The long term budget deficit is about one thing: medical costs. It's not about "entitlements." Social Security isn't a long run problem of any serious consequence, nor are various small programs that count as entitlements in the budget process. Long-term projections of the federal budget are very clear. It's all about health care.
Medical costs. Medical costs are going up much faster than inflation. Therefore, Medicare and Medicaid, and any other government programs affected by medical costs, will, long term, get far more expensive than any realistic level of taxation can handle.
So when budget hawks talk about "entitlements," as Andrew Sullivan did today, they're using language that in my view obscures, rather than illuminates, the situation.
Now, I'd go a bit further, as others have done. I agree with those who have argued that health care isn't really, properly speaking, a federal budget problem. It's a serious problem for the American economy. Thinking of it as a budget deficit problem misses the point; shut down Medicare completely and you solve the budget deficit part of it, but you still have an important dysfunctional situation with regard to health care.
Either way, I agree with Jonathan Chait: the way to measure a politician on federal budget deficits is really just to measure whether he or she has made medical costs a priority.
Now, and here's the part in which I give me own views of these things, I'll admit that I simply don't buy the idea that budget deficits have something to do with the future (it's not as if all those under-30s who voted for Obama are going to have to pay back the deficits when they "come due" down the line -- but they are among those who are badly hurt by a recession-level employment situation, which in my view could have been alleviated with more deficit spending over the last few years). That's a policy opinion, and others may and do disagree.
But as far as talking about budget deficits, there's really no question about it. It's health care costs. Most of the rest of what people are talking about is either stuff around the margins (important! -- government should be run properly! -- but it's not going to change the long-term deficit situation), or is about the preferred size or functions of government, not about deficits at all (well, there's the conservative position, which I interpret as pro-deficit, but that's a slightly different issue).
Getting back to my main point...in my view, those who are upset about the long-term federal budget deficit should talk about it in terms of what it is, health care costs. Just as the phrase "weapons of mass destruction" encourages sloppy thinking (because nuclear weapons are not really similar at all to chemical and biological weapons in lots of important ways), talking about "entitlements" confuses the budget situation. I could see "Medicare and Medicaid" or, perhaps, "government health programs," but not entitlements.