Thomas Nagel is a leading figure in philosophy, now enjoying the title of university professor at New York University, a testament to the scope and influence of his work. His 1974 essay "What Is It Like to Be a Bat?" has been read by legions of undergraduates, with its argument that the inner experience of a brain is truly knowable only to that brain. Since then he has published 11 books, on philosophy of mind, ethics, and epistemology.
But Nagel's academic golden years are less peaceful than he might have wished. His latest book, Mind and Cosmos (Oxford University Press, 2012), has been greeted by a storm of rebuttals, ripostes, and pure snark. "The shoddy reasoning of a once-great thinker," Steven Pinker tweeted. The Weekly Standard quoted the philosopher Daniel Dennett calling Nagel a member of a "retrograde gang" whose work "isn't worth anything—it's cute and it's clever and it's not worth a damn."
The critics have focused much of their ire on what Nagel calls "natural teleology," the hypothesis that the universe has an internal logic that inevitably drives matter from nonliving to living, from simple to complex, from chemistry to consciousness, from instinctual to intellectual.
This internal logic isn't God, Nagel is careful to say. It is not to be found in religion. Still, the critics haven't been mollified. According to orthodox Darwinism, nature has no goals, no direction, no inevitable outcomes. Jerry Coyne, an evolutionary biologist at the University of Chicago, is among those who took umbrage. When I asked him to comment for this article, he wrote, "Nagel is a teleologist, and although not an explicit creationist, his views are pretty much anti-science and not worth highlighting. However, that's The Chronicle's decision: If they want an article on astrology (which is the equivalent of what Nagel is saying), well, fine and good."
The odd thing is, however, that for all of this academic high dudgeon, there actually are scientists—respected ones, Nobel Prize-winning ones—who are saying exactly what Nagel said, and have been saying it for decades. Strangely enough, Nagel doesn't mention them. Neither have his critics. This whole imbroglio about the philosophy of science has left out the science.
Nagel didn't help his cause by (a) being a philosopher opining on science; (b) being alarmingly nice to intelligent-design theorists; and (c) writing in a convoluted style that made him sound unconvinced of his own ideas.
The Florida State University philosopher of science Michael Ruse, who has written extensively about arguments over Darwinian theory, says Nagel is a horse who broke into the zebra pen. Evolutionary biologists don't like it when philosophers try to tell them their business: "When you've got a leader of a professional field who comes in and says, as a philosopher, 'I want to tell you all that Darwinian evolutionary theory is full of it,' then of course it's a rather different kettle of fish."
Joan Roughgarden, an ecologist and evolutionary biologist at the Hawaii Institute of Marine Biology, agrees that evolutionary biologists can be nasty when crossed. "I mean, these guys are impervious to contrary evidence and alternative formulations," she says. "What we see in evolution is stasis—conceptual stasis, in my view—where people are ardently defending their formulations from the early 70s."
Nagel really got their noses out of joint by sympathizing with theorists of intelligent design. "They do not deserve the scorn with which they are commonly met," he wrote. "It is manifestly unfair." To be sure, he was not agreeing with them. He notes several times that he is an atheist and has no truck with supernatural gods. He views the ID crowd the way a broad-minded capitalist would sum up Marx: right in his critique, wrong in his solutions. But ID, he says, does contain criticisms of evolutionary theory that should be taken seriously.
Whatever the validity of this stance, its timing was certainly bad. The war between New Atheists and believers has become savage, with Richard Dawkins writing sentences like, "I have described atonement, the central doctrine of Christianity, as vicious, sadomasochistic, and repellent. We should also dismiss it as barking mad. ..." In that climate, saying anything nice at all about religion is a tactical error.
And Nagel is diffident about his ideas. Take this sentence, which packs four negatives into 25 words: "I am not confident that this Aristotelian idea of teleology without intention makes sense, but I do not at the moment see why it doesn't." Mind and Cosmos is full of such negatively phrased assertions. If you're going to make a controversial claim, it helps to do so positively. It also helps to enlist distinguished allies. Nagel has done nothing of the sort. Which is strange, because he has plenty of allies to choose from.
Natural teleology is unorthodox, but it has a long and honorable history. For example, in 1953 the evolutionary biologist Julian Huxley argued that it's in the nature of nature to get more advanced over time. "If we take a snapshot view, improvement eludes us," he wrote. "But as soon as we introduce time, we see trends of improvement."
More recently, Kevin Kelly, founding editor of Wired, made the case for teleology as clearly as could be in his book What Technology Wants: "Evolution ... has an inherent direction, shaped by the nature of matter and energy." That is, there may be laws of nature that push the universe toward the creation of life and mind. Not a supernatural god, but laws as basic and fundamental as those of thermodynamics. Robert Wright said much the same in Nonzero: The Logic of Human Destiny: "This book is a full-throated argument for destiny in the sense of direction." Those books prompted discussion among the literati but little backlash from evolutionary biologists. Ruse thinks that's because the authors are science writers, not scientists: "At a certain level, it's their job either to give the science or to put forward provocative hypotheses, and nobody takes it personally."
But highly regarded scientists have made similar arguments. "Life is almost bound to arise, in a molecular form not very different from its form on Earth," wrote Christian de Duve, a Nobel laureate in physiology or medicine, in 1995. Robert Hazen, a mineralogist and biogeologist at the Carnegie Institution for Science, struck a similar note in 2007: "With autotrophy, biochemistry is wired into the universe. The self-made cell emerges from geochemistry as inevitably as basalt or granite." Harold J. Morowitz, a biophysicist at George Mason University, argued that evolution has an arrow built into it: "We start with observations, and if the evolving cosmos has an observed direction, rejecting that view is clearly nonempirical. There need not necessarily be a knowable end point, but there may be an arrow."
Nagel discusses none of that work. He asserts only that evolution is directional, without making a case for it. That has left him open to a number of obvious rebuttals. The biologist H. Allen Orr, at the University of Rochester, pointed out that some species become less complex—parasites, for example, after learning how to steal resources from their hosts. And many species, such as sharks, have been happy to stay just the way they are for millions of years. Only one species—us—has bothered to reach sentience. "The point is," Orr wrote in The New York Review of Books, "that if nature has goals, it certainly seems to have many and consciousness would appear to be fairly far down on the list."
Indeed, biologists usually argue that when you do get progress, it came about by accident.
When you have millions of species taking random walks through the wilds of genetic variation and natural selection, some will, by the luck of the draw, become more complex and more capable. That is, when there is an overall increase in variance, some of the variants will be more complex and capable than their ancestors. Biologists say that such ascents in complexity happen "passively."
Yet some scientists think that increases in complexity also happen "actively," that is, driven by physical laws that directly favor increases in complexity. As a group, these scientists have no sympathy for intelligent design. However, they do see reasons to think that seen as a whole, life does go from simple to complex, from instinctual to intellectual. And they are asking if there are fundamental laws of nature that make it happen.
Perhaps the best known of these scientists is Stuart Kauffman, of the Santa Fe Institute, who argues that the universe gives us "order for free." Kauffman has spent decades on origin-of-life research, aiming to show that the transition from chemistry to metabolism is as inevitable as a ball rolling down a slope. Molecules on the early earth, he suggests, inevitably began to catalyze themselves in self-sustaining reactions ("autocatalytic networks"), converting energy and raw materials into increasingly complex structures that eventually crossed the boundary between nonliving and living. Nagel mentions his work once, briefly, in a footnote.
Kauffman has plenty of company. The paleontologist Simon Conway Morris, at the University of Cambridge, has argued that natural structures such as eyes, neurons, brains, and hands are so beneficial that they will get invented over and over again. They are, in effect, attractors in an abstract biological space that pull life in their direction. Contingency and catastrophe will delay them but cannot stop them. Conway Morris sees this as evidence that not only life but human life, and humanlike minds, will emerge naturally from the cosmos: "If we humans had not evolved, then something more or less identical would have emerged sooner or later."
Other biologists are proposing laws that would explain evolutionary ascent in fundamental terms. Daniel McShea and Robert Brandon, a biologist and a philosopher of science, respectively, at Duke University, have argued for what they call a "zero-force evolutionary law," which posits that diversity and complexity will necessarily increase even without environmental change. The chemist Addy Pross, at Ben-Gurion University of the Negev, in Israel, argues that life exhibits "dynamic kinetic stability," in which self-replicating systems become more stable through becoming more complex—and are therefore inherently driven to do so.
Still other scientists have asked how we could measure increases in complexity without being biased by our human-centric perspective. Robert Hazen, working with the Nobel Prize winner Jack Szostak, has proposed a metric he calls "functional information," which measures the number of functions and relationships an organism has relative to its environment. The Harvard astrophysicist Eric Chaisson has proposed measuring a quantity that he calls "energy-rate density": how much energy flows through one gram of a system per second. He argues that when he plots energy-rate density against the emergence of new species, the clear result is an overall increase in complexity over time.
While the jury is most definitely out on whether these proposed laws and measures are right or wrong (and if right, whether they are profound or trivial), this is a body of work that Nagel could have drawn upon in making his argument. He apparently felt it was acceptable to ignore the science. "Philosophy cannot generate such explanations," he wrote; "it can only point out the gaping lack of them." But there is no gaping lack of attempts to supply them. "He's done so little serious homework," says Michael Ruse. "He just dismisses origin-of-life studies without any indication that he's done any work on it whatsoever."
In short, Mind and Cosmos is not only negative but underpowered, as if Nagel had brought a knife to a shootout. (He declines to comment, telling me by e-mail, "I have a longstanding aversion to interviews.")
But Nagel's goal was valid: to point out that fundamental questions of origins, evolution, and intelligence remain unanswered, and to question whether current ways of thinking are up to the task. A really good book on this subject would need to be both scientific and philosophical: scientific to show what is known, philosophical to show how to go beyond what is known. (A better term might be "metascientific," that is, talking about the science and about how to make new sciences.)
The pieces of this book are scattered about the landscape, in a thousand scraps of ideas from biologists, physicists, physicians, chemists, mathematicians, journalists, public intellectuals, and philosophers. But no book has yet emerged that is mighty enough to shove aside the current order, persuading scientists and nonscientists alike, sparking new experiments, changing syllabi, rejiggering budget priorities, spawning new departments, and changing human language and ways of thought forever. On the Origin of Species did it in 1859. We await the next Darwin.