Ancient Jainism came up with a system of analyzing how we perceive something as real, as opposed to being our imagination. This scheme is called “sapta-bhaṅgi” (“seven branches” or points of perceiving reality).
The seven possibilities of analyzing reality are:
(1) Maybe something exists from one point of view
(2) Maybe it does not really exist, but we might think it does
(3) Maybe it both exists from one point of view and does not from another
(4) Maybe it exists but cannot be humanly expressed
(5) Maybe something exists only from one point of view but is still inexpressible
(6) Maybe something does not really exist, and cannot be expressed as such
(7) Maybe something does not exist, cannot exist, and is inexpressible too
Because of this kind of itemizing of possibilities, Jainism has been called “the doctrine of ‘maybe’.”