where does honesty and deception take place in medea?

The greatest difference between Medea and Jason is that she is aware of the gap between ethical behavior and her own actions. Jason manages to deceive himself with his ideas of his own righteousness. Remember Medea's line, spoken not without irony: "And women, though most helpless in doing good deeds, / Are of every evil the cleverest of contrivers" (ll. 408-9). Deprived of a state to rule, the genius becomes a destroyer, and she is fully aware of what she does: "I know indeed what evil I intend to do, / But stronger than all my afterthoughts is my fury, / Fury that brings upon mortals the greatest evils" (ll. 1078-80). Compare this level of honesty with the sanctimonious speeches of Jason, who betrays his wife and children like the fortune-seeking coward that he is, and then pretends that he has done right by them.