This is the rule laid down to every beginning journalist: Dog bites man? No story. Man bites dog? That's a story. It's for this most basic of all reasons that "Man of the House," Tip O'Neill's breezy autobiography, is such fun to read. In it, the former speaker of the House finally bites back.

Take syndicated columnists Rowland Evans and Robert Novak. O'Neill writes that shortly after he became House majority leader in 1972, the two paid him a visit: "They had the gall and temerity to offer me a deal: If I kept them informed as to what was happening in Congress and the White House, they would see to it that I would receive great press notices. . . . I kicked them right out of my office." (Evans calls O'Neill's story "an outrageous, wretched libel.")

Or take Ronald Reagan. O'Neill gives the president his due as a politician, public speaker and national leader. "But I've known every president since Harry Truman, and there's no question in my mind that Ronald Reagan was the worst," O'Neill writes. He says, "Most of the time he {Reagan} was an actor reading lines, who didn't understand his own programs. I hate to say it about such an agreeable man, but it was sinful that Ronald Reagan ever became president."

And what, aside from political differences, so exercised O'Neill about Reagan? The former speaker provides some specifics. He tells of the time in 1983 when Secretary of State George Shultz called him at 7 a.m. to say the Soviets had downed a Korean airliner. "What does the President think about this?" O'Neill asked. Shultz said Reagan was still asleep. "You've got to be kidding," said O'Neill. "You mean you're calling me even before you've notified the President?" Shultz said, "We'll tell him when he wakes up."

O'Neill tells of a White House meeting called to inform the congressional leadership that the United States was about to invade Grenada. A contingent of Marines was also in Lebanon at the time, and the president apparently had them in mind when he interrupted the briefing. He told of a speech describing the scene in 1946 when American troops left the Philippines to the grateful cheers of Filipinos. O'Neill was puzzled by this digression, but later the president took him aside to explain: "I can see the day . . . when the Lebanese will be standing at the shore, waving and cheering our Marines when they depart." The Marines did not depart, they retreated. And there were no cheers.

O'Neill has plenty of these stories. He writes about a president who reads even casual remarks off index cards, who is inattentive at meetings and who sets policy by anecdote. He relates a Reagan story about a welfare recipient who calls around for a job but quickly hangs up when one is offered. "These people don't want to work," the president told a meeting at which O'Neill was present. "Don't give me that crap," O'Neill exploded, and then laid into the president until an appalled Sen. Alan Simpson (R-Wyo.) intervened. "This is awful," he said. "You fellows are always bickering."

O'Neill's is not the standard Washington memoir. While he remains uncritical of his friends, he does not hesitate to settle some scores. The all-but-deified Robert F. Kennedy is described as a ruthless brat. The Kennedys in general are treated kindly (especially John F. Kennedy), but O'Neill does not gloss over how they used their money to buy political success. He has a lingering respect for Jimmy Carter's intellect, but not for his political abilities, and he has nothing but contempt for most of Carter's aides, especially Hamilton Jordan.

The book has some touching moments. Here is Rep. Peter Rodino (D-N.J.), chairman of the Judiciary Committee during Watergate, listening to Richard Nixon on tape denigrating Italians. "They're not like us," said Nixon. "They smell different, they look different, they act different. The trouble is, you can't find one that's honest." Rodino, anguished, never made that tape public. He wanted the case against Nixon to be decided on its legal merits.

The forthcoming "Man of the House," written with the assistance of William Novak, is pure Tip. It is anecdotal, earthy, unpretentious and casual. For the sake of a good story, remarks are quoted verbatim when they appear actually to be paraphrases. With few exceptions, politicians are judged on their bonhomie and performance in the House but not on their policies.

But the real Tip O'Neill comes through. He is a man of the old school whose political ideology amounted to one word: fairness. He left Washington on his own terms and has written a swell book to match. For years, O'Neill was the speaker who wouldn't bark. Now we know he can bite.