Elliott Sober

Reintroducing group selection to the human behavioral sciences

In both biology and the human sciences, social groups are sometimes treated as adaptive units whose organization cannot be reduced to individual interactions. This group-level view is opposed by a more individualistic one that treats social organization as a byproduct of self-interest. According to biologists, group-level adaptations can evolve only by a process of natural selection at the group level. Most biologists rejected group selection as an important evolutionary force during the 1960s and 1970s but a positive literature began to grow during the 1970s and is rapidly expanding today. We review this recent literature and its implications for human evolutionary biology. We show that the rejection of group selection was based on a misplaced emphasis on genes as “replicators” which is in fact irrelevant to the question of whether groups can be like individuals in their functional organization. The fundamental question is whether social groups and other higher-level entities can be “vehicles” of selection. When this elementary fact is recognized, group selection emerges as an important force in nature and what seem to be competing theories, such as kin selection and reciprocity, reappear as special cases of group selection. The result is a unified theory of natural selection that operates on a nested hierarchy of units. The vehicle-based theory makes it clear that group selection is an important force to consider in human evolution. Humans can facultatively span the full range from self-interested individuals to “organs” of group-level “organisms.” Human behavior not only reflects the balance between levels of selection but it can also alter the balance through the construction of social structures that have the effect of reducing fitness differences within groups, concentrating natural selection (and functional organization) at the group level. These social structures and the cognitive abilities that produce them allow group selection to be important even among large groups of unrelated individuals.

How to Tell When Simpler, More Unified, or Less Ad Hoc Theories will Provide More Accurate Predictions

Traditional analyses of the curve fitting problem maintain that the data do not indicate what form the fitted curve should take. Rather, this issue is said to be settled by prior probabilities, by simplicity, or by a background theory. In this paper, we describe a result due to Akaike [1973], which shows how the data can underwrite an inference concerning the curves form based on an estimate of how predictively accurate it will be. We argue that this approach throws light on the theoretical virtues of parsimoniousness, unification, and non ad hocness, on the dispute about Bayesianism, and on empiricism and scientific realism.

OPTIMALITY MODELS AND THE TEST OF ADAPTATIONISM

The use of optimality models in the investigation of adaptation remains controversial. Critics charge that advocates of the optimality approach assume that the traits they analyze are optimal. Advocates of the approach deny this but admit to assuming that the traits have adaptive explanations. This controversy is part of the ongoing debate about adaptationism. We believe that this controversy remains unresolved in part because of ambiguity in the definition of adaptationism. In this article, we clarify the thesis of adaptationism, show how the structure of optimality models relates to that thesis, and describe how the thesis of adaptationism is testable. In addition, we describe the types of analyses that are essential to a test of an optimality model if the optimality of the trait is to be assessed and if assessments of the success of specific models are to contribute to a test of adaptationism. These analyses allow one to distinguish between the hypothesis that natural selection has had some influence or an important influence on a trait and the hypothesis that the trait is optimal. At present, to our knowledge, there are only two sets of studies in evolutionary biology in which this critical distinction has been made.

Evidence and Evolution: The Logic Behind the Science

Preface 1. Evidence 2. Intelligent design 3. Natural selection 4. Common ancestry Conclusion References Index.

The Multiple Realizability Argument Against Reductionism

Reductionism is often understood to include two theses: (1) every singular occurrence that the special sciences can explain also can be explained by physics; (2) every law in a higher-level science can be explained by physics. These claims are widely supposed to have been refuted by the multiple realizability argument, formulated by Putnam (1967, 1975) and Fodor (1968, 1975). The present paper criticizes the argument and identifies a reductionistic thesis that follows from one of the arguments premises.

Probabilistic Causality and the Question of Transitivity

After clarifying the probabilistic conception of causality suggested by Good (1961-2), Suppes (1970), Cartwright (1979), and Skyrms (1980), we prove a sufficient condition for transitivity of causal chains. The bearing of these considerations on the units of selection problem in evolutionary theory and on the Newcomb paradox in decision theory is then discussed.

Prediction Versus Accommodation and the Risk of Overfitting

When a scientist uses an observation to formulate a theory, it is no surprise that the resulting theory accurately captures that observation. However, when the theory makes a novel prediction—when it predicts an observation that was not used in its formulation—this seems to provide more substantial confirmation of the theory. This paper presents a new approach to the vexed problem of understanding the epistemic difference between prediction and accommodation. In fact, there are several problems that need to be disentangled; in all of them, the key is the concept of overfitting. We float the hypothesis that accommodation is a defective methodology only when the methods used to accommodate the data fail to guard against the risk of overfitting. We connect our analysis with the proposals that other philosophers have made. We also discuss its bearing on the conflict between instrumentalism and scientific realism. 1. Introduction2. Predictivisms—a taxonomy3. Observations4. Formulating the problem5. What might Annie be doing wrong?6. Solutions7. Observations explained8. Mayo on severe tests9. The miracle argument and scientific realism10. Concluding comments Introduction Predictivisms—a taxonomy Observations Formulating the problem What might Annie be doing wrong? Solutions Observations explained Mayo on severe tests The miracle argument and scientific realism Concluding comments

A Critical Review of Philosophical Work on the Units of Selection Problem

The evolutionary problem of the units of selection has elicited a good deal of conceptual work from philosophers. We review this work to determine where the issues now stand.

The evolution of rationality

• . . our concrete mental operations are indeed adaptations to the mode of life in which we had to compete for survival a long, long, time before science. As such we are saddled with them, just as we are with our organs of locomotion and our eyes and ears. But in science we can transcend them, as electronics t ranscends our sense organs. Why, then, do the formal operations of the mind carry us so much further? Were those abilities not also matters of biological evolution? tf they, too, evolved to let us get along in the cave, how can it be that they permit us to obtain deep insights into cosmology, elementary particles, molecular genetics, number theory? To this question I have no answer.

The Principle of Parsimony

The principle of parsimony has typically been described and defended as if it were a deletion rule, counseling agnosticism. Ockham, followed by those after him who liked the razor to which he gave his name, says that a hypothesis should not be asserted, or an entity postulated, if it is not needed to explain anything (Boehner [1957]). The razor slices away; it tells us to remove what is unnecessary. Modern justifications of parsimoniousness have presupposed this formulation of the principle, and have sought to justify it on grounds of probability. Both Russell ([1951], pp. 148, 155; [1959], pp. 71, 265, 267-9) and Quine [1966] recognise that removing an existential claim from a theoretical system has the effect of raising the probability of what remains. This is simply because a conjunction must have a lower probability than either conjunct, provided that the conjuncts are mutually independent. This agnostic version of the razor, although it is neat in both its simple formulation and its limpid rationale, is mistaken. If we base our characterisation of the razor on what scientists actually achieve when they take it in hand, we must grant that the razor is not purely negative in its effects. One of the advantages which special relativity is supposed to have over Lorentzs theory is its parsimoniousness with respect to the aether. But this parsimoniousness does not consist in the fact that special relativity is silent on the question of the aethers existence; rather, the theory implies that there is no such thing (Einstein [1952], Schaffner [1970]). A recent controversy in evolutionary theory exemplifies the same pattern of thinking. We would have a reason to think that group selection does not exist, if every adaptation could be accounted for by way of individual selection alone (Williams [1966], Lewontin [1970]). And similarly, for Helmholtzs advocacy of empirism in the theory of visual perception: one reason for thinking that the mind is endowed with relatively few innate structures is that the minimal postulates of empirism suffice to explain (Helmholtz [1963], Hatfield [1979]). In these cases, and elsewhere in science, the dispensability of an existence claim is grounds for its denial. The principle of parsimony counsels that toe should hypothesise that an entity does not exist, if its postulation is to no explanatory point. Agnostic formulations of the methodological maxim belie the way in which the razor is employed to