On the Urban thread, Jonathan Green pointed out that the major issue with oil scarcity may not be how much oil we have in the ground, but how much we can pump in a given year. If we are maxed out on supply for a year, any oil disaster creates a huge crunch. So once we hit peak capacity, we’ll end up with large price spikes anytime supply is interrupted anywhere. This creates risk for consumers that they’d rather not have, and so markets tend to give people options to get rid of that risk, at a price.
One solution to these price spikes is that higher prices will signal that there is money to be made in stockpiling and waiting for a high price (buy low, sell high). This would mitigate the price spikes by creating extra stockpiled capacity when bad things happen. It is similar in spirit to opening the strategic petroleum reserves when prices get high, except without the politics.
Except, of course, for the politics! Because if you stockpile oil to sell when prices spike, not only are you providing a public service, you are hoping to receive “windfall profits”. In fact, those windfall profits, in a well-functioning market, rise precisely as your stockpile-selling is valuable to others.
So one effect of a large tax on windfall profits would be to reduce the incentive to stockpile (since those profits will be taxed away). Nor, really, are the profits likely to be a “windfall” in any meaningful sense. The stockholders get those profits because they took on the risk of oil prices so consumers would face less risk.
So I’m not in favor of that kind of taxation. On the other hand, if we think oil is creating all sorts of nasty externalities, like pollution and national security problems, then I’d favor higher gas taxes. Ideally, the size of the tax would reflect the social cost created by the gasoline. Even better would be to create a market in automobile emissions, but I don’t think we’re quite there yet.