Originally Posted by Gianakin_
He knew damn well what he did wasn't right and good. That's why he has that look on his face in the Temple and that's why he's crying when he tells Padme about the Tusken. That's also why he sheds a tear after slaughtering the Separatists.
That doesn't change the fact he was stupid enough to get tricked into being Darth Vader. The way Obi-Wan told it in Jedi it sounded like there was this long decline, Obi-Wan spent a lot of time trying to reach out to Vader as he got worse and worse until eventually he just lost all faith that the man he once knew and loved even existed, it was like an addiction. Vader even references the addictive aspect when he somberly says "it's too late for me...son" or when he says "You don't know the power of the Darkside, I must obey my master". Here Palpatine got Anakin's attention with a story about how he can save people from dying and how he knew everything his master taught him. Then he specifically says, "the power to cheat death has been lost for...".
Not to mention the movie was shot with Anakins primary motives being a change of heart believing the Jedi were the true evil in the galaxy (Hense the part where palpatine tells him he's fore-filled his destiny, "From my point of view the Jedi are evil", all the scenes building tension between Anakin and the Jedi, the Jedi asking him to spy on his friend). Then in reshoots and editing Lucas wanted to change Padme to the primary motive.