Of course you can do either one. If you were to eliminate Medicare, Medicaid, and the health insurance subsidies of Obamacare, there would be no long-term debt problem. Similarly, if you were to raise tax revenues simply to the average level of OECD countries--an increase of about seven percentage points of GDP from the long-term level forecast by the CBO--the debt problem would also vanish. I think one of these solutions is obviously better than the other, and Paul Ryan has the opposite view. But it can be done.
More importantly, the call to "raise revenue" does not mean, as many have assumed, that these CEOs are calling on Congress to raise their taxes. It means they are calling on Congress to raise your taxes.
Fix the Debt is just the latest group claiming that it wants to increase revenues by lowering tax rates and reducing loopholes--after Simpson-Bowles, Domenici-Rivlin, the Gang of Six, and the Committee for a Responsible Federal Budget. This is not surprising, since its organizers include members of Simpson-Bowles, Domenici-Rivlin, and the CRFB. Theoretically, this is possible. But there are two things you have to watch out for.
The first thing is the baseline. Every plan I have seen that claims to lower tax rates and increase revenues--including those mentioned above, which are discussed at the end of chapter 7 of White House Burning--only "increases" revenues from the levels set by the Bush tax cuts of 2001 and 2003. In other words, they assume that those tax cuts are made permanent, even though they are set to expire in two months. Then they raise revenues from what are the lowest levels in recent history. And if you look at the details, they leave tax revenues much closer to George W. Bush levels than to Bill Clinton levels--despite our aging population and increasing health care costs, which require more spending to maintain the same level of benefits for the elderly, not less.
The second thing--and here's the big giveaway--is the capital gains tax rate. For most of these multi-gazillionaires who signed this letter, there's only one number in the tax code that matters: the tax rate on long-term capital gains. That's because most of their compensation comes in stock, either options or restricted stock, and once they retire most of their income will come from gains on their stock portfolios.
They don't care about the mortgage interest deduction, since their mortgages are insignificant to them. They don't care about the employer health care exclusion, since their health plans are insignificant. They don't care about the tax breaks for retirement savings, since for most of them (unlike Mitt Romney), their IRAs are small compared to their taxable accounts. They don't really care about the deduction for charitable contributions: even if you donate 10 percent of your income, your effective tax rate only drops from 15 percent to 13.5 percent.