As per Hinduism, Mithya is a construct of the mind, which is inexplicable. According to Advaita, Brahman is the only reality. Everything else is non-real and is superimposed on it. The concept of adyasa (superimposition), which is in general linked with the concept of non-real is defined by Shankara in his commentary on Brahma Sutras as appearance elsewhere with a nature like recollection of what was seen before and cognition of something that does not exist.
The common example given for Mithya in Hindu religion are that of a rope in the dark perceived as a snake and a piece of shiny sea shell mistaken for silver. The nature of such an illusion is inexplicable (anirvacaniya) and is in reality identifiable with the underlying substratum.
To hold that the world is illusory or false does not mean that it is absolutely unreal. The Advaitins contend that the third category of in-determinability is either real or unreal. The world is not real just because it has a physical reality nor it is non-real because it is beyond physical reality.
The concept of non-real reality is discussed elaborately in many Advaitic texts like Nyaya rama dipavali, Tattva pradipika, Tarka sangraha of Anandagiri, Advaita-siddhi of Madhusudana Saraswati, Pramanamala and other texts of Anandabodha.
The Advaita-siddhi, Madhusudana Saraswati gives twenty six inferential arguments regarding mithya.
The general five definitions of Mithya are:
- Not being the locus of either reality or unreality (this definition is attributed to Padmapada)
- What is eternally negated in the same locus where it is cognized (mithya is an entity which appears in a place.
- What is contradicted by knowledge (illusory cognition is sublated where knowledge of underlying substratum arises)
- The locus of which is equally the locus of its eternal negation (attributed to Citsukha). To put it differently, an object which is invariable absent where it seems to be present is called mithya
- That which is other than reality (attributed to Anandabodha).
Source:
The Advaita Concept of Falsity (1967) Nirod Baran Chakraborty – Sanskrit College Kolkata
Encyclopedia of Hinduism Volume VII page 172 - IHRF