Consilience

I just read E.O. Wilson’s Consilience for the first time. Published in 1998, Consilience represents Wilson’s attempt to bridge the gap between the natural and social sciences.

Given my interests, it is pretty ridiculous that I had not read this book earlier. Although I do research that sits firmly within the realm of natural science, almost everything that I am interested in has pretty direct relevance to human behavior. I want to understand the ways in which humans behave, both through the lens of biological science and by its methods.

If there’s a theme to my research agenda, it is understanding the stability of systems of interactions. Whether these interactions occur between non-human animals or within our own species, I want to know what causes some systems to collapse and others to survive. I am particularly interested in cooperation, an evolutionary strategy employed most effectively by human beings. If there’s a disconnect between the natural and social sciences, it is a fault line that cuts straight through my interests, potentially threatening the viability of my research agenda.

Many of my courses flirt with the boundary between the natural and social sciences. In my ecology class we discuss the impact of modern human culture on the earth’s ecosystems, and to do so in a social vacuum is to exempt humans from the analysis applied to the rest of the living world. Although my human evolution course covers early anatomical developments in our ancestors, it is impossible to avoid discussing the prominence of culture in our evolutionary success. Most of my behavioral ecology class focuses on non-human animals, but students always wish to discuss whether the insights of animal behavior apply to humans. Closest to my research interests, my course exploring the evolution of cooperation tackles head-on the question of what constitutes “human nature” and how biological and cultural evolution interact to produce cooperation. If I wish to accomplish my objectives as a teacher, I must find a way to tread comfortably along the borderlands that lie between biology and the social sciences of psychology, anthropology, political science, economics, and sociology.

So what does Wilson have to say about work at the boundary between the natural and social sciences? First and foremost, he argues for consilience, the unity of all knowledge. In Wilson’s view, the greatest threat to this unity has been the separation of the natural sciences from the social sciences, a process that has created distinct realms of dominion occupied by each set of disciplines. Assigned to the natural sciences are questions about the elemental nature of our universe (physics and chemistry) as well as all larger abiotic phenomena (geology, meteorology, astronomy) and almost all of the biotic phenomena on the earth (biology), including the physiological functions of human beings (medicine). Assigned to the social sciences are all phenomena that relate to the behavior of human beings, from individual behavior (psychology) to small-scale social interactions (anthropology) and all the way up to the functions of complex societies (sociology, economics, political science).

Roughly, one can see the distinction between the social and natural sciences as a line along a continuum of scale that cuts across a dimension of the universe that happens to contain humans. Moving down in scale from a single human being we can see that this person is composed of a nested hierarchy of organs, tissues, cells, organelles, molecules, atoms, and subatomic particles. Over this large swath of scales the natural sciences unequivocally maintain dominion in modern western society. Although other cultures may still maintain alternative depictions of what we are “made of”, the value of the understanding produced by the natural sciences in these realms is rarely questioned within our society. Once we extend past a single human being into the social realm, we enter the domain traditionally occupied by the social sciences. In order to explain the behavior of this person in relation to others we need psychology. In order to explain the family this person belongs to, or her affiliation with a mid-sized social group, we need anthropology. In order to understand the larger society to which she belongs, we need sociology, political science, and economics. What Wilson argues is that these fields have traditionally failed to incorporate insights and methods from the natural sciences.

The disciplines within the natural science are consilient, taking into account the insights provided at more elemental scales. A chemist uses insights from physics to understand the interaction of molecules. Cell biologists rely on insights from biochemistry in order to understand the workings of the cell. Animal behaviorists depend on the insights of cell biology to understand the neurological basis of the behaviors they observe. In fact, consilience is expected in the natural sciences: any theory explaining phenomena at one scale must do so in a manner that is consistent with understanding established at smaller scales of understanding. In addition, the methods of the natural sciences are consilient; while specific tests and experiments may vary, the general “scientific method” is consistent across all disciplines, such that a biologist may not understand the specifics of an experiment performed to test hypotheses in the field of particle physics but should be able to understand the general method of inquiry being used.

In contrast, the social sciences are not consilient. First and foremost this lack of unity emerges from an abrupt break in the way that knowledge is propagated up the levels of understanding. As we take our walk along disciplines attempting to understand scales ranging from subatomic particles to the entire human population, we hit an abrupt bump in the road. Wilson argues that this bump is the interface between the natural sciences and the social sciences, a place where insights from smaller scales of understanding cease to inform the larger scales, and a whole new set of disciplines emerges de novo and in isolation. Biology, the natural science tasked with explaining the largest scales of organization amongst living creatures, is deemed wholly inappropriate or unnecessary for understanding human beings and their organization above the scale of the individual and her physiology.

Wilson makes a strong argument that this lack of consilience has prevented us from understanding the way our world works at scales above an individual human being. I am inclined to agree with this assessment, particularly given that human social organization — while clearly unique in its scale and complexity — represents only one of many interactive systems at scales above the individual organism. To ecology and evolution we relinquish the difficult tasks of understanding how thousands of species interact to form a fairly stable ecosystem and why the species within that system change through time, but when it comes to humans we deem the task too different to allow for similar analysis.

Wilson tackles head-on the argument that upholds the contention that humans are somehow fundamentally different. The argument is, of course, that human culture sets us apart from all other organisms. On its face this argument makes sense: although there has been a good amount of research showing culture in animals ranging from whales to corvids to our closest primate relatives, the scale of human culture simply dwarfs all other animal cultures. But does this mean that our culture exempts us from the usual rules, illuminated by the biological sciences, that govern the lives of other organisms? In order to justify a break in the continuum of understanding between the natural and social sciences, one has to support the rather extreme stance that human culture is not at all constrained by biology.

Wilson argues that this is the stance defended by most of the social sciences. We are a “blank slate” on which culture writes its arbitrary instructions, and our behaviors are predominantly governed by what we are taught by the culture within which we live. Such a view suggests that the process of biological evolution has been superseded and therefore interrupted, being replaced by a system of cultural change. Wilson counters this argument with the concept of gene-culture coevolution, a scientifically-nascent but generally-accepted depiction of how humans have evolved in recent time. According to this model, humans evolved to incorporate culture because elements of culture increase the chances of surviving and reproducing. Immediately this set in motion a dialogue between the two evolutionary processes. Human biology and its evolution through genetic changes remained the “platform” or “vehicle” for cultural evolution. But because cultural ideas and artifacts had the power to be propagated by people, cultural evolution also began to occur in parallel with biological evolution. Cultural evolution became so critical to the success of the human species that culture became in its own right a very strong force of selection on biological traits. We evolved to be intensely-cultural organisms.

The question then becomes “Have we become so reliant on culture that biology no longer matters?”. How you answer this question determines whether or not you see the current lack of consilience between disciplines as tragic or appropriate. If culture truly has trumped biology and humans now represent a highly-malleable and unchanging biological vehicle for culture, then it is entirely appropriate to ignore the insights of the natural sciences in considering how and why humans behave in particular ways. But if you still see biology as a partner of culture, we have to consider the competing needs of genes and memes as both evolve. Wilson clearly believes that although the brain is a very flexible organ designed in large part to assimilate the culture to which it is exposed, it is far from a “blank slate”. Giving an overview of the major accomplishments of neuroscience, he argues that understanding how the brain works will become an indispensable tool for those who want to understand how culture works. Wilson employs what I think is a valuable metaphor, describing culture as tethered by a “genetic leash”; culture can wander into a variety of places, but human biology limits us from reaching many if not most cultural possibilities.

Although it is easy to become entirely focused on the different explanations of human behavior entertained by the natural and social sciences, there are also differences in methodology that need to be considered. Although part of his argument, Wilson places less emphasis on this issue. Beyond the question of whether knowledge gained in the natural sciences should contribute to the ruminations of the social sciences, we also need to consider whether the methods of the natural sciences should be part of achieving consilience with the social sciences. Given the influence of postmodernism on many of the social sciences, it is easy to see a pretty grand methodological chasm between the disciplines. On one side are the natural sciences with empirical methods designed to objectively uncover material reality, and on the other are the social sciences forever engaged in trial-and-error arguments about the nature of truth (which is in the end deemed unknowable).

Although I do see a methodological difference between the natural and social sciences, I think this difference occurs on multiple dimensions and is continuous rather than discrete. Sure, there are still academic areas where truth is deconstructed into nothing, but no one advocates for the employment a postmodernist engineer to design our airplanes or medical devices. And to characterize the social sciences as never consilient with the natural sciences (which Wilson never quite does, but flirts with) is to paint a rather simplistic cartoon version of a large and diverse set of disciplines. Methodologically there is a lot of very empirical work done in the social sciences. In fact, the fields of ecology and evolution have frequently benefited from empirical methods pioneered in the social sciences (meta-analysis and the comparative method are two such techniques). Where we don’t see the methods of the natural sciences used it is often because to do so would be unethical (unlike mice, humans tend to speak up for themselves when subjected to controlled experimentation) or untenable (due to the large scale on which some phenomena unfold, a constraint faced by sociologists and ecologists alike).

If there’s an issue that I wish that Wilson had spent more time considering, it is scale. Although he recognizes that the transition from discipline to discipline is in part mediated by scale, some of the difficulties of scale are glossed over in Consilience. On a number of occasions Wilson discusses the great value of reductionism and how well it has served the natural sciences. What he fails to mention is that reductionism has run into a series of problems deep within the heart of the natural sciences. We can understand the nature of material objects in part because we can reduce them to their constituent molecules and atoms. But the opposite direction, predicting what objects will form based on what we know about molecules and atoms, is more difficult.

Wilson does briefly mention emergence and even uses a metaphor (Ariadne’s Thread) to discuss how much easier it is to scale down in one’s understanding than to scale up, but he never tackles the possibility implicit in this reality: that at some level of complexity, the whole may not be predictable from its parts. While we wish to make the natural sciences and social sciences consilient (which implicitly means importing the smaller-scale knowledge of biology into the larger-scale understanding of psychology/anthropology/sociology/economics) we also have to recognize that at some higher scale properties may emerge that render lower levels of understanding useless. You can’t understand an elephant based on knowledge of its atomic structure. Emergence is a real phenomena, and suggests that the real consilience mostly needs to occur at the boundary between the natural and social sciences. Our consideration of human behavior could benefit from an integration of the natural and social sciences, but at some critical scale you can’t understand a society based on the behavior of individuals alone.

I am a very firm believer in the power of scientific knowledge. Much of what we have accomplished as a species has arisen out of the particular culture we call the natural sciences. It is foolish to ignore the insights into human behavior that can be gleaned from biology. There is such a thing as truth, and sometimes we can even pare this truth into some degree of predictability. But understanding how the universe works is not the same as understanding how it ought to be. Values expressing how the world ought to be cannot be tested by the methods of the natural sciences, so perhaps we ought to be limiting our expectations of how consilient we can make the natural and social sciences. While it is impossible to argue what ought to be from what is, Wilson rightly suggests that it is foolish to ignore what is in the pursuit of a particular vision of how things ought to be.

Reading Consilience is an adventure covering a lot of ground. Wilson gives an overview of the current divide between the natural and social sciences, arguing that consilience is the key to progress. In the end he suggests that consilience is critical to our own survival: if we don’t find a way to integrate our understandings, we risk destroying the planet upon which we survive (which would be the ultimate proof that culture is not independent of biology!). Although the book is over a decade old, the challenge it issues still seems timely.