Every time we cut capital gains taxes, there has been an increase in revenues.
This particular piece of fiscal nonsense is a bugaboo of Bob Somerby. The reason it is a bugaboo is that it is repeated ad nauseum and no one in the press has the gumption to point out that this is just false. McCain's little lie - don't people know when we cut taxes we increase revenue? - is so often repeated it is considered conventional wisdom. That there is abundant research proving the exact opposite (which is common sense; when you get a pay cut, do you earn more money? Neither does the United States government), but it is ignored. This is Somerby's problem with this particular bit of fiction.
I just wanted to show that the Lie Watch is alive and well. And here we have an example that, when all else fails, choose a lie everyone knows is a lie and no one bothers to contradict with the facts. It makes everyone's job - McCain, his spin/spokesfolks, the press - so much easier.