In Hinduism, non-valid knowledge is known as Aprama. It is knowledge the content of which is susceptible to sublation or invalidation; hence invalid or untrue knowledge. Knowledge is classified into two by Naiyayikas, viz., memory and experience. The latter again is divided into two – valid knowledge and invalid knowledge. All knowledge which is not received through pramanas (means of valid knowledge) is aprama (a – not; prama – valid knowledge). This aprama too appears through a means of knowledge itself either wrongly applied or partially. Aprama is defined as knowledge of a particular objects as characterized by a feature which it does not really have. The following are grouped as invalid knowledge – samsaya (doubt); mithya or bhrama (error); and tarka (erroneous argument).
When an object is seen to possess two or more contradictory
features which cannot coexist, its knowledge is said to be doubtful since it
cannot lead to any definite conclusion. A stock example is one’s inability to
decide whether the tall stem standing at a distance is just a stem or a man.
Mistaking something for something else is error, e.g. the mother-of-pearl being
mistaken for silver on account of its partial visibility of the shining side.
Since the worldviews of many Hindu philosophers have been shaped on their theory
of error, this theory has been discussed elaborately as khyativada or ‘theory
of error.’ They variously claim that the object (silver) seen is nothing but
atmakhyati (the projection of mind), astkhyati (non-existence), a khyati
(non-differentiations of two different but valid pieces of knowledge),
anayathakhyati (appearance of an object existing elsewhere through some extraordinary
perception) subscribed to by Buddhists (first two views), Prabhakara Mimamsakas,
Naiyayikas and Advaitins respectively.
Memory is classified neither as true nor as false, for tis
veracity depends on the validity of the experience and strength of the
impressions.