It may not be out of place here to mention that in later Nyaya works great emphasis is laid on the necessity of getting ourselves assured that there was no such upadhi (condition) associated with the hetu on account of which the concomitance happened, but that the hetu was unconditionally associated with the sadhya in a relation of inseparable concomitance. Thus all fire does not produce smoke; fire must be associated with green wood in order to produce smoke. Green wood is thus the necessary condition (upadhi) without which, no smoke could be produced. It is on account of this condition that fire is associated with smoke; and so we cannot say that there is smoke because there is fire. But in the concomitance of smoke with fire there is no condition, and so in every case of smoke there is fire. In order to be assured of the validity of vyapti, it is necessary that we must be assured that there should be nothing associated with the hetu which conditioned the concomitance, and this must be settled by wide experience (bhuyodarshana). Read more »
inference, kanada, linga, necessary condition, opposition, smoke fire, validity, valid reason