Writing in the St. Louis Beacon, Washington University professor of Earth and planetary sciences Bob Criss argues that raising the Missouri gas tax could solve a number of environmental and social ills. Although I’m opposed to pretty much all taxes, I’m somewhat amenable to Criss’ argument. If we have to tax something, it is far better to tax something no one wants, like pollution, than to tax something everyone wants, like income (or general consumption, for that matter).

However, the Missouri Constitution makes implementing Criss’ proposal somewhat problematic. The state Constitution requires that funds generated by the gas tax be dedicated to building and repairing roads, bridges, and highways. The goal of a higher gas tax for Criss is that people would use less gasoline by driving less or using more fuel-efficient vehicles, but more and better roads will at least marginally increase people’s incentive to drive by allowing them to reach more destinations more quickly and comfortably. Increased roadwork would also generate a fair amount of air pollution. Those effects probably would not completely eliminate the environmental gains of a higher gas tax, but they are worth considering.

Furthermore, if people drive less but there are more gas tax revenues to spend, we will end up wasting that money on underused roads and highways. In short, while Criss’ proposal is not without merit, implementing it properly would involve a much greater challenge than simply raising the gas tax.