In Wednesday’s much-hyped verbal slugfest between Barack Obama and Mitt Romney, few topics will loom larger than taxes. They’re a central battlefield for Republicans and Democrats, an area in which the two parties are fundamentally, philosophically divided. For much of the past four years, the Bush tax cuts, the capital gains tax rate, and the oft-repeated (and heavily spun) fact that 47% of Americans don’t pay federal income tax have been at the heart of Washington’s conflicts, and have often spilled over into other battles like the fights over health care reform and the debt ceiling.