Megan's debate with Henry Farrell over voluntary taxation is fun to watch. Megan says if you think you are not paying your fair share in taxes, then you can always write a check to the government. She is correct. Henry says that when people say that they want to pay higher taxes, generally they mean that they want to pay conditional on other people also paying higher taxes. It may be well worth $x to me to increase government revenue by $10,000,000x, e.g., but not to increase it just by $x. He is correct.
I accept Henry's reasoning. But a lot of folks with roughly his politics don't. I've heard any number of ethical vegetarians reject the claim that the irrelevance of any individual's choice to the aggregate demand for meat renders the individual's obligation not to consume meat moot. Likewise, there is no change in my behavior that could possibly have a causally appreciable affect on the aggregate output of carbon. But there are evidently many many people who think I am under a strong moral obligation to bicycle, buy local produce, etc. whether or not a credible scheme of global carbon regulation is ever implemented. And aren't a lot of the people who think they should not eat meat whether or not other people do, and a lot of the people who think that they should reduce their carbon footprint whether or not other people do, the same people who think tax rates ought to be higher as a matter of distributive justice? If so, then it seems like those people are logically committed to sending big checks to the government, or directly to poor people, whether or not other people are forced to. And so it does seem that many people who should think they ought to are avoiding sending checks to the government.
Maybe if there was a special “tax patriot” armband you got to wear around for paying extra taxes that allowed people to signal, and take public credit for, an otherwise invisible act — a Prius of taxation — we'd see more of it.