<p>This paper offers a new interpretation of Hume’s <i>Treatise</i> as a work written by a methodological solipsist. It argues that Hume anticipates later developments by launching a Fodorian project that is to be realised by Carnapian means. Hume develops an explanatory theory of mental operations based on an analysis conducted by way of similarity recollections in the stream of experience. The paper first presents the case for Hume’s commitment to methodological solipsism and then offers a reconstruction of the methodology with which his project is to be executed. Hume proceeds by analysing perceptions and the connections between them to account for their “nature” and the “principles” underlying their interaction. His analyses reveal the solipsistic methodological credo that Hume did not make explicit.</p>