Origins of Hierarchical Logical Reasoning.

Hierarchical cognitive mechanisms underlie sophisticated behaviors, including language, music, mathematics, tool-use, and theory of mind. The origins of hierarchical logical reasoning have long been, and continue to be, an important puzzle for cognitive science. Prior approaches to hierarchical logical reasoning have often failed to distinguish between observable hierarchical behavior and unobservable hierarchical cognitive mechanisms. Furthermore, past research has been largely methodologically restricted to passive recognition tasks as compared to active generation tasks that are stronger tests of hierarchical rules. We argue that it is necessary to implement learning studies in humans, non-human species, and machines that are analyzed with formal models comparing the contribution of different cognitive mechanisms implicated in the generation of hierarchical behavior. These studies are critical to advance theories in the domains of recursion, rule-learning, symbolic reasoning, and the potentially uniquely human cognitive origins of hierarchical logical reasoning.

Darwin, Hume, Morgan, and the verae causae of psychology.

Charles Darwin and C. Lloyd Morgan forward two influential principles of cognitive ethological inference that yield conflicting results about the extent of continuity in the cognitive traits of humans and other animals. While these principles have been interpreted as reflecting commitments to different senses of parsimony, in fact, both principles result from the same vera causa inferential strategy, according to which "We ought to admit no more causes of natural things, than such as are both true and sufficient to explain their appearances". Instead, the conflict stems from Darwin's and Morgan's views about the true causes of human psychology. Darwin holds a thoroughly Humean philosophy of the human mind, from which he infers significant continuity between human and animal minds. In contrast, Morgan argues that Humean cognitive mechanisms cannot account for a class of uniquely human behaviors, and therefore, he concludes that there is a significant discontinuity between human and animal cognition. This historical debate is informative for current controversies in comparative psychology.