WAS ABSCAM JUSTIFIED? Should FBI men dress up as Arab sheiks and offer $50,000 bribes to members of Congress who may have conducted themselves honorably up to that moment?

Probably no more troublesome issue has arisen in the area of law enforcement and public policy in recent years. In dissecting ABSCAM, Sissela Bok examines the question, as she does others, with cool precision and suggests balanced, sensible answers. No, she says, members of Congress "have no special claim to be exempt from scrutiny," and if anything, they should have an extra measure of accountability. They could have said no. But that conclusion, she argues, hardly justifies the "elaborate deceits" of ABSCAM.

Secrecy and deception, Bok suggests, will inevitably be used by police agencies not only to investigate crimes but to generate crime, as occurred in ABSCAM. And she asks --pointedly--whether a democratic society can tolerate "the tools of secret police networks--secrecy, deceit, and provocation" and still remain confident that it can control the power of its own government.

How can ABSCAM-type methods be legitimate, "when aimed at persons who may not be guilty of any crime or even thinking of committing one? Might these persons not be unfairly drawn into crime by the police? And is this not contrary to all that the government and the police should aim for?" Moreover, Bok warns, when the government resorts to "disreputable" methods, it may "erase the difference the public sees between the police and the lawbreakers they are supposed to be combating."

There is an additional and perhaps crucial point that is closely related to Bok's argument against unregulated government undercover operations. ABSCAM, whatever its origins or intent, has had the effect of an intimidating signal to Congress by the FBI, whose budget the legislators control. During the 1970s Congress investigated the FBI and other intelligence agencies more vigorously than it had ever done in the past. Might Congress hesitate to do so again?

The FBI's "Arab scam" is only one of dozens of questions about secrecy in all of its aspects--personal and public--considered by Sissela Bok, a philosopher and member of the Harvard faculty, in Secrets, a book that complements her earlier work, Lying. She ranges wide on her latest journey, from an examination of secret societies and the obligations of confidentiality imposed on psychiatrists and lawyers, to the mores of government whistleblowers and investigative reporters. Along the way, she stops to consider whether Daniel Ellsberg was justified in leaking the Pentagon Papers, whether engineers on San Francisco's BART were right to warn publicly of safety dangers, and whether social scientists are warranted in using intrusive and deceptive methods to study children or primitive tribes. One does not have to agree with all of her conclusions to respect the intellectual rigor of her arguments or her moral courage in addressing questions that do not, as a rule, lend themselves to easy answers.

Bok defines secrecy as "intentional concealment" but distinguishes it from privacy ("A private garden need not be a secret garden . . ."). Not all things secret are bad, she points out; jury deliberations could hardly be open, and imagine "the game of chess without secrecy on the part of the players." On the other hand, Bok argues, most bad things "seek out secrecy."

Government secrecy, as Bok rightly perceives, imposes a special burden because it undermines the "informed choice by the electorate" that is the basis of democracy. "Every government," Bok writes, "has an interest in concealment; every public, in greater access to information." This conflict warps even those presidents who are initially, at least, on the side of the angels. "How many leaders have not come into office determined to work for more open government, only to end by fretting over leaks, seeking new, safer ways to classify documents, questioning the loyalty of outspoken subordinates."

And the invocations of secrecy and "national security" sometimes have an opposite effect from that intended. The intense secrecy surrounding President Carter's rescue mission to free the hostages in Iran contributed to the failure of that operation. Bok quotes the Joint Chiefs of Staff review group on the point: "Many things that, in the opinion of the review group, could have been done to enhance mission success were not done because of OPSEC (Operations Security) considerations."

In Washington, officials decry news leaks--Richard Nixon's paranoia over leaks led him to create the Plumbers, eventually resulting in his resignation in disgrace--but the same officials leak "selectively to further their own policies." As a result, "the leak . . . has become an important tool of governing."

Secrecy did not begin in America with the rubber stamps and classification categories of the postwar, national-security state. As Bok notes, the Constitution was framed in complete secrecy; ordinary citizens were excluded. Madison argued that without such secrecy, the Constitution would never have been framed. But Jefferson complained of an "abominable . . . precedent."

Secrets is highly rewarding, but not light, reading. At times the book seems almost quixotic, as when Bok attempts to differentiate between acceptable and unacceptable gossip. "It is wrong," she remonstrates, ". . . to reveal in gossip what one has promised to keep secret." Well, yes.

Attempting to set moral standards for gossip is like trying to hold Bible classes in a bordello. It can be done, but it's awfully difficult. The law of gossip is that the juicier the morsel,,the more likely it is to be passed along. The author's typology of acceptable gossip is not likely to have much impact along the back fences of America. One cannot really define moral gossip because gossiping is essentially an immoral activity. That is what makes it so much fun.

But Sissela Bok has a razor-sharp mind that slices away cant and pretension and fuzzy thinking like a machete laying low whole jungles of intellectual underbrush. She shines her light in dark places, illuminating the secrets of secrecy itself, while recognizing "the mysterious and the unfathomable in human beings," aware that "no one can be known in entirety, neither from within nor from without." We are secret, even from ourselves.