YOU MAY HAVE noticed that two quite different theories of government are at war over the country's energy policy. President Carter's energy planners are mostly economists, who think in terms of prices, costs and incentives. But congressmen are mainly lawyers, professional or otherwise, and they think in terms of regulations and legal requirements. Economists worry a lot about efficiency. Lawyers worry more about equality. You can see this combat proceeding in the interesting issue of home insulation.

The President proposes tax credits for people who insulate their houses. He relies on that, and a rising price of fuel, to exert a firm and steady pressure on the homeowner to move in the direction of the national interest. But to a lot of congressmen, leaving things to self-interest seems vaguely immoral - and talking about raising prices is forbidden.

That's why the President's plan for a tax credit survived only by the ominously thin margin of one vote in the first test this week in the House Ways and Means Committee. The main current of congressional opinion is represented, in contrast, by the House energy subcommittee's vote to require owners by law to insulate houses before selling them.

The energy subcommittee acknowledged that there will have to be exceptions for poor people, and exceptions for houses about to be torn down, and exceptions for those that are goind to be renovated. But harder questions lie beyond. Is it fair to make people in Maine pay more for insulation than people in Florida? What about houses where insulation would require major construction - those with no access to roof space, or with no hollow space in the walls? What's an adequate storm window? All these questions and hundreds more will be answered in the fat book of regulations to be carried by the insulation inspector who goes through your house, ruler in hand, before you can put it on the market.

It's best not to be doctrinaire in these matters. There are certainly cases where a well-crafted regulation is the shortest distance between two points. But home insulation isn't one of them. Congress is now on the verge of making an expensive mistake. If it decrees insulation without doing anything about prices, this new law will simply make it cheaper for people to waste fuel by overheating their houses. Congress is in the process of making the same mistake, incidentally, in regard to automobiles. By law it requires the companies to produce cars that get more miles to the gallon, but it refuses to hear of a gasoline tax. That merely makes it cheaper to drive long distances and, if this non-policy persists, the average American will be driving several thousand miles farther each year by the mid-1980s than today.

Perhaps the economists' advice about prices and taxes seems cold and heartless. But gradual and steady price increases - we emphasize the words gradual and steady - would be a great deal less destructive than further fuel shortages like the trouble with natural gas last winter. The regulatory tradition has, of course, its own answer to a shortage: rationing, with all of the tangled apparatus of inspection, policing and poking into people's lives that it requires. That's one aspect of energy policy that the congressional committees evidently prefer not to think about.