Theories that link evolution with moral progress claim to illuminate changes in values in many different cultures over long stretches of time. In some such theories, the evolution of ethics is taken to be part of a cosmic process that encompasses the formation of galaxies and the emergence of life. The scope of a theory may include every human society that has ever existed, and often those of nonhuman animals as well. Yet the values these theories aim to explain and defend are always those of the time and place in which the theory has been created, while the view of moral progress they invoke is that which currently prevails in the section of society occupied by the theorist. The version produced by Allen Buchanan and Russell Powell in The Evolution of Moral Progress is no exception.
They characterize their theory as “biocultural” because it presents an “evolutionary model of moral psychological development” of an individual that underpins the possibility of moral progress in a society. Evolution “has produced ‘adaptively plastic’ moral psychological mechanisms” that act differently in different environments. For example, if one grows up in an environment in which resources are scarce, cooperation with others may be necessary to one’s survival to a greater degree than it would be in a place where resources are more plentiful. As a result, a society that develops in deprivation may value collective effort and equal distribution of resources in order to ensure the well-being of the greatest number of people. By contrast, societies in less punishing areas may value individualism or family ties over a broader sense of communal identity.
Buchanan and Powell focus on “one especially important type of moral progress: gains in what we will refer to as ‘moral inclusivity’ (‘inclusivity’ for short),” which “should include provisions for avoiding or at least minimizing racial, gender, class, and ethnonational prejudice and other forms of parochialism.” In contrast, exclusivist norms restrict moral concern to members of a group to which an individual belongs. Spelling out their theory, they write:
Our central hypothesis is that exclusivist morality is…the result of an adaptively plastic “toggle” that is keyed in to cues of out-group threat that are detected in the environment in which individuals and cultures evolve together. More precisely, exclusivist moral response is a conditionally expressed trait that develops only when cues that were in the past reliably correlated with out-group predation, exploitation, competition for resources, and disease transmission are detected.
In other words, moral exclusivity arises from evolutionary adaptations that aided survival at times in prehistory when outsiders—as rivals for territory and food or as carriers of communicable illness—may have posed a serious threat. Even though humans no longer face a primal struggle over resources, modern events…
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