The Dual Account of Reason and the Spirit of Philosophy in Hume's Treatise

The purpose of this essay is to contribute to the understanding of Hume’s account of the faculty of reason and to examine some implications for interpreting the broader arc of his philosophy. I argue that Hume develops his thinking about reason dialectically in Book I of the Treatise by creating a reflective dynamic between two different concepts of reason. The first concept of reason (reason1) is a narrow faculty that operates on ideas via intuition and demonstration. The second concept (reason2) is a broader imagination-dependent faculty that augments reason1 with the activity of probable reasoning. The dialectic between reason1 and reason2 leads to Hume skepticism, which is compounded by the fact that reason2 self-subverts if not constrained. Hume resolves these matters in the conclusion to Book 1 by conditionally committing to apply reason2 to matters of common life and social interest in a diffidently skeptical manner