Sunyata
The Buddhist doctrine, developed most rigorously by Nagarjuna, that all phenomena are empty of intrinsic nature — they exist only in dependence on conditions.
Sunyata, Sanskrit for emptiness, is one of the most important concepts of Mahayana Buddhist philosophy. The doctrine holds that all phenomena — physical, mental, and conceptual — are empty of intrinsic nature (svabhava): nothing exists independently or by its own being. Everything arises in dependence on causes and conditions, and the apparent self-existence of things is a cognitive distortion.
The most rigorous development of sunyata is Nagarjuna's Madhyamaka philosophy in the second century. Nagarjuna's Mulamadhyamakakarika argues for emptiness through a series of negative dialectical analyses: every category by which we attempt to characterize the ultimate nature of things — including emptiness itself — turns out under examination to lack the self-sufficiency it appears to claim. The doctrine has been developed differently in subsequent Madhyamaka, Yogacara, Hwaeom, and Zen traditions, but the central insight — that nothing exists from its own side — remains the philosophical core of Mahayana Buddhism.