Stephen Jay Gould explains:
Arthur Cain was the summer-up of the whole session. There's a line in Durrell's Alexandria Quartet where the narrator, Pursewarden, says that he's a Protestant in the only meaningful sense of the term — that he likes to protest. Well, moderators are supposed to be moderate, I suppose. Arthur Cain was not. He devoted his entire summary of the conference to a vitriolic attack on this paper, essentially saying that Dick and I knew that adaptation was true because we had to, because it obviously is true. Arthur said that we had attacked it because, although we knew it to be true, we so disliked the political implications of sociobiology, which is based on it, that we abrogated our credentials as scientists.(Emphasis and links mine)
That was so off the wall that it was just amazing. When I got up to give my re-reply, the second coordinator of the conference was standing in front of the podium — which had the motto of the Royal Society, "Nullius in verba," on it — and I asked him to step aside. He was annoyed: why was I asking him to move, that was not fair. But he later realized why I had. Now, I'm stupid about certain things that scientists are supposed to be good at. I'm not particularly quantitative; I'm numerate but not innovative. I'm not a great experimentalist. But I pride myself on having immersed myself in Western culture and having learned some languages, and knowing certain aspects of humanism that many scientists don't take up.
I asked him to step aside, and I said that I thought Arthur had been entirely wrong, that he'd completely misunderstood the motives of my talk, and that I was doing nothing but trying to uphold the motto of the Royal Society, which had sponsored this meeting. The reason that was an effective strategy was that I knew that most people, most members, didn't know what the motto "Nullius in verba" meant. It looks like it means "Words do not matter" or "Do not pay any attention to words," since nullius means "nothing" and verba is "word." So most people think it means that words mean nothing and you have to do the experiment.
But nullius is genitive singular; it can't mean that. It means "of nothing" or "of no one." I knew what the motto meant. I knew that it was a fragment of a statement from Horace — a famous quotation from a poem, in which he says, "I am not bound to swear allegiance to the dogmas of any master." Nullius addictus jurare in verba magister. It's "Nullius in verba," or "In the words of no (master)." It's just a fragment from a larger line.
"That's all I'm doing," I said. "I'm saying that we are not bound to swear allegiance to the dogmas of any master; I'm here to present an alternative viewpoint that's consistent with your own society. How can you castigate me?"