Andrew Sullivan lays out his tax philosophy.
To put it as plainly as I can: I don't believe in a governmental attempt to engineer a substantively "fair" society through taxation. I see taxation as a necessary evil to pay for those few social goods that private individuals cannot provide for themselves.
Government's primary concern is to raise money as efficiently and as leanly and as equally as possible. I'm happy with the government then setting up programs to assist the poor, to provide better education for those at the bottom, safety-net healthcare and better policing. i.e. to gear spending toward social ends that might help the poor the most. These are measurable, practical goods. What I'm not happy with is the assumption that tax policy should really be about redistributing wealth, and engineering substantive economic outcomes.
I generally agree with this, if for no other reason than the fact that attempting to use the tax code for broader purposes has resulted in a complex, almost universally hated mess that fails to achieve the larger goals anyway.