My dissertation investigates whether Spinoza can consistently uphold his doctrine of parallelism while acknowledging the existence of four distinct kinds of ideas that appear to challenge it. Parallelism, for Spinoza, asserts a one-to-one correspondence between each idea and its object, establishing an isomorphic structure between the mental and physical worlds. In my reading, this doctrine carries four implications: the number of modes under each attribute must be equal; every idea must correspond to and be true of its object; every idea must represent an external object; and each idea and its object are one and the same thing, although conceived under different attributes.

However, Spinoza also recognizes four kinds of ideas that seem to undermine these commitments: ideas of ideas, which appear to multiply the number of modes under the attribute of thought; false ideas, which seem to violate the requirement that every idea be true of its object; beings of reason, which have no corresponding object outside the mind; and the idea of God, which raises questions about how a mode can be identical to substance.

This project offers a systematic analysis of each of these apparent counterexamples. Drawing on Spinoza’s theory of distinctions and his account of representation, I argue that these ideas can be integrated into the framework of parallelism without sacrificing its core commitments. In doing so, the dissertation advances a more comprehensive understanding of Spinoza’s parallelism and sheds light on the character of Spinoza’s metaphysical system as shaped by the demands of parallelism.

Abstract: In the context of Spinoza’s monism, scholars have long struggled to explain why Spinoza considers the distinction between different attributes of God—the one and only substance—as a real distinction (E1p10s). In this paper, I argue that the difficulty arises from a general misunderstanding of Spinoza’s concept of real distinction. Despite their apparent similarity, Spinoza’s understanding of real distinction differs significantly from that of his predecessors, particularly Descartes. The difference is most evident in Spinoza’s interpretation of the criterion for real distinction, which he inherited from Descartes: “Two things are really distinct if one can be clearly conceived without the other, and vice versa.” Descartes understands this criterion to mean that two things are really distinct from each other if, even though the concept of one does not involve the concept of the other positively, it does involve the concept of the other negatively. On the other hand, Spinoza interprets the criterion as stating that one thing is really distinct from another if the concept of one does not include the concept of the other, whether positively or negatively. This seemingly subtle shift has significant implications at multiple levels. First, it breaks the traditional connection between real distinction and separability, resolving the apparent tension between Spinoza’s substance monism and the real distinction of attributes. Second, it also offers a coherent interpretation of Spinoza’s mode-identity thesis, showing how the mind and body, as modes conceived under different attributes, can be one and the same thing. Third, it demonstrates the compatibility of real distinction with numerical identity, directly challenging Leibniz’s Law, particularly the Indiscernibility of Identicals. Finally, it challenges the conventional understanding of distinction through negation and opposition, proposing instead that some distinctions are purely affirmative, opening up new ways of thinking about the nature of distinctions.

This paper is committed to a forthcoming volume on Spinoza’s theory of attributes, edited by Antonio Salgado Borge and Karolina Hübner. A draft is available upon request.

Abstract: This paper addresses the tension in Spinoza’s philosophy between his doctrine of parallelism and the occurrence of errors in human cognition. While Spinoza posits that all ideas agree with their objects, implying truth, he also acknowledges human cognitive limitations and errors. The standard solution suggests separating parallelism from the criterion for true ideas, allowing for misrepresentation. Challenging this solution, I argue for the inseparability of Spinoza’s doctrine of parallelism from his criterion for true ideas. However, this does not imply the impossibility of error. Contrary to what commentators commonly assume, I argue that, for Spinoza, error consists not in misrepresentation but in the limited nature of individual finite minds, particularly the restricted scope of the objects they can represent. This limitation leads to the finite mind’s perpetual occupation of a partial perspective regarding the world.

Draft is available upon request.

Abstract: This paper examines Spinoza’s puzzling treatment of beings of reason—objects of thought that correspond to nothing outside the intellect. Though Spinoza consistently uses this scholastic notion from the Short Treatise to the Ethics, his account raises three major interpretive challenges. First, unlike predecessors such as Suárez, Spinoza restricts the category to exclude self-contradictory and fictitious beings, prompting the Puzzle of Restricted Scope. Second, he classifies universals like genus and species as beings of reason, while also affirming the mind-independent existence of common properties, raising the Puzzle of Double Universality. Most fundamentally, the Puzzle of Missing Parallels questions how beings of reason can exist at all in a metaphysical system that requires each idea to correspond to something that exists formally in nature. I argue that all three puzzles can be resolved by understanding beings of reason as ideas of ideas. This interpretation accounts for their internal structure, distinguishes them from fictitious and self-contradictory beings, and preserves their compatibility with Spinoza’s doctrine of parallelism. It also clarifies how Spinoza can maintain both the anti-realist status of universals and the reality of common properties, thus offering a unified solution to a longstanding tension in his metaphysical system.

Draft is available upon request.