I do support a flat tax system
I understand the reasoning behind a graduated tax system. The fact is that the more you make (all other things being equal), the more discretionary income you have, the more options you have, the healthier your are, etc. And I do
think that a just and moral society has a certain amount of responsibility to help out those at the bottom end (if you believe in an every-man-for-himself world where those people can go fuck themselves, then we really have nothing to talk about). The problem is that as soon as you give the politicians any room to screw with the taxes, you get favoritism, attempts to hide taxes, special incentives, etc etc etc until we end up with the abortion that is our current tax system (wherever you live). I would vote for a flat tax system simply because I think the simplification would A) force the government to be more responsible, direct, and transparent about money and B) quite likely result in an economic benefit, since people and businesses wouldn't be spending so much effort on tax planning, tax analysis, tax avoidance, yadda yadda. And as for helping the poor, again as soon as the politicians get involved, we get pork-barrelling, favoritism, and so on.
Bottom line: minimalist government, not because I think it's wrong to help the less fortunate, but because I think the current system is creating a lot of the less fortunate.