This dissertation critically explores how social learning helps to shape planning. It conceptualises social learning from a psychology-based perspective as the process through which individuals and small groups learn through interaction. A key insight is that individuals and small groups tend to learn how to maintain what they know, more than how to change it. Social learning does not easily lead to more sustainability or social justice. This way of perceiving social learning reveals how acknowledging its various facets - wherever they may lead - helps to value and understand the depth of the known, and to be more aware of the breadth of the unknown. Social learning is key to show planners - and the world at large - that both roots and wings are part of us, and they matter equally. Roots give historical awareness, depth and grounded insights; wings give imagination, breadth and change. Planning needs both.