1. The System of Necessity Given the synthetic character of Reid’s thought, it is natural to ask how best to enter into it. A promising avenue involves noting a pattern present in Reid’s work. In his work in epistemology and philosophy of mind, found primarily in An Inquiry into the Human Mind (I) and Essays on the Intellectual Powers of Man (EIP), Reid frames his project as a response to a general position that he calls the “Way of Ideas.” This position, which Reid says unites philosophers as diverse as Aristotle, Locke, Berkeley, and Hume, holds that we are never acquainted with the external world but only with “images” or sense data in the mind. What Reid says positively about our perception of the external world is couched as a response to this view (which he acknowledges he once accepted). Reid’s primary work in ethics, Essays on the Active Powers of Man (EAP), is also framed as a response to a general position, which he claims is adopted by philosophers as diverse as Spinoza, Leibniz, and Hume.…