The Founding Fathers are growling in their graves. The Senate is now debating campaign-finance "reform": a respectable-sounding idea that's a fraud. Campaign reform would cure problems that don't exist with solutions that would restrict free speech, smother elections in bureaucratic rules and hurt candidates' chances of beating incumbents. It's an odd way to celebrate the Constitution's 200th birthday.

Blame that on Fred Wertheimer of Common Cause. His crusade for reform -- campaign-spending restrictions and public financing -- is built on half-truths. He says that campaign contributions of "special interests" have corrupted politics. They haven't. The Founding Fathers knew that special interests were inevitable. Their government of checks and balances requires compromise; competing groups check each other. The system isn't perfect, but it curbs the undue influence of campaign contributors.

Wertheimer is a genius at obscuring this. He harps on the huge rise in congressional campaign spending -- up from $195 million in 1978 to $450 million in 1986 -- and its simplest implication: that because congressmen need more money, they're more beholden to donors. The obvious answer is to limit dependence on the donors. The logic fits popular prejudices about special interests, and most editorialists and journalists accept Common Cause's claims uncritically. They shouldn't.

For starters, money doesn't determine who wins elections. Winning candidates are often outspent. In last year's Senate election, says political scientist Michael Malbin, six of the seven Democrats who ousted incumbent Republicans were outspent by an average of about 75 percent. There are too many other influences to make money decisive: the economy, party loyalties, personalities, issues, national mood. The 1986 election results, Brooks Jackson of The Wall Street Journal wrote later, suggested "that much ... . was spent with little practical effect."

Paradoxically, campaign reform could make it tougher for challengers to unseat incumbents. If money doesn't settle elections, serious challengers need adequate minimums to gain name recognition and project campaign themes. It's these threshold amounts that campaign reform threatens. The spending limits in the bill before the Senate are below what five of the winning Senate Democratic challengers spent. In North Carolina, Terry Sanford spent $4.17 million to beat former senator James T. Broyhill. The bill would have allowed Sanford $2.95 million.

No one is smart enough to set "correct" spending limits based on population or anything else. States and congressional districts differ radically in political characteristics. California races require lots of media spending. That's less true in Chicago. Spending in hotly contested races is typically higher than average. Because Congress -- that is, incumbents -- would control spending limits, the bias would be against challengers.

Likewise, Wertheimer's assertion that campaign contributions corrupt the legislative process is similarly weak. You hear lots of talk about the dangers of political action committees (PACs). What you don't hear is: PACs remain a minority of all contributions. In 1986 they were 21 percent for the Senate (up from 17 percent in 1984) and 34 percent for the House (level with 1984). The diversity of the 4,157 PACs dilutes their power. There are business PACs, labor PACs, proabortion PACs, antiabortion PACs, importer PACs and protectionist PACs. Contributions are fairly evenly split between Democrats ($74.6 million in 1986) and Republicans ($57.5 million).

PACs give heavily to senior, powerful congressmen, who are politically secure and not easily intimidated. According to Common Cause, Democratic Rep. Augustus Hawkins of California is the most dependent on PAC contributions (92 percent). First elected in 1962, he won last year with 85 percent of the vote.

Of course special interests mob Congress. That's democracy. One person's special interest is another's crusade or livelihood. To be influential, people organize. As government's powers have grown, so has lobbying by affected groups: old people, farmers, doctors, teachers. The list runs on. But PACs are only a minor influence on voting. Political scientist Frank Sorauf of the University of Minnesota reports that in 1984 the average PAC contribution to House incumbents was less than one-third of 1 percent of the average congressman's total receipts. Congressmen vote according to their political views, constituents' interests, party wishes and -- yes -- their consciences. Special interests were supposed to block tax reform. They didn't.

About half the rise in campaign spending since 1978 reflects inflation. Much of the rest stems from the emergence of younger politicians who use expensive campaign consultants, television and direct mail. In 1984 Democratic House Speaker Thomas P. O'Neill Jr. of Massachusetts spent $213,000 winning reelection. In 1986 Democrat Joseph P. Kennedy II spent $1.8 million to win the same seat. But the expense of modern communications makes it no less vital for free speech.

That's why the Supreme Court held in 1976 that mandatory campaign-spending limits on candidates violate the First Amendment. Public financing of election spending aims to make "voluntary" limits more acceptable. But even if voluntary limits on candidates were enacted, the problem of "independent spending" remains: if I want to buy TV time to support Joe Blow, the Supreme Court says that's my right. Candidate spending limits would prompt special interests to raise independent spending. The Senate bill tries to deter this by subsidizing responses: my $10,000 praising Joe Blow would entitle his opponent to $10,000 of public money to answer me.

Suppose this were judged constitutional (unlikely), what's the point? In our diverse society, one role of politics is to allow the venting of different opinions and pent-up frustrations. Groups need to feel they can express themselves and participate without colliding with obtuse rules intended to shut them out. Our politics is open and freewheeling. Its occasional excesses are preferable to arbitrary restraints. Wertheimer's brand of reform is misconceived. The Senate would dignify the Founding Fathers by rejecting it.