As I concluded the previous post, I argued that the Deleuzian extension of Hume’s project entailed both the affirmation of monism (Spinoza) and multiplicity (Hume). This point is made crystal clear in A Thousand Plateaus when Deleuze and Guattari announce that “pluralism = monism” (ATP, p. 2; see this earlier post where I discuss this theme in the context of William James’ radical empiricism). This effort to bring Hume and Spinoza together, however, is fraught with difficulty, or at least apparently so, in a philosophical landscape that has been forever altered by Kant’s project. Since Kant was woken from his dogmatic slumber, Hume and Spinoza have come to be rethought, if rethought at all, in the context of the conditions for the possibility of experience. In the case of Hume, this has largely led his philosophy to be read as a project in epistemology. Hume comes to be seen as a precursor of a Bayesian epistemology whereby knowledge comes to be constituted through a process of induction that constitutes degrees of belief. Spinoza, at worst, is thrown into the refuse pile of philosophical dogmatists, one of the philosophers who accepted, without question, that guarantees of our knowledge. Spinoza, in fact, goes much further than either Descartes and Leibniz in that while they accept God as the unquestioned guarantor of our knowledge of the world (Descartes) as well as the harmony of the world itself (Leibniz), God remains inaccessible and unknowable; Spinoza, by contrast, argues in the last half of Part 5 of the Ethics that even God can be known.
To state the contrast between Spinoza the dogmatist and Hume the skeptic, one could say that Spinoza presupposes the identity that grounds knowledge while Hume argues that this identity comes to be constituted. Husserl remarked upon this aspect of Hume’s thought, and it is for this reason that I have argued for a Humean phenomenology (see this). So how then can one bring Hume and Spinoza together? Put simply, through a rethinking of the principle of sufficient reason (PSR). And this brings me back to the issue that in part spawned the New Hume debate – to wit, Hume’s claim that the “particular powers, by which all natural operations are performed” are powers that provide the reason for the regularities of nature but these powers “never appear to the senses.” What are these powers? The simple answer to this question is that these are the laws of nature that are the subject of natural science, and it is precisely the nature of these powers that are revealed, over time, through the process of scientific enquiry. We could say that this is a scientific explanation of facts. That which appears to the senses, therefore, would bring in our mental faculties and the epistemological problems of how we come to know the “particular powers” of nature. With this we have an epistemological explanation, and form here we are not too far from the Bayesian epistemology mentioned above.