Musar על סנהדרין 114:6

The sin of the golden calf involved three distinct kinds of death penalty. Those who had been warned by reliable witnesses were executed by the Levites. Those who worshipped the golden calf but could not be executed judicially because although there were witnesses against them they had not been properly warned, were killed by a dragon; those who were guilty but against whom there were no valid witnesses died by the plague. Something similar happened in the case of the seduction by the serpent. Adam had been warned not to eat, the penalty spelled out. G–d Himself was the witness in his case. Eve was guilty because G–d had stated in Genesis 2,24: "Therefore man leaves the home of his parents and cleaves to his wife." Rashi sees in this the prohibition of the different kinds of incest that apply to all of mankind. However, she had not been warned that the penalty for contravening this law was death. The serpent's sin was committed with neither forewarning nor the testimony of an independent witness against it. We have a halachic rule that one does not use any argument that can serve as an extenuating circumstance on behalf of a seducer (Sanhedrin 29). Adam rehabilitated himself by offering an ox, as explained by our sages (Shabbat 28). When the Jewish people made the golden calf they reversed what Adam had done by exchanging the true G–d for the image of an ox.