Hume on Nonhuman Animals, Causal Reasoning, and General Thoughts

In both the Treatise and the Enquiry , as a naturalist philosopher Hume is committed to recognizing continuity between humans’ and other animals’ cognitive capacities. In particular, Hume maintains that humans share with other intelligent animals the basic psychological mechanism that underlies their capacities for causal reasoning. In this article, I will address the question whether Hume’s philosophical system can coherently attribute to animals the ability to engage in causal reasoning as he intends. First, I formulate an apparent problem for Hume that his views on causal reasoning and general thinking may seem to yield the following inconsistent triad: (1) causal reasoning requires general thinking; (2) general thinking requires language; (3) nonhuman animals lack language but can engage in causal reasoning. Then, I will develop a Humean solution to the problem by distinguishing two kinds of general thinking, which I call “level‐1” and “level‐2” general thinking, respectively. Level‐1 general thinking does not require language and must play the foundational role in Hume’s account of causal reasoning, as well as his account of language acquisition. Level‐2 general thinking, on the other hand, requires language, and it presupposes the capacity for level‐1 general thinking in several important ways.