Figuring out whether someone committed plagiarism is usually straightforward. You compare the two texts to see how much of one appears verbatim in the other. Even if some words have been changed, there is often a pattern of similarities that can’t be coincidental. It’s not that hard.

Determining whether someone swiped an idea, or a set of ideas, is another beast entirely. In a review in the June 7 issue of The New York Review of Books, the possibility is raised that Terence W. Deacon, chairman of the anthropology department at the University of California at Berkeley, borrowed heavily and failed to credit core ideas in his book, Incomplete Nature: How Mind Emerged From Matter, from at least two scholars. Here’s what the NYRB reviewer, Colin McGinn, a professor of philosophy at the University of Miami, writes:

One would never think from reading Incomplete Nature that the author’s main contentions have already been systematically developed by others, and that there is in fact hardly an original idea in the book. Two works, in particular, stand out in the prior literature: Dynamics in Action by Alicia Juarrero and Mind in Life by Evan Thompson. Neither book is cited by Deacon, although they cover much the same ground as his—far more lucidly and insightfully.

McGinn goes on:

I have no way of knowing whether Deacon was aware of these books when he was writing his: if he was, he should have cited them; if he was not, a simple literature search would have easily turned them up.

There’s more to this story. In fact, a mini-controversy has been burbling for months. In a review published in Nature last December, Evan Thompson (mentioned above in McGinn’s review) wrote that Deacon “doesn’t discuss other theorists who have given similar accounts of life and mind,” mentioning his own book and Juarrero’s.

In an interview, Thompson, a professor of philosophy at the University of Toronto, said he believed that there was a “substantial overlap of ideas” and that Deacon was guilty of “significant scholarly oversight.” He stopped short of accusing Deacon of actually having cribbed.

An e-mail campaign of sorts has been carried out by Michael Lissack, executive director of the Institute for the Study of Coherence and Emergence, and a self-styled whistle-blower, to persuade Deacon and officials at Berkeley to take some kind of action. Lissack says he gave a copy of Juarrero’s book to Deacon a few years ago at a conference (Deacon says that’s not true).

Juarrero, a professor of philosophy at Prince George’s Community College, in Maryland, has compiled a detailed spreadsheet of apparent similarities between the structure of the arguments in the two books and the examples used to make those arguments.

And there do seem to be plenty of similarities. Deacon acknowledged those in an interview, but he said that they were superficial and that his argument and Juarrero’s were substantially different. Part of the reason she and others are upset, Deacon said, is that he is not a philosopher—his background is in biological anthropology. He is an outsider to the field, he argued, and so philosophers are circling their wagons. “I don’t give all the philosophers their due because I didn’t intend to write a book about philosophy,” he said.

Untangling all of this is tricky. Whether one person handed another person a book at a conference years ago is tough to prove, and wouldn’t necessarily matter even if it happened (how many unread books are on your shelf?). Plus the topics in the books are, for nonphilosophers, a bit esoteric: the nature of causation, the evolution of human consciousness, dynamic systems theory. Deacon’s book is about how mind emerged from matter. Juarrero wants to discover the difference between “a wink and a blink.”

I called McGinn, who wrote the review. He doesn’t know any of the people involved, though he did receive an e-mail from Juarerro stating her case. So he read her book, Thompson’s book, and Deacon’s book. “I was a little outraged when I realized the degree of overlap,” he said. That overlap, according to McGinn, “is not superficial at all.” Discovering that other researchers had already proposed more or less the same ideas would have required, he contended, just a few minutes on Google.

Deacon conceded that his citations “don’t go deep enough” and said he takes “responsibility for that.” He insisted, though, that he hadn’t read either book when he wrote his, and that any failure to give credit was unintentional. “Should I apologize to everyone I didn’t cite?” he asked. “I don’t think so.”