It must be slowly occurring to the folks at Ronald Reagan's transition headquarters that the ideas that won the election won't suffice to run the government.

Beyond slogans, the Republicans seem to have only a vague philosophy of ruling, and by now they must sense the central contradiction of their position: If they remain faithful to their ideals -- less government, more self-reliance -- they must disappoint, even turn upon, their own middle-class constituency.

The Republicans' dilemma is that they have campaigned against Big Government, blaming it for assorted ills, but Big Government, for all practical purposes, is indestructible. Sure, a little piece can be chipped away here and there. But the basic pillars of government activity -- defense, Social Security, environmental protection -- represent a broad social consensus not to be undone.

The peculiar rhetoric of the campaign portrays "government" as some sort of independent entity floating free of the popular will. This, of course, is nonsense.

To be sure, legions of bureaucrats seem to live by rules and customs understood only by other bureaucrats. But the perceptible instances of bureaucratic isolation cannot obscure the more central reality: that government represents the symbol and repository of mass expectations, inconsistencies and all.

This marks a major change in our political culture. Politicians need scapegoats, if only as an emotional outlet. Franklin D. Roosevelt, considerably aided by the belief that the Depression originated in the abuse of private power, eagerly cast Big Business in this role. With modifications, the Democrats continued the tradition for the next 35 years.

At any juncture, government could mend the imperfection of profit-seeking private firms and unfettered markets. But, over time, this orientation was bound to self-destruct. Slowly, it dawned on people that Big Business was no longer the central institution of national life.

Government had assumed that position, but this left politics in a state of masochistic confusion. To tap popular discontent, politicians ran against government; but victory meant they became the scapegoat -- and the next victim.

Nowhere are expectations and realities more at odds than in the management of the economy. Such as it is, the Republican strategy of broad tax cuts, reduced spending and tight monetary control contains inherent limitations and contradictions.

Today, government spending consists heavily of the following categories: 25 percent for defense; 25 percent to 30 for programs for the elderly, including Social Security, government pensions and Medicare; and 12 percent to 13 percent for interest on government debt. The number of elderly is rising, and Reagan has committed himself to a 5 percent increase in "real" (after inflation) defense spending. Given these pressures for higher spending, Reagan will have to make substantial cuts simply to hold government outlays steady as a proportion of the nation's output.

Tax cuts? The centerpiece of the Republican platform, the Kemp-Roth bill, promises a 30 percent reduction in tax rates over three years. But, as Reagan has admitted, this may do little more than offset the tax increase that automatically occurs when inflation (raising incomes but not purchasing power) pushes people into higher tax brackets.

As for tight money policies, they reflect mainstream thinking. By this notion, if the Federal Reserve accommodates rising wage settlements, prices and government spending by pumping out more and more money, it simply lays the groundwork for a further acceleration of inflation: that is, from the current 9 percent to 11 percent to 12 percent to 15 percent. But the underlying inflationary momentum makes the cost of this policy high interest rates and a stagnant economy. Already, some Republicans are grumbling loudly.

The conventional notion of politics is that when you win, you reward your friends and punish your opponents. This is how you build faithful constituencies. The Democrats practiced this brand of politics for almost half a century as they sought to maintain the Roosevelt coalition of labor, ethnic voters and social liberals. But if the Republicans attempt to embrace this approach, they soon will find themselves overwhelmed.

The easiest way to understand the election returns is in income terms: Those families with incomes over $15,000 voted overwhelmingly for Reagan, and those under $15,000 voted heavily for Carter. Middle-class voters want the sense of stability implicit in lower inflation, but that's not all they want. Only a feeble imagination can fail to see the various favors, mostly tax breaks, that may be urged upon Reagan for middle-class constituencies: homeowners, farmers, small businesses and parents of college students.

Succumbing to these pressures simply would compound the strains on Reagan's economic policy and, ultimately, complicate the central problem of governing. It would further erode government revenues (making general tax relief the more elusive) and telegraph the message that economic success is to be won less by individual exertion than by clever politicking. And these actions would do little, if anything, to retard the economy's inflationary drift.

Inflation is, in the end, a middle-class phenomenon, one in which no one feels responsible but everyone feels a victim. The universal desire to stay even keeps it going and, in the end, makes it more difficult for everyone to get ahead.

The Republicans cannot fight inflation simply by cutting spending for the poor, because spending for the poor doesn't constitute enough of total spending. Trying to do so would not only be futile but would repudiate the best in the conservative tradition.

If Reagan's economic job is to cool the expectations that propel inflation, his more fundamental job is to evolve a philosophy of governing that reconciles the new social and political realities of Big Government with the old conservative ideals of personal responsibility and decentralized power. At best this is a difficult marriage, and it may be impossible.