http://bible.org/seriespage/death
Adam knew that he was alive, but he was a stranger to the subject of death until he heard this word from the Lord. Now he is on his own. He has a knowledge of what is right and what is wrong. He knows that to obey God will mean continuous and unending life and to disobey will bring the sentence of death. The power of choice and the right to decide is now left with man. However, Satan would not allow the situation to go unchallenged. Though he taunted and tempted Eve he could not force her to eat the fruit. Both she and her husband partook of it by their own choice, and in so doing they incurred the displeasure of the Lord. The warning He gave was plain: “In the day that thou eatest thereof thou shalt surely die.” Being holy and righteous in all of His judgments, God could do nothing other than pass the sentence of death.
If Adam was a stranger to the subject of death, did he know and understand what the consequence was? God says, “if you eat you will surely die.” If there was no death in the garden of Eden, then what significance did that word have for Adam? Did he even know what that meant?
It’s kind of a pointless argument, isn’t it? Surely the subject here is the choice between obedience and disobedience, not between life and death.