A broad range of findings across the cognitive sciences has emerged revealing surprising flexibility and dynamic flux in a large range of cognitive domains. These include exciting new discoveries of neuroplasticity well into adulthood, discoveries of great cognitive variability as a function of the statistical properties of ones environment (from patterns in natural languages, to those in embodied experience), and discoveries of the surprisingly dynamic microstructure of cognition. Do such findings demonstrate that many fundamental aspects of cognition are indeed quite flexible? Or does finding that some aspect of cognition is flexible mean that it is therefore not fundamental? Or is flux the only truly fundamental thing about cognition in the first place? The talks in this symposium will speak to these questions from a variety of perspectives (incorporating ideas from development, neuroscience, computational insights, and cross-cultural approaches), and help us clarify our thinking about what such findings mean.