Anyathakhyati is a Nyaya theory of perceptual illusion. According to the Naiyayikas, anyathakhyati is a theory meant to explain the concept of illusion. They used the word viparyaya for illusion or erroneous knowledge. In illusion, an object is cognized to be something other than what it actually is. Perceiving a piece of oyster shell or nacre as a piece of silver or a rope as a snake, are the oft-quoted examples of illusion. The object of illusion is not an absolutely non-existent thing, sence such a thing can never be cognized. A rope is mistaken for a snake only by a person who has earlier seen a snake elsewhere. At the same time, it is not existent at the time or site of illusion. The object of illusion has a definite external location as in the case of any normal perceptual object. In illusion, we attribute a character to a perceived thing which does not belong to it. To explain how we ascribe this false character and how this false character appears as something actually perceived, the Naiyayikas proposed a theory known as Anyathakhyativada.
According to the theory of Anyathakhyati, first there is the
contact of the sense organ with the object. Because of certain factors like
insufficient light, the sense organ (which itself may have a defect) cognizes
the generic features of the object but fails to cognize its distinctive
features. Since these generic features are also associated with some other
thing, the given sensation is misinterpreted as something other than what it
is. In the example of cognizing a piece of nacre as piece of silver, there is
the first the contact of the eyes with the piece of nacre. Because of certain
defects, the eyes cognize such generic features as its luster and fail to
cognize such generic features as its luster and fail to cognize its distinctive
features. Since the cognized generic features (like luster) are also associated
with silver, perceived elsewhere at some other time, the memory-images
(samskara) of the distinctive features of silver are recollected. Through such
recollection, there takes place an extraordinary kind of contact
(jnana-lakshana-sannikarsha) between the sense-organ and the mental image of
silver, leading to the extraordinary perception of silver. Illusion takes place
when the silver so perceived is referred to as a piece of nacre that is present
before and perceived by the sense organ. Thus, a piece of nacre is mistaken for
silver. Illusion consists in associating silver with a piece of nacre wherein
the silver does not exist. Illusion is a single cognition wherein the
presentative and the representative cognitions are fused. There is no error at
the level of sensation. It is only when sensation is determined as something
other than what it is (anyatha) due to its association with the memory images,
that illusion takes place.
The term anyatha means ‘elsewhere’ or ‘otherwise’. The
presented object is perceived ‘otherwise’ and the represented object is ‘elsewhere’.
The object of illusion is real but yet, it is erroneous because the object perceived
is not in the place where it is perceived.