the Ratzinger argument or any other that state that we may in good conscience vote for those who hold morally repugnant views about what policy should be. There is no proportionate reason for direct support (through voting) of evil.
In a follow-up comment, Zippy suggests voting is unlikely to be an act of only mediate material cooperation in the evil the candidate promises to do if elected.
My perspective: Either I missed an encyclical, or the Church is still in a period of discernment regarding this whole representative democracy wheeze. So when, for example, Cardinal Ratzinger writes that voting for a candidate despite his immoral policies is remote material cooperation, I take it to be a well-reasoned but somewhat ad hoc application of the cooperation-with-evil theory to representational elections.
Now, the CWE theory describes the relationship between two specific, discrete acts. One of these acts is, of course, the act of voting for a candidate who advocates immoral policies. But... what is the other act?
I think a lot of people assume the other act is an instance of the root evil that makes the policy immoral -- a procured abortion, say, or a killing during an unjust war. Being the root evil, such an act is as remote from voting as possible. "All I did was vote for the guy with the best health care plan," the reasoning might go, "I didn't make anyone get an abortion."
Between these two acts, though, lies the act of the legislator voting for (or the executive enforcing) an immoral law or action. It isn't always appreciated that -- despite the special pleading of many politicians who claim their actions are justified -- voting for or enforcing an immoral law is an immoral act, and not just by cooperation!
Remember, cooperation relates two discrete acts. Voting for an immoral law is immoral because it is a corruption of the very nature of human law. Even if there is no root evil act with which a legislator is cooperating, voting for an immoral law is immoral. (This can be seen clearly, I think, in the case of a vote on an immoral law that fails. If a proposed law never gets approved, there won't be any "root evil acts" performed because of it, but it's still immoral to vote for it.)
So I think the question is, is Cardinal Ratzinger right to say the relationship between a citizen's vote for a legislator and a legislator's vote for an immoral law is one of remote material cooperation?