular judgments; each one's freedom of will, however, being guarded" (Dial. 102).
"But that you may not have a pretext for saying that Christ must have been crucified, and that those who transgressed must have been among your nation, and that the matter could not have been otherwise, I said briefly by anticipation, that God, wishing men and angels to follow His will, resolved to create them free to do righteousness; possessing reason, that they may know by whom they are created, and through whom they, not existing formerly, do now exist; and with a law that they should be judged by Him, if they do anything contrary to right reason: and of ourselves we, men and angels, shall be convicted of having acted sinfully, unless we repent beforehand. But if the word of God foretells that some angels and men shall be certainly punished, it did so because it foreknew that they would be unchangeably [wicked], but not because God had created them so" (Dial. 141).
In 1 Apology 43, Justin argues that a lack of free volition negates human blame, merit or responsibility. While some persons claiming to be Christian may not have a problem with vitiating human merit, arguing that man is not free but determined also seems to eviscerate human responsibility or blame. There can be no legal concept of MENS REA nor any divine concept of wickedness unless humans are free to choose good or evil. This is, at least, how Justin reasons. Justin contends that God gave humans and angels free will in order to choose the good. However, being free also means that one could freely elect to do that which is unpleasing to the Father and God of all. Since, God created angels and humans with free will, however, those who unrepentantly turn aside from the righteous commandment of Jehovah God will be justly punished. Justin thus appears to define free will in the following terms: "For neither would any of them [i.e. humans or angels] be praiseworthy unless there were power to turn to both (virtue and vice)."