Politically, nothing is more fun than being in the minority in a legislative body. Sure, the majority makes policy, dispenses patronage and assigns parking spaces. But the majority also has to accept responsibility for what happens, something from which the legislative minority can flee. If you and I, together, constitute the minority on our local seven-member school board, then we can taunt the governing majority by -- mischievously and irresponsibly -- moving to double all teacher salaries while cutting everybody's property taxes in half. The majority is then required to declare "responsibly" -- while you and I snicker -- that teachers' salaries will be frozen and property taxes increased.

After 30 years without a majority or the responsibility that goes with it, Republicans took control of the Senate in 1981 and have maintained it since. The current majority leader, Sen. Robert Dole (R-Kan.), like Howard Baker before him, made the decision that he would control the Senate with Republican votes and that only after he had failed to obtain the necessary votes from his side of the aisle would he seek Democratic votes.

Earlier this year, in an act of collective political courage and responsibility, Senate Republicans voted for a deficit-reduction package that featured a one-year freeze on cost-of-living increases for Social Security recipients. Wallowing in their own minority status, Democrats in and out of the Senate predictably demagogued the issue.

But this past week, the Republican president rewarded his Senate majority for its earlier show of guts on the deficit by agreeing to drop any freeze on Social Security. He thereby hung out to dry the 18 GOP senators up for reelection next year who had voted for the deficit-reduction package.

The week's casualty list is a long one.

Bob Dole: The White House decision, which now isolates Senate Republicans as the only elected politicians "heartless" enough to freeze Social Security, suggests that either Dole did not object forcefully enough or the White House simply ignored him. Neither interpretation strengthens Dole's position in the Senate.

Senate Republican unity: One astute congressional Democrat who has openly envied Dole's ability to forge a nervous majority into "a cohesive, disciplined unit" confidently predicts that Senate Republicans will break up "into a crowd of independent political contractors." The model that 1986 GOP incumbents will now follow is that of administration critic and maverick, Sen. Charles Grassley of Iowa, whose reelection has been all but conceded by Democrats. The president's popularity, proving that Bitburg was only a brief blip, has returned to its pristine levels. So Senate GOP incumbents, who will still welcome Reagan politically into their states, will be more cautious in following the president's lead on policy.

House-Senate Republican tension: Not a single Republican member of the House has ever served in the majority. The minority mindset, which encourages guerrilla ambushes to bedevil the chamber's Democratic majority, is strong among House GOP members. In 1982, with the nation suffering the deepest recession since the Great Depression, the GOP had its life further complicated by Reagan administration bungling on suggested cuts in Social Security. That election year, the political suffering from Social Security and unemployment was borne entirely at the federal level by House Republicans, who lost 26 seats while the GOP Senate dodged the bullet.

Republican confidence in the White House: The president's switch was blamed, by one Republican with close Reagan ties, on "those technocrats in the White House who've never been through a campaign." Wistfully, GOP managers speak of the departed Jim Baker, who appreciated the congressional reaction to any policy move because "you always have to go back to the Hill tomorrow."

Certainly the president did appear to cave on Social Security before any public sense of crisis had developed over the budget impasse. If the White House had determined that a change on Social Security was necessary, then the political script would have called for the president to be "persuaded" by the Senate Republicans who, after maturely and responsibly dealing with the issue, had "concluded" that the COLA freeze might not be necessary. At the White House, it was amateur hour.

The Senate Republicans painfully learned what the Senate Democrats and House Republicans know: just how much fun it is to be in the legislative minority.