What is the difference between sadhyavikalata and sadhanavikalata dosha ?
Before answering this, let us understand that these doshas are often used to point out to the logical fallacy. There are others like bhagasiddhi, vyabhichara etc. too.
To understand these doshas, we have to understand the avavaya – limbs, of the tarka – syllogory. Generally, the logicians accept five limbs in a tarka, we vedantins accept only three, either the first three or the last three of the five limbs.
Pratigna, hetu, udharana are the important limbs.
Pratigna is the aim, where the sadhya – the one we want to prove in the paksha – the place where it needs to be proved is specified. Ex. Parvato vahnimaan, the mountain has fire. Here the mountain is the
Hetu is the reasoning we give to prove the aim. Ex. Dhumaat / dhmavatvaat, since it has smoke. Smoke is the pointer which always co-exists when there is fire.
Udharana is the example to prove the reasoning is correct with respect to the aim. Ex. Mahanasavat, like the kitchen. The concomitance ‘where there is smoke there is fire is gained’ from different places, like, kitchen, sacricial fire etc.
In sadhya and sadhanavikalata doshas, vikalata means handicapped or absence (abhava).
If the hetu does not fit in with the sadhya then it is sadhyavikalata dosha.
If the hetu does not fit in with the udhaharana it is sadhanavikalata dosha.
If the hetu fits only in a portion of the sadhya, it is bhagasiddhi. Bhaga – portion, assiddhi – is not proven. In a portion of the sadhya the reason does not fit.
If the hetu misses the sadhya completely, it is called vyabhicara dosha.