Dr. Mike Walden, North Carolina Cooperative Extension economist in the College of Agriculture and Life Sciences at N.C. State University, responds:

"Well, what we do is, we look at characteristics of various kinds of taxes and compare these alternative taxes on the basis of these characteristics. For example, size of the tax base. If you have a bigger tax base, you can have a lower rate. Comparing an income tax to a consumption or spending tax, you would have to give the nod here to the income tax because the income base is much larger. So you are going to be able to have a lower tax rate with an income tax than you would with a spending tax.

"Ability to pay is another characteristic that economists consider. And oftentimes people want higher income people to pay more relative to their income. Well, here again you would have to give the nod to the income tax because it's easier to structure an income tax with higher rates for higher income people than it is to structure a spending tax like that.

"On the other hand, volatility. We would like to have a tax that results in tax revenues that don't change a lot over time with the business cycle. Here you would actually give the nod to taxing spending because spending tends to be less volatile - less up and down - than does an income tax.

"Enforcement is a fourth characteristic. Some say that taxing spending is easier to enforce. And then lastly, adjustments. Some people want to be able to adjust a tax - particular tax for different circumstances or people. Probably here the income tax would be better able to do that because you can put provisions in to adjust taxable incomes. That is much harder to do with the spending tax."