y case of the existence of smoke should
be a case of the existence of fire, but every case of absence of fire
should be a case of absence of smoke. The former is technically
called _anvayavyapti_ and the latter _vyatirekavyapti._ But even this
is not enough. Thus there may have been an ass sitting, in a
hundred cases where I had seen smoke, and there might have
been a hundred cases where there was neither ass nor smoke, but
it cannot be asserted from it that there is any relation of concomitance,

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[Footnote 1: See _Antarvyaptisamarthana,_ by Ratnakaras'anti in the _Six
Buddhist Nyaya Tracts, Bibliotheca Indica_, 1910.]

347

or of cause and effect between the ass and the smoke. It
may be that one might never have observed smoke without an
antecedent ass, or an ass without the smoke following it, but even
that is not enough. If it were such that we had so experienced in
a very large number of cases that the introduction of the ass
produced the smoke, and that even when all the antecedents remained
the same, the disappearance of the ass was immediately
followed by the disappearance of smoke (_yasmin sati bhavanam
yato vina na bhavanam iti bhuyodars'ana@m, Nyayamanjari,_
p. 122), then only could we say that there was any relation of
concomitance (_vyapti_} between the ass and the smoke [Footnote ref 1]. But
of course it might be that what we concluded to be the hetu by the
above observations of anvaya-vyatireka might not be a real hetu,
and there might be some other condition (_upadhi_) associated
with the hetu which was the real hetu. Thus we know that fire
in green wood (_ardrendhana_) produced smoke, but one might
doubt that it was not the fire in the green wood that produced
smoke, but there was some hidden demon who did it.
But there would be no end of such doubts, and if we indulged
in them, all our work endeavour and practical activities would
have to be dispensed with (_vyaghata_). Thus such doubts as
lead us to the suspension of all work should not disturb or
unsettle the notion of vyapti or concomitance at which we
had arrived by careful observation and consideration [Footnote ref 2]. The
Buddhists and the naiyayikas generally agreed as to the method
of forming the notion of concomitance or vyapti (_vyaptigraha_),
but the former tried to assert that the validity of such a concomitance
always depended on a relation of cause and effect
or o