Anakin's fall fits the parameters of that definition, though. It's just that fear, rather than anger, is his impetus. Which it can be -- Yoda says in ESB that "anger, fear, aggression" are paths to the Dark Side. His fear of loss and of not being in control are his primary motivators. In terms of falling to evil, there's always a level of choice involved -- and Anakin's is exactly that. He chooses to act as he does based on his fears and his selfish desires and then rationalizes his actions as being for the greater good. I disagree. Anakin's turn isn't a twenty second decision. It spans the entirety of all three films with that final submission to Palpatine being the final culmination of his journey to the tipping point. It began with his separation from his mother in TPM and when Yoda remarks that he is afraid to lose her -- that fear leads to anger, anger to hate, and hate to suffering. Anakin's turn is no submission to Palpatine -- rather it's him making a power grab. He has decided that he will have the power he's always dreamed about (the power to cheat death among them) and if Palpatine is a vehicle to that then so be it -- he flat out states in ROTS that he plans to overthrow him. And Anakin in ROTJ knows that he is evil. That it is "too late" for him. That, and believing in a cause doesn't necessarily mean you are blind to the evil you have done in service of it. Additionally, in regards to AOTC, if the standard of falling to the Dark Side means killing people in a rage when you watch someone you care about die, then Luke fell in A New Hope. He killed those stormtroopers out of anger right after Obi-Wan let himself be killed and only stopped when he heard Obi-Wan's voice compelling him to run. I disagree. If anything, I think Padmé's death would have made Anakin hate himself but not rescind on the Dark Side in the slightest -- especially after his duel with Obi-Wan. Because you can't forget that Anakin still believes in the Empire -- he still believes that an Empire will bring order to the galaxy, will make people's lives better, will provide greater justice and security. You say that Anakin "otherwise opposes" Palpatine. But where is the evidence of this? If anything, Anakin believes quite strongly in Palpatine's "reorganization" of the Republic. He thinks it is good that the Chancellor's office is gaining more power, he thinks the Republic as a system is nonfunctional, he thinks action over deliberation is ideal, he believes that an empire will bring "peace, freedom, justice, and security." As in the OT, Anakin intends to kill Palpatine and lead the Empire, but he doesn't oppose the formation of the Empire. It fits in line perfectly with his offer to Luke to use their combined strength to take out Palpatine, end the war, and bring order to the galaxy.