Two recent science stories, one in anthropology and the other in physics, have me wondering which field is "hard" and which "soft."

The first story involves the decision of the American Anthropological Association to delete the word "science" from its mission statement. That step provoked squawks from anthropologists who've struggled to counter the image of their field as a branch of the humanities. Whereas sciences are "empirical," the humanities are "analytic, critical or speculative," as Nicholas Wade put it in The New York Times.

Science-oriented anthropologists want their field to be lumped together not with historians and literary critics—God forbid!—but with physics, supposedly the gold standard of hard science. The irony is that parts of physics are less empirical and more speculative than the most humanistic anthropology. I'm not talking about what the physicist Sean Carroll calls the physics of "everyday life"; as Carroll pointed out last fall on his blog Cosmic Variance, physicists' understanding of the reality we can access in experiments is rock-solid.

But in part because of this success, some ambitious physicists have increasingly ventured beyond the boundaries of measurable reality into the unmapped realms where dragons roam. That brings me to the physics story in the news. Roger Penrose and V. G. Gurzadyan recently proposed that minute ripples in the cosmic microwave background—the afterglow of the big bang—originated from the collision of monster black holes in another universe that preceded our cosmos, and may have spawned it; moreover, our universe might be just one of an infinite series spawned by such cataclysms.

My reaction to reading about this idea was: Far out! Penrose, one of the most famous, creative physicists in the world, along with Gurzadyan had dusted off the old oscillating universe theory of the cosmos, which I always liked. But not for a nanosecond did I think their proposal was true. Other theorists quickly pointed out problems with the hypothesis, but if they had supported it, I still wouldn't have believed it, because the proposal is literally too far out; it can never be confirmed in the way that the existence of, say, quarks has been confirmed, or the big bang itself.

I call this highly speculative theorizing "ironic science," because it makes assertions that are more akin to literary criticism or even literature than conventional science. Another useful term is "faction," coined by the anthropologist Clifford Geertz—the archetypal "literary" social scientist—to describe his field. Geertz, whom I profiled for Scientific American in 1989, defined faction as "imaginative writing about real people in real places at real times," but the term could apply to imaginative riffing on all sorts of phenomena.

Geertz, who died in 2006, would have been amused by the recent ruckus over anthropology's scientific status. He did not consider anthropology to be "merely" a humanistic or even literary enterprise, devoid of any empirical content. Anthropology is "empirical, responsive to evidence, it theorizes," Geertz told me, and practitioners can sometimes achieve a "non-absolute" falsification of ideas. Hence it is a science, one that can achieve progress of a kind. On the other hand, "nothing in anthropology has anything like the status of the harder parts of the hard sciences, and I don’t think it ever will."

Geertz, who worked at the Institute for Advanced Study in Princeton, N.J., where he often crossed tracks with the string theorist Edward Witten, added that the doubts afflicting anthropology seemed to be springing up in many other fields, including physics. "The kind of simple self-confidence in science that there once was doesn’t seem to me to be so pervasive," Geertz said. "Which doesn't mean everybody is giving up hope and wringing their hands in anguish and so on. But it is extraordinarily difficult."

In retrospect Geertz might not have given anthropology enough credit, especially in comparison with physics. Anthropologists gather data—by observing rainforest hunters in Amazonia, excavating a Neolithic settlement in Jordan, carbon-dating an Ardipithecus jaw bone dug up in Ethiopia—and then try to figure out what it all means. This act necessarily involves lots of interpretation and imagination, and hence subjectivity, and it culminates in highly speculative theories—such as the demonic-males theory, which I recently criticized. But even at its most hermeneutical, anthropology still addresses real things: actual primates in actual places.

Many physicists, on the other hand, theorize about phenomena that are not only extremely remote in space and time but might not even exist. Physicists conjecture what's happening at the Planck scale, a microrealm even more distant, in a way, than the farthest reaches of the universe. They speculate about the era before the big bang, and about other universes that might be mutant versions of our own. They postulate strings, membranes, higher dimensions and other stuff whose existence, like that of God, cannot be proved or disproved. Do these imaginings even deserve to be called faction?

Addendum: My last post, on "truthiness," provoked comments from Tabitha Powledge, Randy Olson, Matt Nisbet and my so-called friend David Berreby, who likens me to both Charlton Heston and Martha Stewart. Make up your mind, David!

Image: Black hole illustration, courtesy of Wiki Commons