Many philosophers are very sanguine about the cognitive contributions of fiction to science and philosophy. I focus on a case study: Ichikawa and Jarvis’s account of thought experiments in terms of everyday fictional stories. As far as the contribution of fiction is not sui generis, processing fiction often will be parasitic on cognitive capacities which may replace it; as far as it is sui generis, nothing guarantees that fiction is sufficiently well-behaved to abide by the constraints of scientific and philosophical discourse, not even by the minimum requirements of conceptual and logical coherence