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INDIAN PHILOSOPHY
a limited number of negative instances too cannot assure us that there will be no instance in future of the presence of the former in the absence of the latter. But, he says, when it is known that A is either the cause or the nature of B then, since it is inconceivable that a thing can ever come into existence without its cause or can ever exist without its nature, we know the necesasary connection of B with A.27 Here Dharmakīrti assumes two things : (i) Every thing has a cause. (ii) The same cause always uniformly produces the same effect. We may grant that there is a general or broad regularity in the universe, that is, no thing is causeless (or natureless). But even then how are we to know that the cause which we have discovered in a particular instance will necessarily be the cause of similar things also in future ? To be more clear, we may admit that every event has a cause. Every event may have a cause, but the same cause need not always produce the same effect, nor the cause of the same effect be always the same. The human will, for example, is a cause but it does not always act in the same way under the same circumstances; to-day in a given situation I may act meanly; but it is possible that in a situation of the same kind I may act better to-morrow. To take another instance, it is not logically necessary that heat should cause bodies to expand rather than contract. We may accept that every event has a cause, but whether causes act uniformly, whether the same cause in the same situation always has the same effect can never be determined with certainty. Similarly, we can never assert with certainty that the specific gravity of mercury will always be 13.6 a number which is found to constitute the nature of mercury in observed cases. .
To this Dharmakirti's reply is as follows. Whatever is a cause of a particular type of thing remains for ever the cause of that type of thing. To think otherwise, namely, that one type of cause does not always produce only one type of effect is to go against logic. Y cannot be treated as an effect of X even in a single case if all Y is not an effect of some X. It is so because we call X the cause of Y, only if X invariably produces Y. Moreover, to say that at times Y is produced by X and at times it is produced by something other than X, that is non-X, would mean that Y possesses two contradictory natures. Again, this would suggest that the nature of a thing does not depend on its cause; and to grant this suggestion would mean that the thing comes into existence without any cause. This, in turn, would make it eternal and consequently devoid of efficiency which is the criterion of reality.
