Did Darwin Write the Origin Backwards: Philosophical Essays on Darwin's Theory

238 Pages·2010·3.04 MB·English

by  Elliott Sober

Published 2011 by Prometheus Books Did Darwin Write the Origin Backwards? Philosophical Essays on
Darwin's Theory. Copyright © 2011 by Elliott Sober. All rights reserved. No part of this publication may be
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PREFACE
ACKNOWLEDGMENTS
1. DID DARWIN WRITE THE ORIGIN BACKWARDS?
1.1. What Is Darwin's Theory?
1.2. Common Ancestry
1.3. Darwin's Principle
1.4. Exceptions to Darwin's Principle
1.5. Causal and Evidential Orderings
1.6. Using Common Ancestry to Think about Natural Selection
1.7. Tree Thinking
2. DARWIN AND GROUP SELECTION
2.1. Back to the 60s
2.2. Human Morality
2.3. The Honeybee's Barbed Stinger
2.4. The Risk of Anachronism
2.5. More on Darwin on Morality
2.6. Sterile Workers in the Social Insects
2.7. Darwin's Disagreement with Wallace about Hybrid Sterility
2.8. Darwin's General View of Group Selection
3. SEX RATIO THEORY—DARWIN, BEFORE, AND AFTER
3.1. Arbuthnot on “the exact balance that is maintained between the
numbers of men and women … that the Species may never fail, nor
perish
3.2. Bernoulli on 18/35
3.3. DeMoivre—“if we blind not ourselves with metaphysical dust”
3.4. Darwin's Argument from Monogamy, and His Retraction
3.5. Düsing's Model—Monogamy Drops Out
3.6. Fisher and Parental Expenditure
3.7. Hamilton—Group and Individual Selection
3.8. Sex Ratio as a Test Case
Appendix: An Example of Hamiltonian Sex Ratio Evolution in Group with
Two Foundresses
4. DARWIN AND NATURALISM
4.1. Darwin's Discussions of God
4.2. Refining Methodological Naturalism
4.3. Why Evolutionary Theory Does Not Rule Out an Intervening God
4.4. Should Scientific Theories Talk Only about What Exists in Nature?
4.5. Are All Claims about the Supernatural Untestable?
4.6. Is Violating Methodological Naturalism a Science-Stopper?
4.7. If Numbers, Why Not God?
4.8. Concluding Comments
5. POSTSCRIPT
5.1. Second Thoughts about Cladistic Parsimony and the Test of Adaptive
Hypotheses
5.2. More on Units of Selection
5.3. Evolutionary Theory and the Reality of Macroprobabilities
NOTES
REFERENCES
INDEX
T
his book is a mixture of historical attention to Darwin's texts and philosophical
attention to questions that arise in Darwin's theory and in the evolutionary
biology that his theory initiated. This is not a work of hagiography, but neither
does it treat Darwin's work as an object of merely antiquarian curiosity.
The first chapter examines a simple but fundamental question about how
Darwin organized his argument in the Origin of Species. The two big ideas in
Darwin's theory are common ancestry and natural selection. Why did Darwin put
selection first and foremost in the Origin and allow his views about common
ancestry to emerge only gradually and as a secondary theme? This is a question
about Darwin's rhetoric— the strategy he used to lay out his argument. The
question becomes pressing when we look at Darwin's logic—at how the
elements of his theory are related to each other and to the evidence he assembles.
Chapter 2 discusses Darwin's views about group selection. My exposition
begins in the 1960s, then moves to the present, and then time travels back to
1859. The idea that traits evolve because they are good for the group was
criticized in the 1960s, not just for being factually mistaken, but for embodying a
kind of mushy thinking that is fundamentally at odds with the logic that Darwin's
theory requires. The 1960s are very much alive today, in that many biologists
still regard the concept of group selection as a snare and a delusion. However, a
countermovement has arisen since the 1960s called multilevel selection theory,
according to which selection acts at multiple levels, including the level of the
group. After briefly outlining the 1960s attack on group selection and the
concept's subsequent revival, I examine Darwin's views on the subject. I do so
by analyzing his reasoning about four examples: human morality, the barbed
stinger of the honeybee, neuter workers in species of social insect, and the
sterility of many interspecies hybrids. I then consider Darwin's general position
on the role of group selection in evolution.
Chapter 3 is a selective history of attempts to explain sex ratio. The problem
arises in connection with every sexual species. Why, for example, do human
populations have approximately equal numbers of males and females? This
question was addressed in the eighteenth century by three important probabilists
who understood it in terms of the design argument for the existence of God. A
century later, Darwin tried to use his theory of natural selection to solve the
problem, but he gave up in frustration, hoping that the evolutionary biology of
the future would do better. His hope came true. Sex ratio is an interesting case
study, since it is a problem at which both intelligent-design theorists and
evolutionary biologists have had a go. Evolutionary biology has succeeded
where creationism has failed—in formulating hypotheses that make predictions
about future observations rather than simply being able to accommodate past
ones.
Chapter 4 concerns methodological naturalism, a philosophical position that
is absolutely central to modern science. Methodological naturalism says that
science should not make claims about God. I begin the chapter by describing
what Darwin says about God in the Origin. Do Darwin's remarks represent a
violation of methodological naturalism? Answering this question leads to a
refinement of what this ism means. I then explore how the theory of evolution is
related to three theistic positions—creationism, deism, and the view that
evolutionary theory is true but incomplete because God's interventions in nature
sometimes supplement the causes that the theory describes. It is obvious that the
theory is incompatible with creationism, and it is a familiar point that
evolutionary theory is logically compatible with deism. It is less often
recognized that evolutionary theory also is compatible with some interventionist
theologies. I defend this thesis of compatibility by clarifying the biological claim
that mutations are “undirected.” I do so, not because I want to endorse the thesis
that God intervenes in nature, but because I think it important that theists and
atheists both recognize that evolutionary theory really is neutral on this question.
I then consider three defenses that have been made of methodological naturalism
—that science, by definition, is an enterprise that excludes claims about
supernatural deities; that claims about the supernatural are untestable; and that
including such claims in scientific theories would bring science to a stop. After
criticizing these arguments, I provide a more modest defense of methodological
naturalism.
In the postscript (chapter 5), I revisit some themes introduced earlier and
expand on them. This chapter is more technical than the ones that come before,
and the focus is on contemporary evolutionary theory, not on Darwin. From
chapter 1, there is the use of a principle of parsimony to reconstruct the character
states of ancestors and the question of how hypotheses about adaptation can be
tested. Drawing on material from chapter 2, on the units of selection, I discuss
conventionalism versus realism as well as the difference between units of
selection and units of adaptation. And, further developing some ideas from
chapter 4, I consider whether the probabilities discussed in evolutionary theory
describe objective matters of fact.
Madison, Wisconsin
January 2011
A
number of individuals read this manuscript as it developed and gave me useful
comments. Others were kind enough to answer specific questions that I put to
them as I was writing. I very much appreciate the help of Michael Antolin,
Matthew Barker, John Basl, David Baum, Glenn Branch, John Hedley Brooke,
Hayley Clatterbuck, James Crow, Niles Eldredge, Marc Ereshefsky, Joshua
Filler, Jean Gayon, Michael Goldsby, Daniel Hausman, Casey Helgeson,
Jonathan Hodge, Robert Jeanne, Philip Kitcher, David Kohn, Matthew Kopec,
Egbert Leigh, Richard Lewontin, David Miller, Gene Miller, Gregory Novack,
Ronald Numbers, Samir Okasha, Alvin Plantinga, Gregory Radick, Robert
Richards, Alexander Rosenberg, Michael Ruse, Sam Schweber, Larry Shapiro,
Frank Sulloway, Mark Taylor, Michael Titelbaum, Peter Vranas, Paul White, and
David Sloan Wilson.
My debts go deeper into the past, in that there are many scholars who helped
me as I worked on previous publications that are in varying degrees ancestral to
the present book. In addition to the individuals listed above, I want to thank
David Bordwell, Robert Brandon, Jeremy Butterfield, Juan Comesaña, James
Cortada, Anthony Edwards, Branden Fitelson, Patrick Forber, Malcolm Forster,
Clark Glymour, Christopher Hitchcock, Thomas Hofweber, Marc Lange, John
Lazarus, Stephen Leeds, Gerald McKenna, Hugh Mellor, Bradley Monton,
Steven Orzack, Ann Pollock, John Roberts, Robert Russell, Carolina Sartorio,
Armin Schulz, Christopher Stephens, William Stoeger, Michael Strevens, Mark
Taylor, Joel Velasco, Howard Weinbrot, James L. Wood, Jim Woodward, and Ed
Zalta.
I wrote this book while holding a William F. Vilas Research Professorship. I
am grateful to the William F. Vilas Trust for this support.
Chapters 1 and 3 of this book are revised and expanded versions of articles I
have published (Sober 2007a, 2009a). Two parts of chapter 5 draw material from
forthcoming articles (Sober 2010b, 2010c; Sober and Wilson 2011). Chapters 2
and 4 appear here for the first time.