Bruce M. Jakosky
Astrobiology is a discipline that involves trying to understand the origin, evolution, and distribution of life within the universe. It starts with understanding the origin and nature of life on Earth, moves to asking where else in the solar system life might be able to exist and whether life actually is present there, and continues with the potential for life (whether microbial or intelligent) to exist on planets orbiting other stars. Humans have been asking these questions for thousands of years. The different fields of study that make up astrobiology---geology, paleontology, astrophysics, planetary science, biochemistry, evolutionary biology, molecular biology, microbial ecology, and so on---have been around for, in some cases, hundreds of years. Only within the last decade, however, have the modern contributions from these disciplines come together and has our current scientific understanding of the potential for life elsewhere been developed. Recent discoveries have been made on Earth that relate to the existence and nature of life in extreme environments, to new branches of the "tree of life" unknown even one or two decades ago, and to the earliest history of life on Earth. We now recognize that there are places on the planets and satellites in our own solar system that might be able to support an origin of life or its continued existence today, or might have been able to do so in the past. And just within the past decade we have discovered planets orbiting other stars and disks of gas and dust that are thought to be in the process of accumulating into planets. Although the existence of these planets and protoplanetary systems had been suspected, their discovery has changed our perception of the occurrence of planets in fundamental ways.
Issues surrounding the potential for life elsewhere are at the intellectual center of the space exploration program. Recent reports on the directions of space science for the next decade, coming from both the NASA Office of Space Sciences and the National Research Council of the National Academy of Sciences (which provides independent scientific oversight of the NASA programs), have embraced questions about life in the universe as being of immense scientific interest and importance. Even a casual reading of these reports suggests that astrobiology has become the intellectual centerpiece of NASA and the space program, if not the raison d'être for its existence. The vision for space exploration put forward by President George W. Bush on January 14, 2004, emphasizes the search for life as one of the central drivers of the space program, with the idea of human exploration as a major theme.
The search for life elsewhere is one of only a few scientific disciplines that consistently garner the public's deep interest and attention. New discoveries that relate to the potential for life elsewhere are regularly reported on the front page of the New York Times. This interest includes all aspects of astrobiology, including a deeper understanding of life here on Earth, the nature of the planets and satellites in our solar system, and our understanding of worlds outside our solar system. A discovery of evidence that was thought to point to microbial life on Mars made front-page headlines worldwide in 1996, and even drew public comments from then-President Bill Clinton. This strong public interest is an offshoot of the deep significance the possible existence of extraterrestrial life has to many, if not most, people. Whether this meaning relates to addressing the "Big Questions" of our existence, to the possibility of making contact with alien beings, or to the potential impact on our understanding of religion is subject to discussion. Regardless, the connection is real.
There was a time in recent memory when the exploration of space was at the center of the national zeitgeist. In the early 1960s, only forty years ago, there was public excitement, a sense of purpose, and a sense of destiny in the beginnings of the space program. Americans who are over the age of fifty can remember the countdowns of the rocket launches that sent men into space for the first time. People around the world over the age of forty can remember the first manned landing on the Moon and the first steps by humans onto another world. These events truly represented, in Neil Armstrong's words, "a giant leap for mankind." This excitement, however, was rooted in the first exploration of space by humans. The interest in the Moon was in the human drama rather than in the opportunity the landing presented to enhance understanding of another object in our solar system.
That sense of wonder and awe is generally lacking in space exploration today. The human space program no longer generates intense excitement. The search for life elsewhere, however, is able to generate that same level of excitement. Many Americans over the age of thirty remember Carl Sagan's Cosmos series on television, which managed to relate the scientific exploration of space to society here on Earth.
Certainly, the public has always been interested in knowing whether life exists elsewhere in the universe, but that alone is not enough to fuel a research program. It is the dramatic change in our scientific understanding of life that has taken place over the past decade that has brought the questions back to the forefront of space exploration and pushed them to the center of the NASA programs.
Despite their shared interest in life elsewhere, there is very little real interaction between the scientific community and the public. Some individual scientists are trying to understand, explore, and pursue the broader societal and philosophical issues related to their discipline, but scientists as a group show little interest in doing so. And they show even less interest in listening to the public's views about what questions scientists should be trying to address.
Because the tremendous public interest in astrobiology is relatively recent, there has been little opportunity to bring the deep underlying issues that stem from the science before the public. Why is it important to have a dialogue between scientists and the public? The fundamental reason is that scientists are exploring the universe on the behalf of humanity. If the scientists are not addressing the questions that most interest the public, then they are not doing their jobs. Similarly, scientists who are not bringing their results back to the public, in a form that addresses the public interest and in ways that can be understood and appreciated, are not doing their jobs.
But a dialogue between the scientists and the public is not enough. Other groups have important contributions to make to this discussion as well. Astrobiology is an amalgam of existing disciplines, each with different ways of "doing science." There is no single way to define astrobiology. Scientists from one discipline often do not understand the approach taken by scientists from other disciplines, and as a result, they cannot effectively integrate results across disciplines and understand the breadth of their own field. Questions relating to how science is "done" and how we understand the causes behind observed phenomena fall within the category of philosophy of science. As such, they tend to be studied by academics in philosophy departments who may have no formal training in science itself. Most scientists pay little or no attention to philosophy of science, and thus most have little understanding of the validity of their own approaches to doing science. In a field such as astrobiology, which is comprised of such different component disciplines, there is real value in discussing the different philosophical approaches to the science.
Science and religion are often placed at opposite poles in the continuum of human knowledge. Their relationship is often seen as an antagonistic one. Many people think that the discovery of life elsewhere would have a tremendous (and probably deleterious) effect on religion. This view is not new. The religious implications of science discoveries, particularly in astronomy, go back hundreds of years, at least to the time of Galileo's arrest for the heresy of saying that the Earth goes around the Sun. What might the impact on religion be of discovering life elsewhere? What might the ramifications be of searching for life and not finding any? While the scientist clearly has much to contribute to this discussion, any understanding of the religious implications has to include analysis by theologians.
Although many scientists do not appreciate it, exploration science plays a large role in our society. Some planetary scientists may correctly see themselves as explorers but still fail to understand how this exploration fits into the broader scientific enterprise. Why is exploration science important in our society, especially given that there is so little opportunity for practical applications? Why does the federal government support this type of research? Astrobiologists need to understand the relationship between NASA, the federal government, and the public, and to understand as well what drives the support for the science.
There is a common thread running through the last few paragraphs: Astrobiology as science, science as a public activity, and science as public policy address important issues that are central to carrying out the science yet are seldom addressed within the science community. Scientists cannot address these issues alone; a full discussion must involve philosophers, theologians, public policy wonks, and, of course, the public itself.
In a multidimensional dialogue, each group can bring its own background and perspective to the discussion so that the parts can be integrated into a whole. Issues can be addressed at the interface between science and religion, or between science and philosophy, only if each side provides its unique perspective and if the groups are willing to carry on a dialogue. If scientists are to provide their perspective, though, they need to have a perspective!
With this idea in mind, let us examine the philosophical and societal issues in science in general and in astrobiology in particular. This discussion will have two goals: first, to provide a scientist's view of the interactions between astrobiology and the broader societal issues; and, second, to convince practicing astrobiologists that ignoring these issues puts them at risk of becoming disconnected from the broader society.
These broad issues bring together two distinct cultures within the science. The first culture is the traditional scientific view: What discoveries are being made in astrobiology? How can we integrate them into a coherent understanding of the science? What are the implications for our understanding of the potential for life to exist elsewhere, either in our own solar system or beyond, and how can we carry out a research program to determine whether extraterrestrial life actually does exist?
The second culture involves the connections between science and the humanities. What is the broader societal significance of carrying out a scientific program in astrobiology? More generally, what role should science play in society and what is its actual role? In The Two Cultures, published more than forty years ago at the dawn of the space age, C. P. Snow described two distinct cultures that he saw around him at the time---the sciences and the humanities---and lamented that well-educated and high-level practitioners of each were woefully ignorant of the other, and that both groups and society as a whole suffered as a result. The lack of discussion of the social issues in astrobiology today suggests that, to a great extent, this dichotomy still exists.
The relationship between these disciplines was addressed more recently by E. O. Wilson in his book Consilience, which argues that the sciences and the humanities can be connected or united through common concepts and principles. Consilience takes a scientific approach to understanding areas that traditionally fall within the humanities, such as religion, creativity in art, and consciousness, applying scientific techniques to nonscientific areas to show that this can be done productively.
Alternatively, in astrobiology, the different disciplines address different types of questions but can be brought to bear on a common problem---understanding the nature and distribution of life in the universe. This distinction is very important. Rather than insisting on a causal relationship between the sciences and the humanities, we must understand the influence each has on the other. Science should not be done outside the influence of the humanities. After all, scientists are people, they are funded by other people, and people are interested in the results; in other words, science is a truly human endeavor. Similarly, philosophical questions regarding the nature of life, how life and intelligence originated, and whether we are alone in the universe either as life or as intelligent life are based on our understanding of the sciences.
This book is intended as a response to the compelling need for discussion on a number of issues that center on the science of astrobiology yet involve its connections with the broader society:
- There is a remarkable lack of connection between scientists and the public. While most scientists have accepted the now-ubiquitous calls to engage in outreach, outreach as practiced in the space sciences typically involves a one-directional talking at the public rather than a dialogue with the public; it is at best a first step. Scientists as a group do not appreciate the societal issues that underlie their work, and as a result have a difficult time valuing them or responding to them.
- The lofty goals and ideals that characterized the early era of space exploration forty years ago have disappeared and have not yet been replaced by anything of substance. NASA and the United States lack direction with regard to space. This lack of focus emerges in the continued dithering in the wake of the 2003 loss of the space shuttle Columbia over what the role of humans in space should be within the broader space program, and what the role of space science should be.
- There is a lack of discussion within space science of the importance of exploring the universe around us, what the role of exploration should be, and, more generally, what the role of basic research should be.
These topics will be addressed here through a discussion of the role and significance of astrobiology in the larger society. How do philosophy and religion relate to our understanding of the science of life in the universe? Astrobiology is a relatively new science, and there has as yet been very little opportunity to develop these issues. While some will reasonably see the present discussion as "philosophy lite," even a brief and preliminary discussion such as this one can serve to raise the issues. I hope that a more in-depth discussion involving academics from disciplines outside the sciences will follow.
A discussion of the societal issues in astrobiology has to start with an introduction to the scientific issues. What is it about the nature of life on Earth that suggests that there could be life elsewhere? Where in our solar system could life plausibly occur? What processes are responsible for producing the architecture of our solar system? How did these same processes play out in other planetary systems, and thus what is the potential for life beyond our solar system? Equally important, are we deluding ourselves in believing that because life exists on Earth it must exist elsewhere, as if we really need to find something out there? These topics are discussed in chapter 1.
An important related question is, What is life? We have only a single example of life---that found here on Earth. How do we---and can we---extrapolate that concept to life elsewhere? What can we say about what constitutes life? How do we classify entities that are on the border between living and nonliving, such as viruses? Can we put together a "user's guide" to finding or identifying life even without having a unique definition? Chapter 2 contains a discussion of the difficulty of defining life and a rudimentary attempt to deal with these questions.
Chapter 3 addresses the question of whether astrobiology is a science. As a scientific endeavor, exobiology, a close cousin of astrobiology, has been described pejoratively as a discipline without a subject. To determine whether this statement is fair, and to understand how astrobiology operates as a science, we need to understand how science works in general and what science is. This issue touches on questions that are being asked outside the science community that relate to absolute truth, objectivity, and cultural influence in science.
Many of the subdisciplines in astrobiology do not fit neatly into the standard description of experimental science but are better described as historical science. This approach involves observing the manifestations left behind (in the geological record, for example) by past events and trying to construct narratives that describe the sequence of events that must have taken place. Many scientists, even those who practice within this field, do not understand or appreciate this distinction, yet it is fundamental to understanding how to interpret the results of their research. The nature of historical science and the value of historical narratives are explored, with examples drawn from recent astrobiological thought, in chapter 4.
The parallel question to how we do science is why we do science. This topic touches on key questions that include the roles of basic versus applied science, the national science policy, and personal and societal motivations. More specifically, we can address the role of astrobiology in the process of exploring the universe and the role that this exploration plays in our society. Also in this category is the philosophical significance of searching for or finding life elsewhere and what the answers imply for how we choose to construct and promote our space exploration program. These issues are addressed in chapter 5.
Would the discovery of life elsewhere have any impact on religion? A large fraction of the public thinks that it would, although most theologians are less concerned about it. Many issues dealing with the universe outside the Earth touch on religion, including the "anthropic" universe, the potential for life elsewhere, and the potential for intelligent life elsewhere. As part of this discussion it is fair to ask whether science itself can be viewed as a religion. The answer to that question, discussed in chapter 6, has important implications for how society deals with the relationship between religion and science.
Finally, in chapter 7, I revisit the two different cultures within astrobiology---the science and its societal connections. Despite the separation that exists today between basic research and exploration science and the public, it is public interest that supports space exploration. I use the idea of two cultures as a starting point to indicate ways in which the science community needs to redirect itself in order to be responsive to these issues.
To some extent, this book is aimed directly at members of the planetary science, astrophysics, and astrobiology communities; however, nonscientists should understand it as well. My goal is to begin a dialogue about what the role of exploration science is and should be in our society. I take the first step by providing a scientist's perspective and by encouraging the scientific community to address these questions, setting the tone and direction for the real discussions across disciplines that I hope will result.
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