The darśanas or Indian philosophical systems have bestowed considerable attention on the methods of obtaining know-ledge. Means of such knowledge vary from three to six. It is the Pūrva-mīmāṁsā system that accepts and describes six such means, which by the way, form the maximum of such series.
‘Arthāpatti’ or ‘postulation’ is the penultimate in this series. It is described as the necessary supposition of an un-perceived fact which alone can explain a phenomenon that demands an explanation. Suppose it is observed that a man is fasting during the day and yet is growing fat. It is impossible to reconcile these two facts—fatness and fasting—unless we admit that he eats at night! This postulation is ‘arthāpatti.’
The Mīmāṁsakas and Advaitins maintain that this is a distinctive source of knowledge whereas others include it under ‘anumāna’ or inference.
See also PRAMĀṆAS.