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 (_bhuyodars'ana_).

Pras'astapada in defining inference as the "knowledge of that
(e.g. fire) associated with the reason (e.g. smoke) by the sight of
the reason" described a valid reason (_li@nga_) as that which is connected
with the object of inference (_anumeya_) and which exists
wherever the object of inference exists and is absent in all cases

349

where it does not exist. This is indeed the same as the Nyaya
qualifications of _pak@sasattva, sapak@sasattva and _vipak@sasattva_ of
a valid reason (hetu). Pras'astapada further quotes a verse to say
that this is the same as what Kas'yapa (believed to be the family
name of Ka@nada) said. Ka@nada says that we can infer a cause
from the effect, the effect from the cause, or we can infer one
thing by another when they are mutually connected, or in opposition
or in a relation of inherence (IX. ii. 1 and III. i. 9). We
can infer by a reason because it is duly associated
(_prasiddhipurvakatva_) with the object of inference. What this
association was according to Ka@nada can also be understood for
he tells us (III. i. 15) that where there is no proper association,
the reason (hetu) is either non-existent in the object to be inferred
or it has no concomitance with it (_aprasiddha_) or it has a doubtful
existence _sandigdha_). Thus if I say this ass is a horse because it has
horns it is fallacious, for neither the horse nor the ass has horns.
Again if I say it is a cow because it has horns, it is fallacious, for
there is no concomitance between horns and a cow, and though
a cow may have a horn, all that have horns are not cows. The
first fallacy is a combination of pak@sasattva and sapak@sasattva,
for not only the present pak@sa (the ass) had no horns, but no
horses had any horns, and the second is a case of vipak@sasattva,
for thos