That's what he claimed on Meet the Press. Either he's lying or else an inane belief system guides his fiscal policy.
"It's critical to get the country on track to avoid the kind of financial calamity you're seeing around Europe, and I have a plan that does that," he said. "There's nothing wrong with the term 'compromise,' but there is something wrong with the term 'abandoning one's principles,' and I'm going to stand by my principles. And those are, I am not going to raise taxes on the American people."
It's perfectly fine to oppose a tax increase in a given situation, or to believe tax hikes are generally bad policy. But opposing any and all tax hikes as a matter of principle, regardless of the effect on the deficit and America's fiscal health, is just dumb. A principle is "a fundamental truth or proposition that serves as the foundation for a system of belief or for a chain of reasoning." Does Romney really think tax rates during the Clinton era violated a fundamental truth?
His answer brings to mind the debate question where the Republican primary candidates were asked if they would agree to a deficit reduction package where tax hikes were paired with spending cuts 10 times as big. Everyone on stage avowed that they would vote against that deal. Given present and projected deficits, there's a word for that position: fiscally irresponsible.
Republicans are fond of pointing out that deficit spending forces future generations to pick up the tab for present goodies, and that the magnitude of our debt and deficits put us at risk of catastrophe. It borders on incoherence and is certainly irresponsible to really believe those things, and yet to reject a significant deficit-reduction compromise anyway. What politicians show when behaving that way is that they don't actually believe their own rhetoric about deficits and prioritize tax rates more than anyone should.
When running a deficit, spending is what matters. Tax rates just determine whether Americans pay now or later for what we're buying. Romney's stance amounts to a "principled" aversion to paying now. Either he breaks his promise on taxes, or he is extraordinarily likely to increase the deficit.