Accepting the Nobel Peace Prize in 1995, the anti-nuclear campaigner Joseph Rotblat concluded with words that he had repeated and lived by in one form or another for more than half a century: “Above all, remember your humanity.”

To Rotblat, who died Aug. 31 in London at age 96, the military, diplomatic, and political questions surrounding nuclear weapons paled besides the ethical ones.

The current notions of nuclear deterrence are unacceptable on moral grounds,” he wrote in 2002. “By acquiescing in this policy, not only the leaders but each of us is taking part in a gamble in which the survival of human civilization is at stake. We rest the security of the world on a balance of terror. In the long run, this is bound to erode the ethical basis of civilization.”

Rotblat fought such thinking for more than six decades. During the 1940s, he became the only scientist to leave the Manhattan Project for moral reasons. He had supported the project to build the first atomic weapons when it was believed that Nazi Germany might first acquire a nuclear weapons capability. When it was clear that the German danger had passed, however, he no longer wanted to be associated with the effort and was dismayed by the bombings of Hiroshima and Nagasaki.

Several years later, Rotblat befriended the British philosopher Bertrand Russell. Russell was interested in Rotblat’s research on the biological effects of radiation based on his examination of the fallout from the 1954 U.S. hydrogen bomb test at Bikini Atoll. Soon thereafter, Russell decided to seek Albert Einstein’s signature on a letter with seven other Nobel laureates that would become known as the Russell-Einstein manifesto. Einstein agreed to do so; it was his last message before his death

“Here then is the problem which we present to you, stark and dreadful and inescapable: shall we put an end to the human race; or shall mankind renounce war?” the signatories asked in that famed 1955 document.

The Russell-Einstein letter would serve as Rotblat’s personal manifesto in the years to come. Two years later, he would help to found the Pugwash Conferences on Science and World Affairs. These conferences have brought together thousands of influential scholars and public figures concerned with reducing the danger of armed conflict and seeking cooperative solutions for global problems. Rotblat was active in the group for many years, and he and the group would share the 1995 Nobel Peace Prize.

In awarding the prize, the Nobel committee said it was its hope that the award “will encourage world leaders to intensify their efforts to rid the world of nuclear weapons.”

The committee also noted that Pugwash had been established “in the desire to see all nuclear arms destroyed and ultimately in a vision of other solutions to international disputes than war.”

During his tenure at Pugwash, Rotblat would campaign for the enactment of a treaty in which countries would pledge not to be the first to use a nuclear weapon. He saw this as a first step in the eventual elimination of nuclear weapons, just as similar interim measures had eventually led to conventions outlawing biological and chemical weapons.

Rotblat acknowledged in his Nobel speech that “nuclear weapons cannot be disinvented. The knowledge of how to use them cannot be erased. A nuclear-weapon-free world would be safer than the present one. But the danger of ultimate catastrophe would still be there. The only way to prevent it is to abolish war altogether. War must cease to be an admissible social institution.”