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A Quest For The Unattainable Unification Of Knowledge


In his recent book, The Meaning of Human Existence, the celebrated evolutionary biologist, entomologist and essayist Edward Wilson sets off to chart a possible path toward the unification of the sciences and the humanities — taking off from his 1998 book Consilience: The Unity of Knowledge. If we are successful, claims Wilson, we should arrive at a deeply transformative understanding of the meaning of our existence.

The stakes are high, and the fact that The Meaning of Human Existence was shortlisted for the National Book Award means that people are paying attention. (And that Wilson's prose is truly inspired and engaging, which is definitely the case.)

The starting point, as Wilson argued in Consilience, is what Harvard historian of science Gerald Holton called "The Ionian Enchantment." This notion — that behind nature's manifest diversity there is a simple, unified explanation — can be traced back to the pre-Socratic Thales of Miletus. Being mainly interested in the material aspect of reality, Thales suggested that all matter is but water. The meaning of this claim is more metaphysical than physical, of course. The essential point is that deep below the chaos we perceive out there, there is an underlying unified structure. Everything springs from that structure. Get to it and you will crack the mystery of existence, from simple to complex, from electrons to love.

According to Wilson, the Ionian Enchantment equates science with a religious quest. "Such, I believe, is the source of the Ionian Enchantment: Preferring a search for objective reality over revelation is another way of satisfying religious hunger," he states.

Wilson's approach is based on the assumption that reductionism rules knowledge. According to this view, the unity of the sciences starts and ends with physics, given that physics sets the rules from bottom up. The argument goes somewhat like this: Since we are made of elementary particles of matter, understanding the laws that dictate the behavior of these particles is a precondition to understanding everything else. The plan is to first unify physics, extrapolate to the other physical sciences, and then on to biology and the neurosciences. Once we are there, we will have a clear understanding of the fundamental character of human emotions — and we are pretty much done. And given that the humanities are a product of the human brain, they too will be encompassed by this sweeping approach to the unity of knowledge.

In order to achieve this goal, apart from the unification of physics, scientists must convince the humanists to come onboard, welcoming this new way of thinking about their disciplines. Good luck with that.

Wilson doesn't shun the humanities. Quite the opposite, he celebrates them: "They are the natural history of culture, and our most private and precious heritage."

What he means here is that the humanities, as the name says, are very much a product of who we are, starting from our evolutionary history: To understand history we must start in prehistory, Wilson claims, quite correctly. We can't separate our ability to create art from the long evolutionary processes that slowly molded Homo Sapiens from a two-million-year-old lineage of primate bipeds. There is, thus, a line connecting the Big Bang to the origin of matter to the origin of life to the origin of complex life to the origin of humans to our creative output as a species. This is the consilience Wilson is after, the bridging of the cosmic and human history.

Can this be done? I sympathize deeply with Wilson's quest:

Sadly, the quest is unattainable in principle and in practice. In principle, because the notion of unification in physics, the starting point of Wilson's argument, doesn't make sense epistemologically. In practice, because we can't have enough knowledge to build a unified view of reality.

As the historian of ideas Isaiah Berlin noted, against the Ionian Enchantment there is the Ionian Fallacy, the assumption that such unified and absolute rendering of knowledge is a realistic goal. Any system of knowledge that claims to have reached completeness is clearly blind to how knowledge is acquired — a point I elaborate in The Island of Knowledge. As the 17th-century French philosopher Bernard de Fontenelle noted, all philosophy is the product of two things only: curiosity and shortsightedness. The acquisition of knowledge is by its very nature a branching phenomenon: As we know more, we realize there is more to know.

There is, of course, a trend to find simplified and embracing descriptions of natural phenomena — and this is a leading force behind physics. But it is naïve to expect that we can reach the end of the road, so to speak. At best, we can achieve a provisional unified description of the physical knowledge at hand, limited to how elementary particles interact with one another; with that we must acknowledge that a new tool or hypothesis may break this structure down, asking for a broader stance.

For an illustration, just think of how gravity has been described in the past 500 years: first in the Aristotelian fashion of natural movement, then the Newtonian action-at-a-distance, then the Einsteinian as a curvature of space-time. And we are currently rethinking the nature of gravity, which may not even be a force like the other ones.

There is no reason to expect that we humans can get to the ultimate nature of reality; we must learn to live with the mystery, with the fact that we cannot know all there is to know.

Another limiting problem with the unification of the physical sciences is the issue of complexity. Even if we are all made of atoms, we can't use atomic physics to describe our physiology and much less our behavior. Different laws are called for as matter coalesces into more complex structures, and these laws are not reducible to the previous ones in a nice continuous way. They are new laws, having their own ontological power. To go into Wilson's territory, the collective group behavior of ants is very far removed from the metabolic rules at the individual ant's cellular level, and even more dramatically from the properties of the atomic nuclei in every atom comprising the ant. If this weren't the case, biologists would all have to be experts in quantum mechanics.

So much for limitations of principles. In practice, too, however, the unification of knowledge is unattainable. We are bound by our technological limitations to only probe a fraction of what's out there. Seeing more doesn't mean seeing all.

Wilson is clearly an optimist when it comes to science solving some of its current dilemmas. I was struck by his confidence that we will soon have intelligent machines:

How does Wilson know that? There are enormous differences between a computer than can beat a chess master and a machine that is intelligent in the sense of being able to create it own sets of rules and grow more intelligent as it does so. There are cellular automata algorithms that allow for machines to learn, for sure. They do so by collecting and analyzing data and coming to certain conclusions based on the process. But cellular automata are not the same as human intelligences; they don't have the ability to feel and process emotion; they don't have a subjective sense of the self as we do. Complex emotions don't depend on techniques of machine learning or processing speed. As many philosophers of mind contend, there is a big difference between unveiling the mechanisms by which the brain processes information and the ways by which the mind emerges from the brain. (See Alva's essay here last Friday, or essays by some of the so-called New Mysterians, including Colin McGinn, David Chalmers, Thomas Nagel, and Steve Pinker.) We don't even know if it's possible for a machine to emulate the human mind without a sense of the human body.

Can there be some kind of unification of knowledge? One way to think about the issue is to identify what are the common trends in the history of humanity, the essential urges that define us all: to learn, to love and be loved, to create bonds with members of the many tribes we belong to, to defend those bonds. The hope to know it all, to construct a grand edifice of knowledge seems to me to be an impoverishing one. We don't want to arrive at an end where all is one; we want to celebrate the plurality of learning, the unstable nature of knowledge so that we keep on searching and growing.

There are many ways to look at the world — and science provides one of them. I love it, of course, and have dedicated my professional life to it. As the philosopher Jerry Fodor once wrote, "The success of the sciences is one thing: the unity of science is quite another." There is no question that science can illuminate the origins of human creativity; there is no question that the humanities can both augment and illuminate the ways in which we create. But the true strength of our very human ability to ponder beyond the immediately necessary is that we will never know all the questions to ask. It's the incompleteness of knowledge that makes us matter.

Marcelo Gleiser, a world-renowned theoretical physicist and cosmologist, is professor of natural philosophy, physics and astronomy at Dartmouth College. He has published over 100 peer-reviewed papers and is the author of dozens of essays and four books, including The Island of Knowledge: The Limits of Science and the Search for Meaning. You can keep up with Marcelo on Facebook and Twitter: @mgleiser

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Marcelo Gleiser is a contributor to the NPR blog 13.7: Cosmos & Culture. He is the Appleton Professor of Natural Philosophy and a professor of physics and astronomy at Dartmouth College.