Like Nyaya, the later Buddhists gave utmost emphasis on the causal relation for making an inference.
Buddhists consider that if five conditions are seen between two phenomena, then they are accepted as causally related.
On the basis of such causal connection vyapti can be ascertained. Here there is the need of a universal statement which serves as vyapti for inference. There can be no valid inference without vyapti.
If the causal connection between the smoke and the fire is established through the method of Pancakarani (five causal conditions), then the cause can be inferred from the effect logically.
Thus Buddhist logicians follow five steps in the form of panca-karani in the following manner to establish the causal connection and vyapti.
i) When the cause is not present, the effect is also not present (In absence of fire, smoke does not appear)
ii) Cause is present (we abserve fire)
iii) The effect succeeds the cause immediately (smoke is perceived immediately)
iv) The cause disappears (the fire is extinguished)
v) The effect also disappears (the smoke disappears)
To ascertain vyapti the Buddhists rely on the law of causation. Their argument is very much like in the pattern of scientific intuition.
The conclusion is drawn by the help of a general premise which is obtained through the law of causation. The general premise serves the purpose of vyapti in this form of inference. Thus vyapti also plays a vital role in the Buddhistic form of inference.