The public debate about George Bush and the Iran-contra affair, which took a new turn in his prime-time TV confrontation with Dan Rather, is being hindered by confusion over three separate issues.

Is the issue, as many would have it, whether Bush has whipped ''the wimp'' issue by standing up to and talking down America's most-watched anchorman?

Is it, as Bush has tried to say from the beginning, whether he behaved in a principled way through the original decision-making and told the truth in the later investigations?

Or is it a question of the judgment he exercised -- or failed to exercise -- in his role as the No. 2 official of the federal government?

The answers, in my opinion, are, respectively, no, no and yes. And sorting it out that way may help dispel at least some of the confusion.

The issue is not Bush's ''wimpiness,'' because that issue was a phony from the start. It rested on his prep-school vocabulary, his almost too well tailored clothes and much too youthful appearance. Most of all, it came from the incident of the Nashua debate in 1980, when Bush appeared to choke in the face of Ronald Reagan's last-minute effort to include four other Republican candidates in the forum.

The Nashua impression is contradicted not only by Bush's demonstrated courage as a young naval aviator but by the tenacity with which he has pursued his political goals often against heavy odds, over the past quarter-century. A man who is a ''wimp'' does not hurl himself twice against the favored incumbent Democratic senator in Texas. Nor does he seek the presidential nomination as Bush did in 1980 when his only election victories had come in two House races more than a decade earlier.

Anyone who was around Bush when his friend and campaign manager, Jim Baker, was trying to get him to concede the inevitability of Reagan's nomination halfway through the spring primaries in 1980 would testify that the man is no quitter. Bush was the last to give up the fight.

In practically every debate this campaign, he has punched and counterpunched effectively, so his standing up to Rather's belligerent questioning and frequent interruptions should not have been a surprise.

Nor frankly does it prove much. Many a politician has proved he can beat the press, especially on TV. But that hardly qualifies him to be president. Remember Spiro Agnew, no slouch as a press basher?

Nor is it an adequate presidential credential to insist, as Bush does, that he has acted on principle and been completely honest in discussing the Iran-contra affair. In his first Iran-contra interview last August, after the televised Senate-House hearings ended, he told me with some satisfaction, ''I think people may now understand I was telling the truth. . . . The question of telling the truth is awfully important to me. It's sacrosanct. And I found it troubling when people thought I was lying.''

Those who are scholars of Iran-contra (as I am not) will tell you that while all the official investigations have left Bush unscathed, he has changed what they regard as significant details of his story. On the basis of more than 20 years of dealing with him, my strong presumption is that he is telling the truth, and that any contradictions result from the human tendency to gloss over or push from our memory moments or incidents that make us think badly of ourselves.

It is also completely in character for Bush to insist on ''the principle'' of keeping confidential his advice to the president. As Fred Barnes has pointed out in The New Republic, that was one of the "rules'' Walter Mondale gave Bush after the 1980 election, when they discussed how to be a success as vice president.

Bush is a stickler on ''rules.'' The main reason he got into trouble in Nashua was his fixation on the "agreement'' he had made with the Nashua Telegraph, the debate sponsor, to go one-on-one with Reagan. Bush still believes he did the principled thing by adhering to that agreement, and he insists on keeping silent on his advice to the president out of the same principle.

But discussions of principle don't take you much farther than the ''wimp question'' does. The question voters must resolve about Bush is one of judgment and of action: Can he assess a situation realistically and act effectively?

In the Iran-contra affair, the evidence clearly indicates Bush did not. He has said repeatedly that he did not figure out it was an arms-for-hostage deal. Nor, he says, did he see it as a contradiction of the antiterrorism policy Reagan had asked him to develop for the administration. He says he did not pick up the fact that the secretary of state and the secretary of defense had strong and vehemently stated objections to the arms sales. He says he expressed some reservations of his own -- about the role of the Israelis and the risk of exposure -- but clearly his ''reservations'' had no impact on the president's decisions.

It is, in short, a record of obtuseness and futility.

Now, as Bush reminded Rather, it is also one episode in seven years as vice president and almost 25 years in public life -- so it deserves to be put into context. But in itself, it raises disquieting questions.