Philosophers of mind have extensively debated the intuition that experience provides unique knowledge. Responding to influential thought experiments by Thomas Nagel, Frank Jackson and others, philosophers have developed a series of replies to the question of ‘what experience teaches’. Aside from these theoretical considerations, the same intuition (i.e., that experience generates knowledge) forms the foundation of a rapidly increasing development in psychiatry, namely the practice of expertise-by-experience, which is premised on the intuition that former patients have unique and complementary knowledge based on their lived experience with mental illness. However, the practice of expertise-by-experience is hindered by the same theoretical problem that philosophers have addressed: it is very difficult to pin down what experience teaches, exactly, and hence how we might justify or legitimize the role of experts-by-experience for specific tasks and roles.