That's another area in which we differ.
I think a flat tax is a progressive tax as well, because there always is a basic exemption of a certain amount. If you look at Alberta, it's fairly healthy. Normally in flat-tax proposals what people put forward is an increase in the amount of basic income that's exempt, so that the proposals normally deliver a benefit to low-income people. They also deliver a benefit to very high-income people—that's inescapable—but if you arrange it so that there's sufficient benefit to the low-income people, then many observers who look at it will say that on distributional grounds it may improve things.
Another point to keep in mind is that the marginal tax structure doesn't just come from the personal income tax system. It also comes from the CPP, EI contributions, and clawbacks. When you add them all together and look at the effective structure of marginal tax rates, actually the marginal tax rates are at the highest for some of the lowest-income people. Beyond that it's a bit jagged if you add the whole thing up, but the marginal tax rate on average is about constant as you go up, because the very high-income people are not making EI and CPP contributions, for example, on their marginal income, and the two things just cancel out.
Some people think one could rationalize this whole system and simplify things by having one constant marginal tax rate for everybody. This would be a very radical reform. It would require a wholesale rethinking of the whole system, but I think if people are thinking about flat-tax ideas, they ought to think in those terms.