Spinoza on Fictitious Ideas and Possible Entities

The aim of this article is twofold: to provide a valid account of Spinoza's theory of fictitious ideas, and to demonstrate its coherency with the overall modal metaphysics underpinning his philosophical system. According to Leibniz, in fact, the existence of romances and novels would be sufficient to demonstrate, against Spinoza's necessitarianism, that possible entities exist and are intelligible, and that many other worlds different from ours could have existed in its place. I argue that Spinoza does not actually need to resort to the notion of possible entities in order to explain the incontrovertible existence of fictions and fictitious ideas. In order to demonstrate this, I will first show how, according to Spinoza, true ideas of nonexistent things need not be regarded as fictitious ideas. Then I will show by which means Spinoza can justify the real existence of fictions and fictitious ideas in the human mind through our present knowledge of actually existing things, to conclude that fictitious ideas neither add anything to what we already know of things, nor do they increase the extent of the existing conceivable reality by demanding the existence of possible non-actualised entities.