Abstract
Philosophers often write in a particular mood; their work is playful, strident, strenuous, or nostalgic. On the face of it, these moods contribute little to a philosophical argument and are merely incidental. However, I will argue that the cognitive science of moods and emotions offers us reasons to suspect that mood is relevant for philosophical texts. I use examples from Friedrich Nietzsche and Rudolph Carnap to illustrate the role moods play in their arguments. As readers and writers of philosophical texts, we do well to attend to mood.