Rubenstein argued the relative magnitude of injustices should not be considered.

“Getting raped is worse than getting mugged,” he said facetiously. “But getting mugged is still bad.”

He said Parker’s view of torture as simply the stimulation of normal emotions ignores its brutality.

“Torture is off the end of the line,” he said.

Allowing any exceptions to the government’s strict condemnation of torture will contradict the principles of the nation’s legal system, Rubenstein said.

“To say that anything goes in protecting citizens seems to abandon law altogether,” he said.

But Parker questioned the slippery slope of injustice that Rubenstein asserted, suggesting that the government should be able to maintain its self-control.

“Why should we assume that people trying to get information [through torture] will drive on and on and on?” he asked.

—Staff writer Nathan J. Heller can be reached at heller@fas.harvard.edu.