[MUSIC] Here's a slightly more technical way to think through these taxes. The government has a two step process. The first step is to figure out what the efficient quantity is to make sure that the sum of the marginal benefit is greater than and as close as possible to the marginal cost. Once the government decides what the efficient quantity is, it has to create a tax. And the typical tax has to have two characteristics. First of all, it has to satisfy a budget constraint. We must collect enough taxes. So the sum of the taxes from all the people in our society has to be greater than the cost of providing the efficient outcome on the efficient quantity of the good. The second characteristic is that we must have some sort of a participation constraint. We must have everyone agree to the tax. In other words, the benefit at the efficient quantity, has to be greater than the tax that the person pays. The participation constraint is what allows us to vote for the tax. And how many of us need to vote for the tax, really depends on the political framework that we are working under. If we're talking about a majority rule, we would need at least half of us to have the participation constraint suffice. From an equity perspective, we might decide that we want everyone's participation constraint to hold, so that no one will oppose to this tax. I want to point out that from an efficiency perspective, the second rule does not need to hold. From a efficiency perspective, all we care about is that we're producing the efficient amount. It might be completely inequitable to have one person pay for the whole thing, but from an efficiency perspective, that would hold, and that would be correct.