One thing is clear: this election is Ronald Reagan's to lose. The advantages of incumbency are undeniable, but Jimmy Carter has already transmuted them into handicaps: his every act is routinely interpreted by pundits and men in the street as politically motivated. No ingredient can turn a stew into a souffle, and no possible act could now render the Carter administration coherent.

After flirting dangerously with Gerald Ford, Reagan turned to a running mate who will support, not swamp, the theme of his campaign: to make America productive again. Ford might have been a disaster, if not for the campaign, then for the Reagan administration, given the stiff terms he demanded. George Bush may be bland, but pliability is a mate's virtue, and most of the party and the nation can live with him. Better yet, perhaps, would have been Jack Kemp, a far better politician than quarterback, who has discovered, developed and all but patented the new economics on which the Republicans are pinning their hopes.

From Kemp, Reagan has learned to turn the tables on the Democrats. Since 1932, the Republicans have been thrown off balance by their opponents' pork-barrel politics, and it has been their role to play the naysayers, occassionally stepping in to clean up after Democratic profligacy. Now they have recovered the initiative, forcing the Democrats to advocate austerity.

As Kemp put it in one of the convention's most stiring (and underreported) speeches, "when you subsidize something, you get more of it. In America today, we are taxing work, saving, investment, enterprise and excellence, as never before. And we are subsidizing non-work, consumption, debt, leisure and mediocrity. Is it any surprise that we are getting less of the one and more of the other?"

Kemp, a superb campaigner, may be the Republicans' hope of the future. Reagan, an even better campaigner, will do for now. His acceptance speech began by reaching out, as generously as his principles permit, to disgruntled feminists. He aims to build a moderate consensus around a strong conservative principle: that any benefits a government can confer, including strong defense, depend on the vitality of the private sector.

In the past, the conservative flaw has been sectarianism, a repellent exclusivity. The 1964 Goldwater campaign seemed, at times, to regard the entire electorate with suspicion, as a wicked people that joined labor unions and voted for mounting doses of redistribution.

Reagan's demeanor is wholly different. He talks to the public as if he trusts it. Unlike Jimmy Carter, he seems neither to moralize nor to manipulate. His convention was marked by gestures to women, blacks and (most notably) the working people whom Republicans used to fear. His concern was expansive and inclusive: "We're not going to leave anyone behind."

In fact, Reagan articulated what might be termed the exploitation theory of government: it produces nothing, but can only spend "money earned by working men and women." That's a hard shot to the Democratic solar plexus: it blames the Democratic Party for the hardships of its traditional followers. The theme of "workers betrayed by this administration" will be heard often this fall.

The theory behind the Reagan campaign is that of economist Arthur Laffer, who has tried to pinpoint the optimum rate of taxation. For all the controversy he has generated, Laffer's point is basically simple. If you tax not at all, you get no tax revenues; if you tax at 100 percent, you also get no tax revenues, because people quit producing. The trick is to locate the rate at which people produce a surplus that will not be dampened by giving the state a healthy share.

There can be much debate about this, but the common sense of the country is that present tax rates (including the disincentive of inflation) are killing off the goose that used to lay golden eggs. We pay to much, and about all we have to show for it is the grim prospect of four more years of Jimmy Carter. It will be Jimmy Carter's job to persuade the nation that Ronald Reagan represents an even grimmer prospect than himself, if that's possible.