Justin Martyr’s Problem with Platonism: Heresy and Anthropology in Dialogue 4 and the Syntagma

In Dialogue 4, Justin changes his mind on two specific tenets of Platonic philosophy: the idea that the soul can see God, and the doctrine of transmigration. The Platonic anthropology rejected by Justin happens to be foundational to the theological systems of his Christian demiurgical opponents: Simon and Helen, Basilides, and Carpocrates (who are likely discussed and refuted in Justin’s now-lost Syntagma Against all the Heresies). In this paper, I argue that this is not coincidental, and that Justin’s problem with Platonic anthropology is bound up with his broader heresiological concerns. By rejecting these two doctrines, Justin was able to define Christianity on his own terms while effectively undermining the teachings of his religious rivals. This further explains the specificity of Justin’s problem with Platonism, which should not be read as a wholesale rejection of Platonic philosophy.