Gaia: From Fanciful Notion to Research Program

GAIA: FROM FANCIFUL NOTION TO RESEARCH PROGRAM DAVID B. RESNIK* Introduction The idea that the Earth is itself alive can be traced to the ancient Greeks, who developed the concept of Mother Earth or Gaia. Since modern science has relinquished many of its teleological and animistic concepts, the Earth is now regarded as an inaminate substratum which supports life but which is not, itself, alive. Even so, for the last three centuries scientists have recognized that life can shape the physical environment . In the early 1970s, Brirish scientist James E. Lovelock and American microbiologist Lynn Margulis reintroduced Gaia as a novel way of looking at the Earth's biosphere. Lovelock and Margulis argued the Earth's biota, soil, atmosphere, and oceans constitute a self-regulating , "living" system, which they named "Gaia" [1—4]. Since that time, other scientists have formulated different versions of this hypothesis and investigated evidence for and against the biosphere's regulatory mechanisms. Debates about Gaia have been multidisciplinary , drawing participants from climatology, geophysics, chemistry, ecology , and philosophy [5]. These debates may help to launch a new field of research, geophysiology, which concerns itself with large-scale interactions between the Earth's biota, atmosphere, soil, and oceans. Recent and forthcoming books about Gaia contain the ideas of respected scientists and philosophers [6-9], and the Biosphere II project has generated considerable interest among the general public in the stability of closed biospheres [10]. Gaia has evolved from a "fringe science" into a fullfledged research program. While many scientists have jumped on the Gaia bandwagon, others The author is grateful to Connie Barlow and Tyler Volk for their helpful comments and criticism. *Department of Philosophy, University of Wyoming, Laramie, Wyoming 82071-3392.© 1992 by The University of Chicago. AU rights reserved. 003 1-5982/92/3504-0800$0 1 .00 572 David B. Resnik ¦ Fanciful Notion to Research Program have been more skeptical. Scientists such as Walker, Hays, and Kasting have argued that the evolution of the Earth's climate can be explained through inorganic mechanisms [H]. Kirchner has argued that there are many versions of the Gaia hypothesis, and that most of these versions are untestable or false [12]. One question that troubles many Gaia critics is whether we should call the Earth's biosphere a "living organism," or even a "self-regulatory system," except in some metaphorical sense. The purpose of this paper is to assess the Gaia hypothesis from the perspective of the philosophy of science. Is the Gaia hypothesis testable or fruitful? Does it have explanatory or predictive power? Is Gaia an independent, existing thing, or a process? Does Gaia have any important social/political implications? This article will try to answer these and other related questions in an attempt to help clarify the Gaia debate. Defining the Gaia Hypothesis The Gaia hypothesis has undergone many changes and revisions since it was formulated by Lovelock and Margulis. Different versions of the Gaia hypothesis have been proposed by Lovelock [2], Margulis [3], Watson and Lovelock [13], and Barlow and Volk [14]. The basic insight shared by each of these versions of the Gaia hypothesis is that organic evolution has led to the formation of a biocybernetic system in which human beings arose. Given this evolutionary setting, one may then ask whether we are altering the Earth in such a way that other species in the system cannot overcome our unbalancing effects. Kirchner distinguishes between five different versions of the Gaia hypothesis, each of which has been defended by some member of the Gaia community [12]. According to Kirchner, many versions of this hypothesis are either false, untestable, or internally contradictory [12]. Kirchner also points out that it is important to specify what we mean by the Gaia hypothesis, otherwise the whole debate about Gaia will suffer from needless ambiguity and confusion. Indeed, opponents and critics of Gaia will be talking past one another if they are not even addressing the same hypothesis. Since Kirchner has already undermined several versions of the Gaia hypothesis, I will focus on three versions mentioned by Kirchner that may offer some promise [12]: 1.Influential Gaia. The biota substantially influences certain aspects of the abiotic world (i.e., the oceans...