Spinoza's account of belief entails that if A has two ideas, p and q, with incompatible content, A believes that p if the idea of p is stronger than the idea of q. This seems to leave little space for dominant non-beliefs, or cases in which there is discord between one's beliefs and one's affective-behavioral responses. And yet Spinoza does allow for two classes of dominant non-beliefs: efficacious fictions [fictiones] and ideas that conduce to akrasia. I show how Spinoza can account for dominant non-beliefs within his model of cognition by distinguishing between the doxastic and the affective powers of ideas and by suggesting that doxastic power is best understood diachronically. While other scholars have stressed the elegance of Spinoza's account of ideas, this paper highlights the sophistication and flexibility of his account.