Do deconstructive ecology and sociobiology undermine Leopold's land ethic?

Environmental Ethics

Volumn 18, Issue 4, 1996, Pages 353-372

  Callicott, J Baird ^a  

^a UNIVERSITY OF NORTH TEXAS   (United States)

Author keywords

[No Author keywords available]

Indexed keywords

EID: 0000223618     PISSN: 01634275     EISSN: None     Source Type: Journal    
DOI: 10.5840/enviroethics19961843     Document Type: Article

References (99)

1. Michael Soulé, "The Social Siege of Nature," in M. Soulé and G. Lease, eds., Reinventing Nature? Responses to Postmodern Deconstruction (Washington: Island Press, 1995), p. 138.
2. It might be called deconstructive ecology because the old master narratives of ecology - organicism, community, ecosystem - are currently being reviled, and there is an apparent contentment with either no organizing paradigm or a plurality of mutually inconsistent organizing paradigms in ecology. See Daniel Simberloff, "A Succession of Paradigms in Ecology: Essentialism to Materialism and Probabilism," Synthese 43 (1980): 3-39.
3. Soulé, "Social Siege," p. 143 (emphasis in original).
4. See Donald Worster, "The Ecology of Order and Chaos," Environmental History Review 14 (1990): 1-18, for an exposé.
5. For a review of the difficulties with the ecosystem and community concepts, see K. S. Shrader-Frechette and E. D. McCoy, Method in Ecology: Strategies for Conservation (Cambridge: Cambridge University Press, 1993).
6. Worster, "Ecology of Order and Chaos," reports that "A survey of recent ecology textbooks shows that the [ecosystem] concept is not even mentioned in one leading work and has a much diminished place in the others" (p. 8). A more sanguine assessment is provided by Frank Benjamin Colley, A History of the Ecosystem Concept in Ecology (New Haven, Conn: Yale University Press, 1994), but even Golley's partisan account reveals the ecosystem concept to be problematic.
7. Worster, "Ecology of Order and Chaos," reports that "A survey of recent ecology textbooks shows that the [ecosystem] concept is not even mentioned in one leading work and has a much diminished place in the others" (p. 8). A more sanguine assessment is provided by Frank Benjamin Colley, A History of the Ecosystem Concept in Ecology (New Haven, Conn: Yale University Press, 1994), but even Golley's partisan account reveals the ecosystem concept to be problematic.
8. A severe blow to the community concept was struck by Margaret B. Davis, "Climatic Instability, Time Lags, and Community Disequilibrium," in J. Diamond and T. J. Case, eds., Community Ecology (New York: Harper and Row, 1984).
9. Daniel Goodman, "The Theory of Diversity-Stability Relationships in Ecology" Quarterly Review of Biology 30 (1975): 237-66, provides a summary of research results through the mid-seventies on the diversity-stability hypothesis. His conclusion drips with sarcasm and contempt: "The diversity-stability hypothesis may have caught the lay conservationists' fancy, not for the allure of its scientific embellishments, but for the more basic appeal of its underlying metaphor. It is the sort of thing that people like, and want, to believe. Thus, though better theories supplant it in scientific usage, we may be certain that the 'hypothesis' will persist for awhile as an element of folk science. Eventually that remnant, too, may vanish in light of discordant facts, and the imagery of this once-scientific hypothesis will recede to a revered position in the popular environmental ethic, where it doubtless will do much good" (p. 261).
10. For a review of the difficulties, see Shrader-Frechette and McCoy, Method in Ecology. For a discussion, see Mark Sagoff, "Fact and Value in Ecological Science," Environmental Ethics 7 (1985): 99-116.
11. For a review of the difficulties, see Shrader-Frechette and McCoy, Method in Ecology. For a discussion, see Mark Sagoff, "Fact and Value in Ecological Science," Environmental Ethics 7 (1985): 99-116.
12. See Daniel Botkin, Discordant Harmonies: A New Ecology for the Twenty-first Century (New York: Oxford University Press, 1990).
13. See Robert May, "Biological Populations with Nonoverlapping Generations: Stable Points, Stable Cycles, and Chaos" Science 186 (1974): 645-47; James Gleik, Chaos: The Making of a New Science (New York: Viking, 1987); H. Degan, A. V. Holden, and L. F. Olsen, Chaos in Biological Systems (New York: Plenum Press, 1987).
14. See Robert May, "Biological Populations with Nonoverlapping Generations: Stable Points, Stable Cycles, and Chaos" Science 186 (1974): 645-47; James Gleik, Chaos: The Making of a New Science (New York: Viking, 1987); H. Degan, A. V. Holden, and L. F. Olsen, Chaos in Biological Systems (New York: Plenum Press, 1987).
15. See Robert May, "Biological Populations with Nonoverlapping Generations: Stable Points, Stable Cycles, and Chaos" Science 186 (1974): 645-47; James Gleik, Chaos: The Making of a New Science (New York: Viking, 1987); H. Degan, A. V. Holden, and L. F. Olsen, Chaos in Biological Systems (New York: Plenum Press, 1987).
16. S. T. A. Pickett and P. S. White, The Ecology of Natural Disturbance and Patch Dynamics (Orlando, Fla.: Academic Press, 1985).
17. For a representative version of the Judeo-Christian Stewardship environmental ethic see Patrick Dobel, "The Judeo-Christian Stewardship Attitude Toward Nature," in Louis P. Pojman, ed., Environmental Ethics: Readings in Theory and Application (Boston; Jones and Bartlett, 1994): 20-24.
18. Paul R. Ehrlich and Anne H. Ehrlich, Extinction: The Causes and Consequences of the Disappearance of Species (New York: Random House, 1981). For a discussion of the redundancy of the species most vulnerable to extinction see David Ehrenfeld, "Why Put a Value on Biodiversity?" in E. O. Wilson, ed., Biodiversity (Washington: National Academy Press, 1988): 212-16. Also see Sagoff, "Fact and Value."
19. Paul R. Ehrlich and Anne H. Ehrlich, Extinction: The Causes and Consequences of the Disappearance of Species (New York: Random House, 1981). For a discussion of the redundancy of the species most vulnerable to extinction see David Ehrenfeld, "Why Put a Value on Biodiversity?" in E. O. Wilson, ed., Biodiversity (Washington: National Academy Press, 1988): 212-16. Also see Sagoff, "Fact and Value."
20. Paul R. Ehrlich and Anne H. Ehrlich, Extinction: The Causes and Consequences of the Disappearance of Species (New York: Random House, 1981). For a discussion of the redundancy of the species most vulnerable to extinction see David Ehrenfeld, "Why Put a Value on Biodiversity?" in E. O. Wilson, ed., Biodiversity (Washington: National Academy Press, 1988): 212-16. Also see Sagoff, "Fact and Value."
21. Paul W. Taylor, Respect for Nature (Princeton, New Jersey: Princeton University Press, 1986).
22. Harley Cahen, "Against the Moral Considerability of Ecosystems," Environmental Ethics 10 (1988): 195-216; Brian K. Steverson, "Ecocentrism and Ecological Modeling," Environmental Ethics 16 (1994): 71-88; and Gary L. Comstock, "Do Agriculturalists Need a New, an Ecocentric Ethic?" Agriculture and Human Values 12 (1995): 2-15, have anticipated me here. Cahen's argument is more applicable to interest-based ecocentrism, such as that advocated by Lawrence Johnson, A Morally Deep World (Cambridge: Cambridge University Press, 1991), than to the communitarian Leopold land ethic. Comstock answers his title question in the negative. I have more to say infra about Steverson's critique of ecocentrism.
23. Harley Cahen, "Against the Moral Considerability of Ecosystems," Environmental Ethics 10 (1988): 195-216; Brian K. Steverson, "Ecocentrism and Ecological Modeling," Environmental Ethics 16 (1994): 71-88; and Gary L. Comstock, "Do Agriculturalists Need a New, an Ecocentric Ethic?" Agriculture and Human Values 12 (1995): 2-15, have anticipated me here. Cahen's argument is more applicable to interest-based ecocentrism, such as that advocated by Lawrence Johnson, A Morally Deep World (Cambridge: Cambridge University Press, 1991), than to the communitarian Leopold land ethic. Comstock answers his title question in the negative. I have more to say infra about Steverson's critique of ecocentrism.
24. Harley Cahen, "Against the Moral Considerability of Ecosystems," Environmental Ethics 10 (1988): 195-216; Brian K. Steverson, "Ecocentrism and Ecological Modeling," Environmental Ethics 16 (1994): 71-88; and Gary L. Comstock, "Do Agriculturalists Need a New, an Ecocentric Ethic?" Agriculture and Human Values 12 (1995): 2-15, have anticipated me here. Cahen's argument is more applicable to interest-based ecocentrism, such as that advocated by Lawrence Johnson, A Morally Deep World (Cambridge: Cambridge University Press, 1991), than to the communitarian Leopold land ethic. Comstock answers his title question in the negative. I have more to say infra about Steverson's critique of ecocentrism.
25. Harley Cahen, "Against the Moral Considerability of Ecosystems," Environmental Ethics 10 (1988): 195-216; Brian K. Steverson, "Ecocentrism and Ecological Modeling," Environmental Ethics 16 (1994): 71-88; and Gary L. Comstock, "Do Agriculturalists Need a New, an Ecocentric Ethic?" Agriculture and Human Values 12 (1995): 2-15, have anticipated me here. Cahen's argument is more applicable to interest-based ecocentrism, such as that advocated by Lawrence Johnson, A Morally Deep World (Cambridge: Cambridge University Press, 1991), than to the communitarian Leopold land ethic. Comstock answers his title question in the negative. I have more to say infra about Steverson's critique of ecocentrism.
26. See J. Baird Callicott, "The Conceptual Foundations of the Land Ethic," in J. Baird Callicott, ed., Companion to A Sand County Almanac: Interpretive and Critical Essays (Madison: University of Wisconsin Press, 1987): 186-217.
27. Charles Darwin, The Descent of Man and Selection in Relation to Sex (New York: Modern Library, n.d.), p. 487.
28. Ibid., pp. 491-92.
29. Aldo Leopold, "The Conservation Ethic," Journal of Forestry 31 (1933), p. 634 (emphasis added to highlight the allusions to Darwin's account in the Descent of Man of the evolutionary origins and cultural development of ethics).
30. One could argue that the revisions - changing biological in the second sentence to ecological and changing biologically in the third sentence to ecologically - were ill-advised. Darwin's account of the origin and evolution of ethics was less an exercise in human ecology than in human evolution, thus it was more generally biological than specifically ecological.
31. Aldo Leopold, A Sand County Almanac and Sketches Here and There (New York: Oxford University Press, 1949), pp. 203-04.
32. Aldo Leopold, "Some Fundamentals of Conservation in the Southwest," Environmental Ethics 1 (1979): 131-41.
33. Arthur Tansley, "The Use and Abuse of Vegetational Concepts and Terms," Ecology 16 (1935): 284-307; Raymond L. Lindeman, "The Trophic-Dynamic Aspect of Ecology," Ecology 23 (1942): 399-418; Eugene Odum, Fundamentals of Ecology, 3d ed. (Philadelphia: Saunders, 1971).
34. Arthur Tansley, "The Use and Abuse of Vegetational Concepts and Terms," Ecology 16 (1935): 284-307; Raymond L. Lindeman, "The Trophic-Dynamic Aspect of Ecology," Ecology 23 (1942): 399-418; Eugene Odum, Fundamentals of Ecology, 3d ed. (Philadelphia: Saunders, 1971).
35. Arthur Tansley, "The Use and Abuse of Vegetational Concepts and Terms," Ecology 16 (1935): 284-307; Raymond L. Lindeman, "The Trophic-Dynamic Aspect of Ecology," Ecology 23 (1942): 399-418; Eugene Odum, Fundamentals of Ecology, 3d ed. (Philadelphia: Saunders, 1971).
36. Leopold, Sand County, p. 214; "Some Fundamentals," p. 139. The ecosystem paradigm is grounded in physics, not biology, and mechanism had dominated thought in physics since the seventeenth century. Hence, mechanism may be, some have argued, consistent with, if not implied by, the ecosystem paradigm: for a notable example, see Botkin, Discordant Harmonies; for an overview, see Stephen Bocking, "Visions of Nature and Society: A History of the Ecosystem Concept," Alternatives 20, no. 3 (1994): 12-18.
37. Leopold, Sand County, p. 214; "Some Fundamentals," p. 139. The ecosystem paradigm is grounded in physics, not biology, and mechanism had dominated thought in physics since the seventeenth century. Hence, mechanism may be, some have argued, consistent with, if not implied by, the ecosystem paradigm: for a notable example, see Botkin, Discordant Harmonies; for an overview, see Stephen Bocking, "Visions of Nature and Society: A History of the Ecosystem Concept," Alternatives 20, no. 3 (1994): 12-18.
38. Leopold, Sand County, p. 214; "Some Fundamentals," p. 139. The ecosystem paradigm is grounded in physics, not biology, and mechanism had dominated thought in physics since the seventeenth century. Hence, mechanism may be, some have argued, consistent with, if not implied by, the ecosystem paradigm: for a notable example, see Botkin, Discordant Harmonies; for an overview, see Stephen Bocking, "Visions of Nature and Society: A History of the Ecosystem Concept," Alternatives 20, no. 3 (1994): 12-18.
39. Leopold, Sand County, p. 214; "Some Fundamentals," p. 139. The ecosystem paradigm is grounded in physics, not biology, and mechanism had dominated thought in physics since the seventeenth century. Hence, mechanism may be, some have argued, consistent with, if not implied by, the ecosystem paradigm: for a notable example, see Botkin, Discordant Harmonies; for an overview, see Stephen Bocking, "Visions of Nature and Society: A History of the Ecosystem Concept," Alternatives 20, no. 3 (1994): 12-18.
40. Leopold, Sand County, p. 214.
41. Aldo Leopold, "A Biotic View of Land" Journal of Forestry 37 (1939): 728. Substantial portions of this essay were incorporated into "The Land Ethic," as were substantial portions of "The Conservation Ethic." See Curt Meine, "Building 'The Land Ethic,'" in J. Baird Callicott, ed., Companion to A Sand County Almanac (Madison: University of Wisconsin Press, 1987) pp 172-85.
42. Aldo Leopold, "A Biotic View of Land" Journal of Forestry 37 (1939): 728. Substantial portions of this essay were incorporated into "The Land Ethic," as were substantial portions of "The Conservation Ethic." See Curt Meine, "Building 'The Land Ethic,'" in J. Baird Callicott, ed., Companion to A Sand County Almanac (Madison: University of Wisconsin Press, 1987) pp 172-85.
43. Leopold, Sand County, pp. 216-17.
44. Ibid., p. 210.
45. See Stuart Pimm, The Balance of Nature? (Chicago: University of Chicago Press, 1991) for a comprehensive discussion of the principal varieties of stability - persistence, resistance, and resilience. Gordon Orians, "Diversity, Stability, and Maturity in Natural Systems" in H. A. Mooney and J. A. Drake, eds., Ecology of Biological Invasions of North America and Hawaii (New York: Springer-Verlag, 1975): 139-50, distinguishes no fewer than seven varieties of stability.
46. See Stuart Pimm, The Balance of Nature? (Chicago: University of Chicago Press, 1991) for a comprehensive discussion of the principal varieties of stability - persistence, resistance, and resilience. Gordon Orians, "Diversity, Stability, and Maturity in Natural Systems" in H. A. Mooney and J. A. Drake, eds., Ecology of Biological Invasions of North America and Hawaii (New York: Springer-Verlag, 1975): 139-50, distinguishes no fewer than seven varieties of stability.
47. Aldo Leopold, "Conservation: In Whole or in Part?" in Susan L. Flader and J. Baird Callicott, eds., The River of the Mother of God and Other Essays by Aldo Leopold (Madison: University of Wisconsin Press, 1991), p. 312.
48. Ibid., p. 315 (emphasis added).
49. Linda B. Brubaker, "Vegetation History and Anticipating Future Vegetation Change," in J. K. Agee, Ecosystem Management for Parks and Wilderness (Seattle: University of Washington Press, 1988), p. 41.
50. A particularly warm endorsement of reductionism and the individualistic paradigm in ecology is Simberloff, "A Succession of Paradigms in Ecology."
51. See Eugene C. Hargrove, Foundations of Environmental Ethics (Englewood Cliffs, New Jersey: Prentice-Hall, 1989); Mark Sagoff, The Economy of the Earth (Cambridge: Cambridge University Press, 1988).
52. See Eugene C. Hargrove, Foundations of Environmental Ethics (Englewood Cliffs, New Jersey: Prentice-Hall, 1989); Mark Sagoff, The Economy of the Earth (Cambridge: Cambridge University Press, 1988).
53. Goodman, "The Theory of Diversity-Stability Relationships," is incautiously dismissive.
54. Soule, "The Social Siege of Nature" (p. 143) begins his debunking of the community "myth" with the word certainly.
55. Goodman, "The Theory of Diversity-Stability Relationships."
56. Ibid.
57. David Tilman and John A. Downing, "Biodiversity and Stability in Grasslands," Nature 367 (1994): 363.
58. Ibid.
59. Luna B. Leopold, ed., Round River: From the Journals of Aldo Leopold (New York: Oxford University Press, 1953), pp. 146-47.
60. Soulé, "Social Siege," thus confidently writes, "There is now no question that all life on earth evolved from a common ancestor. The genetic material and the codes embedded within it reveal that every living kind of plant and animal owes its existence to a single-celled ancestor that evolved some three and a half billion years ago. All species are kin" (p. 142, emphasis in original).
61. See James Rachels, Created From Animals (New York: Oxford University Press, 1990). Paul W. Taylor, "The Ethics of Respect for Nature" Environmental Ethics 3 (1981): 197-218, also regards evolutionary kinship to be foundational to his biocentrism.
62. See James Rachels, Created From Animals (New York: Oxford University Press, 1990). Paul W. Taylor, "The Ethics of Respect for Nature" Environmental Ethics 3 (1981): 197-218, also regards evolutionary kinship to be foundational to his biocentrism.
63. Leopold, Sand County, p. 109.
64. For a probative discussion, see John Chandler, "Ethical Philosophy," in M. Maxwell, ed., The Sociobiological Imagination (Albany: SUNY, 1991). Among reductive proponents Chandler cites Richard Dawkins, The Selfish Gene (New York: Oxford University Press, 1976); Edward O. Wilson, On Human Nature (Cambridge, Mass.: Harvard University Press, 1978); and Richard D. Alexander, The Biology of Moral Systems (Hawthorn, N.Y.: Aldine, 1987). Among critics, Chandler cites Philip Kitchner, Vaulting Ambition: Sociobiology and the Quest for Human Nature (Cambridge, Mass.: MiT Press, 1985).
65. For a probative discussion, see John Chandler, "Ethical Philosophy," in M. Maxwell, ed., The Sociobiological Imagination (Albany: SUNY, 1991). Among reductive proponents Chandler cites Richard Dawkins, The Selfish Gene (New York: Oxford University Press, 1976); Edward O. Wilson, On Human Nature (Cambridge, Mass.: Harvard University Press, 1978); and Richard D. Alexander, The Biology of Moral Systems (Hawthorn, N.Y.: Aldine, 1987). Among critics, Chandler cites Philip Kitchner, Vaulting Ambition: Sociobiology and the Quest for Human Nature (Cambridge, Mass.: MiT Press, 1985).
66. For a probative discussion, see John Chandler, "Ethical Philosophy," in M. Maxwell, ed., The Sociobiological Imagination (Albany: SUNY, 1991). Among reductive proponents Chandler cites Richard Dawkins, The Selfish Gene (New York: Oxford University Press, 1976); Edward O. Wilson, On Human Nature (Cambridge, Mass.: Harvard University Press, 1978); and Richard D. Alexander, The Biology of Moral Systems (Hawthorn, N.Y.: Aldine, 1987). Among critics, Chandler cites Philip Kitchner, Vaulting Ambition: Sociobiology and the Quest for Human Nature (Cambridge, Mass.: MiT Press, 1985).
67. For a probative discussion, see John Chandler, "Ethical Philosophy," in M. Maxwell, ed., The Sociobiological Imagination (Albany: SUNY, 1991). Among reductive proponents Chandler cites Richard Dawkins, The Selfish Gene (New York: Oxford University Press, 1976); Edward O. Wilson, On Human Nature (Cambridge, Mass.: Harvard University Press, 1978); and Richard D. Alexander, The Biology of Moral Systems (Hawthorn, N.Y.: Aldine, 1987). Among critics, Chandler cites Philip Kitchner, Vaulting Ambition: Sociobiology and the Quest for Human Nature (Cambridge, Mass.: MiT Press, 1985).
68. For a probative discussion, see John Chandler, "Ethical Philosophy," in M. Maxwell, ed., The Sociobiological Imagination (Albany: SUNY, 1991). Among reductive proponents Chandler cites Richard Dawkins, The Selfish Gene (New York: Oxford University Press, 1976); Edward O. Wilson, On Human Nature (Cambridge, Mass.: Harvard University Press, 1978); and Richard D. Alexander, The Biology of Moral Systems (Hawthorn, N.Y.: Aldine, 1987). Among critics, Chandler cites Philip Kitchner, Vaulting Ambition: Sociobiology and the Quest for Human Nature (Cambridge, Mass.: MiT Press, 1985).
69. According to Edward O. Wilson, Sociobiology: The New Synthesis (Cambridge, Mass.: The Belknap Press of Harvard University, 1975), "the central theoretical problem of Sociobiology [is] how can altruism, which by definition reduces personal fitness, possibly evolve by natural selection?" (p. 3).
70. See W. D. Hamilton, "The Genetical Theory of Social Behaviour," Journal of Theoretical Biology 7 (1964): 1-52.
71. We are, of course, indebted for this infelicitous phrase to Dawkins, The Selfish Gene.
72. Warwick Fox, Toward a Transpersonal Ecology (Boston: Shamballa, 1990), p. 264.
73. Ibid.
74. Peter Singer, The Expanding Circle: Ethics and Sociobiology (New York: Ferrar, Strauss, and Giroux, 1982).
75. Garret Hardin provides an illuminating discussion in "Discriminating Altruisms," Zygon 17 (1982): 163-86.
76. In trying to repair some of the damage done to environmentalism by deconstructive ecology, Worster, in the second edition of Nature's Economy, evokes "the principle of interdependency": "No organism or species of organism has any chance of surviving without the aid of others" (p. 429).
77. See Lovelock, Ages of Gaia.
78. John Passmore, Man's Responsibility for Nature: Ecological Problems and Western Traditions (New York: Scribner's, 1974), p. 116. Passmore intends expressly to criticize the Leopold land ethic with his bacteria counter-example to ethics-generating interspecies community membership.
79. Lynn Margulis and Dorion Sagan, Microcosmos (New York: Simon and Schuster, 1986).
80. Steverson, "Ecocentrism," p. 81.
81. Paul R. Ehrlich, "The Limits to Substitution: Meta-resource Depletion and a New Economic-ecological Paradigm," Ecological Economics 1 (1989): 9-16.
82. Steverson, "Ecocentrism," pp. 81-82.
83. Ibid.
84. See Shrader-Frechette and McCoy, Method in Ecology.
85. Lindeman, "The Trophic-Dynamic Aspect of Ecology."
86. F. H. Bormann and G. E. Likens, "Nutrient Cycling," Science 155 (1967): 424-29.
87. For a discussion, see Golley, The Ecosystem Concept in Ecology.
88. See R. V. O'Neill, D. L. DeAngelis, J. B. Waide, and T. F. H. Allen, A Hierarchical Concept of Ecosystems (Princeton: Princeton University Press, 1986). For an application of hierarchy theory in systems ecology to environmental ethics, see Stanley N. and Barbara M. Salthe, "Ecosystem Moral Considerability: A Reply to Cahen," Environmental Ethics 11 (1989): 355-61.
89. See R. V. O'Neill, D. L. DeAngelis, J. B. Waide, and T. F. H. Allen, A Hierarchical Concept of Ecosystems (Princeton: Princeton University Press, 1986). For an application of hierarchy theory in systems ecology to environmental ethics, see Stanley N. and Barbara M. Salthe, "Ecosystem Moral Considerability: A Reply to Cahen," Environmental Ethics 11 (1989): 355-61.
90. T. F. H. Allen and T. W. Hoekstra, Toward a Unified Ecology (New York: Columbia University Press, 1992), pp. 94, 98-100.
91. Leopold, Sand County, p. 204.
92. Others include most of the authors represented in Wilson, Biodiversity.
93. D. M. Raup and J. J. Sepkoski, "Periodicity of Extinctions in the Geologic Past," Proceedings of the National Academy of Sciences USA 81 (1984): 801-05. For a discussion of causes of these mass extinction events, see D. M. Raup, Extinction: Bad Genes or Bad Luck? (New York: W. W. Norton, 1991).
94. D. M. Raup and J. J. Sepkoski, "Periodicity of Extinctions in the Geologic Past," Proceedings of the National Academy of Sciences USA 81 (1984): 801-05. For a discussion of causes of these mass extinction events, see D. M. Raup, Extinction: Bad Genes or Bad Luck? (New York: W. W. Norton, 1991).
95. See Stephen H. Schneider, Global Warming: Are We Entering the Greenhouse Century? (San Francisco: Sierra Club Books, 1989).
96. Pickett and White, Ecology of Natural Disturbance.
97. S. T. A. Pickett and Richard S. Ostfeld, "The Shifting Paradigm in Ecology," in R. L. Knight and S. F. Bates, eds., A New Century for Natural Resources Management (Washington: Island Press, 1995), pp. 273-74.
98. Leopold, Sand County, p. 217.
99. Tom Birch and Holmes Rolston (personal communications) both point out that this reformulation of the summary moral maxim of the land ethic is incomplete (at best). I agree with these reservations. Yet, a summary moral maxim has to be general and pithy to be a summary moral maxim-and general and pithy statements are necessarily incomplete.