My basic theory of current American politics, especially when it comes to budgets and spending, was forever shaped by an episode early in the time when I worked on Capitol Hill, near the tail end of the George H.W. Bush era. At the time, Republicans (and many conservative Democrats) were pushing a cap on total entitlement spending, an idea that has been resurrected recently. The legislation reached the floor of the Senate, and was widely expected to pass. I wrote a floor statement for my boss, highlighting all the terrible consequences of the idea and all the reasons to vote against it, then went to lunch.

When I got back upstairs, rather than debating the bill, the Senate Majority Leader (George Mitchell, at the time) had started offering amendments: First, exempt from the cap all programs for veterans. It passed—no one votes against veterans. Then, anything affecting people with disabilities. It passed. Then another amendment or two, and suddenly the “entitlement cap” was full of holes—and with so many areas exempted, the cuts it would force on other programs would be massive. The tide changed in a matter of hours and the threadbare cap was voted down.

This has long been the basic rhythm of the Republican/conservative approach to spending: Always keep it to abstractions. Stick to the Balanced Budget Amendment, the line-item veto, discretionary spending caps, entitlement spending caps. Any of these, if enacted, would of course have the effect of dramatic cuts to Medicare, Medicaid, education, and other vital programs. But Republicans could talk about them as if they would just reduce all that other spending—the silly, wasteful programs, or programs for lazy people (or minorities), that Americans are convinced make up much of public spending. Liberals would move the debate to specifics, conservatives would stick with the abstractions, and the result—thankfully—was usually the same inaction as in that stab at the entitlement cap two decades ago. It’s a pattern consistent with the familiar insight, made first by two political scientists in 1964, that Americans are “philosophically conservative” but “operationally liberal.” Conservative Republicans got maximum value from the first instinct, but avoided directly challenging operational liberalism.

The result is better than wholesale slashing of vital programs, but not by much. Republicans, when in power, denigrate government, undermine programs (or even expand them recklessly, as with the Medicare prescription drug benefit), and pass tax cuts—but they avoid actual choices about spending. That pattern reached its peak in the George W. Bush years, but he didn't invent it. Meanwhile, the constant focus of the political debate on austerity and spending forces Democrats, when they come to office with massive deficits, to do the actual work of cutting long-term spending, and spurs a generalized hostility to government that makes it extremely difficult for government to respond adequately to economic challenges or changing circumstances.

This is what makes Paul Ryan sort of interesting. He's not “brave” or “serious” in his plan to slash spending, cut taxes for the wealthy, and essentially reorder the post-New Deal social contract. Nor is he any kind of fiscal conservative: William Saletan could not be more wrong on these two points. But he does seem like he didn't get the memo about the old rule. Sure, the two Ryan budget plans leave many, many budget choices in the realm of the purely abstract—the tax loopholes he would close, for example, and many of his massive cuts to domestic spending on education, environmental protection, and other government services that fall in the realm of “discretionary” spending. But on two major entitlements, Medicaid and Medicare, he went there—with a very specific, consequential plan to turn one into block grants to the states, and the other into vouchers for individuals. This is the most significant break from the standard game since Newt Gingrich's quickly abandoned effort to cut Medicare in 1993-94.

One could argue that these, too, are evasions. They cut the costs of Medicaid and Medicare, but simply by declaring limits on spending. The Medicaid block grant to states would increase only with population growth and inflation. It would be up to states to figure out how to actually cut health care costs. (The easiest way would be to cut Medicaid eligibility.) The Medicare vouchers, in their latest version, are more complicated, but essentially rely on the idea that seniors purchasing insurance with a fixed amount of dollars can use their power as smart consumers to bring costs down—deciding to forego some services, for example. The actual choices are left to others, the states or individual old people.

But still, these are real, measurable cuts to real programs. The middle-class tax benefits Ryan would cut, such as the Refundable Child Tax Credit, are also real, and so are the cuts to education and other discretionary programs—because cutting non-defense discretionary spending to below 2 percent of GDP cannot be done without a major impact on these programs.

Ryan not only embraced these real cuts, he forced House Republicans to vote for them twice, and now he has essentially attached the plan to the presidential ticket. The old game, under which Republicans talk about spending cuts but mostly make sure they get tax cuts and go home, has come to an end. The basic premise of “operational liberalism” will be put to the test, for the first time. If Ryan and Romney win, not only will they be in a position, perhaps even obligated, to carry through with most of the Ryan plan—more than that, some very deep assumptions about American politics will be turned on their head, assumptions generally shared by Republicans and Democrats alike. As consequential as the Ryan budget itself would be, putting it to the test, and winning, would be as profound a transformation as the New Deal, or as FDR's affirming victories in 1934 and 1936.

On the other hand, if Barack Obama wins reelection, and the Ryan plan is defeated, will it be a victory for a more affirmative sense of responsible action on the part of government—represented not just by spending, but by a new commitment to solving public problems? If the Obama campaign presents its challenge to the Ryan-Romney budget in the right way, it could be. It could be much more than just a victory over a deeply flawed pair of candidates with some vulnerabilities. It could be a robust demonstration that the American people value and respect what government does, not just programs that benefit them now, or will, but the kind of broad social insurance provided by Medicaid. After Ryan-Romney, there will be little room for evasions and abstractions such as entitlement caps and balanced budget amendments. And on the particulars, the voters will have made their choice. Because Paul Ryan dropped the old game, he could have as big an impact on American politics if he and his plans are defeated as if he wins.