Readdressing the most explosive controversy of his tenure as University president, Lawrence H. Summers said yesterday that his January 2005 speech on women in science was, “in retrospect, an act of spectacular imprudence.”

He appeared at the final meeting of “Morality and Taboo,” a course inspired by the furor over Summers’ presidency that led to his resignation last year. The class has examined why some concepts and ideas are considered improper in certain public arenas.

“I can’t for the life of me figure out why anything in my past could cause me to be invited to an event like this,” Summers quipped as he was introduced by the course’s two professors, Johnstone Professor of Psychology Steven Pinker and Frankfurter Professor of Law Alan M. Dershowitz.

“Well, maybe that was the problem,” Dershowitz quickly replied.

For the two course heads, Summers is a martyr of taboo within the ivory tower. They publicly defended Summers after he suggested, at an economics conference nearly 28 months ago, that “intrinsic aptitude” could partially account for the dearth of female scientists at elite universities. When the remarks became public, he faced a wave of condemnation at Harvard and across the country.

“All kinds of girls all over the world were reading that the president of Harvard believes that they can’t do math,” Summers recalled yesterday. He said that his position at the University’s helm should have kept him from acting as an “intellectual provocateur.”

Still, while he repeatedly called his speech a mistake, Summers also criticized some of the ensuing reaction and media coverage.

“I think one can wish that these things can be discussed more openly as hypotheses by people with an understanding of statistics and an understanding of the relevant behavioral biology, rather than be oversimplified and demonized,” he said.

Summers has generally declined to reexamine the contents of his speech since he repeatedly apologized for it two years ago. Yesterday, however, he added one more hypothesis to explain the under-representation of female scientists.

In a brief aside, Summers compared girls and boys who earn a perfect score on their math SATs. The girls, he said, are more likely to score higher on the verbal portion of the test.

Summers then asked rhetorically whether it should be “shocking or disturbing” that those girls choose to enter fields broader than math, given their “superior verbal abilities.”

Reflecting on other “taboo” topics he broached in five years at Harvard’s helm, Summers strongly defended his September 2002 speech at Memorial Church, which called professors who advocated divestment from Israel “anti-Semitic in their effect if not in their intent.”

Some professors who favored divestment said the speech prevented others from stating their views on the topic, for fear of being labeled anti-Semitic.

“I was extremely careful not to criticize their intent in what they were proposing,” Summers said yesterday. He added, “I don’t find it plausible that anyone felt that they couldn’t speak freely on the issue.”

But while taboo was the topic of the day, Summers said “the end of my presidency” was due to more than his impolitic remarks.

“Some of it undoubtedly had to do with the issues we’re discussing,” he said, “but part of it also had to do with my conviction to push the faculty into places that they were less willing to go.”

—Staff writer Zachary M. Seward can be reached at seward@fas.harvard.edu.