Historians at the Sorbonne once fiercely disputed which of the French Revolution's twists and turns represented the core moment of that upheaval and its voluminous aftermath. The storming of the Bastille, the Reign of Terror, Bonaparte's coup d'etat and other moments each had their champions.

The obvious answer emerged as a consensus view only in recent years: The revolution had to be taken en bloc. It had to be viewed as a panoramic whole to understand its meaning and decisive influence on modern France.

That is ultimately how Americans will come to view the roller coaster ride on which history embarked them on Sept. 11, 2001. Do we glimpse what American national character has become in those appalling photographs from Abu Ghraib prison, as al-Jazeera's propagandists claim?

Or in the secret government memos that would whittle away at the definition of torture? Or, more comfortably, in the cogent and principled Supreme Court decisions that slapped down John Ashcroft's effort to deny detainees the right to counsel and a judicial hearing?

Sept. 11 may have changed everything but the Constitution, the court's majority seemed to be saying on June 28 in ruling that even Yaser Esam Hamdi, a U.S. citizen captured on a battlefield in Afghanistan, must have his day in court. So must the approximately 600 terrorism suspects held at the Guantanamo Bay naval base.

These developments provide only pieces of the still unsettled whole. National character -- the ingrained habits, shared sense of destiny and implicit agreement on the rules of what Justice Sandra Day O'Connor, writing the Hamdi opinion, wonderfully called "the privilege that is American citizenship" -- is forged or altered in the crucible of emergency. But it settles only when the emergency is perceived to have eased enough to permit reflections on what we will now accept as "normal."

The lengthening period since Sept. 11 has created a sense of virtual emergency. President Bush mobilized the armed forces to fight the war on terrorism.

But he has not mobilized society on a similar war footing at home. He has not conscripted soldiers or factories and other national economic resources as most wartime presidents have. He leaves the impression that the nation does not need to devote all its resources to confronting an immediate, specific threat of destruction, whatever his rhetoric.

The Supreme Court's decisions hint at this reality: The danger that al Qaeda and terrorism seemed to pose to Americans looks different today than it did in the autumn of 2001, as the administration staged roundups of thousands of young Muslim immigrants and fought against establishing any recognizable judicial routine for the Guantanamo detainees.

The court halted an effort to evade the obvious: that what is judicially reasonable in one circumstance may not be in another, especially as time goes by. The government does have a "legitimate concern" in detaining enemy fighters for the duration of a conflict. But what happens to those fighters once they are incarcerated away from the battlefield cannot be exclusively decided by the president and his aides. That would unacceptably "condense power into a single branch of government," the majority held.

This movement toward a virtual normality to replace a mental state of emergency is at the mercy of any al Qaeda suicide squad. But for the moment, a new, still-shifting balance is being struck between the United States' commitment to individual liberties and its modern security needs. The Supreme Court pointed the way by demanding that judges hear the terrorism cases -- but also that they grant the government significant procedural leeway in dealing with terrorism suspects. Two important recent books on ethics and the use of force also illustrate how that balance is being rethought.

"Even in times of real danger, political authorities have to prove the case that abridgments of rights are justified," writes Michael Ignatieff in "The Lesser Evil," anticipating the Bush administration's fundamental mistake of maintaining obsessive secrecy about its actions and policies on detainees, the effort to redefine torture and so much more.

Only adversarial public review within a democracy's legislative and judicial institutions can prevent the abuse and entrenchment of executive powers that Harvard's Ignatieff acknowledges are justified in a state of emergency. Even then, "getting risk and response into balance is easy only in hindsight."

"Arguing About War" by Michael Walzer of Princeton is more theoretical. But its discussion of the evolving standards for humanitarian intervention in sovereign states, and of the morality of extended military occupation, is also a good guide through the political and moral thickets of the American summer of 2004.