448 INDUCTION. 



antecedent artificially, and if, when we do so, the effect 

 follows, the induction is complete ; that antecedent is 

 the cause of that consequent*. But we then have 

 added the evidence of experiment to that of simple 

 observation. Until we had done so, we had only 

 proved invariable antecedence, but not unconditional 

 antecedence, or causation. Until it had been shown 

 by the actual production of the antecedent under 

 known circumstances, and the occurrence thereupon 

 of the consequent, that the antecedent was really the 

 condition on which it depended ; the uniformity of 

 succession which was proved to exist between them 

 might, for aught we knew, be (like the succession of 

 day and night) no case of causation at all ; both 

 antecedent and consequent might be successive stages 

 of the effect of an ulterior cause. Observation, in 

 short, without experiment (and without any aid from 

 deduction) can ascertain uniformities, but cannot prove 

 causation. 



In order to see these remarks verified by the 

 actual state of the sciences, we have only to think 

 of the condition of natural history. In zoology, for 

 example, there is an immense number of uniformities 

 ascertained, some of coexistence, others of succession, 

 to many of which, notwithstanding considerable varia- 

 tions of the attendant circumstances, we know not 

 any exception : but the antecedents, for the most 

 part, are such as we cannot artificially produce ; or, 

 if we can, it is only by setting in motion the exact 



* Unless, indeed, the consequent was generated not by the 

 antecedent, but by the means we employed to produce the ante- 

 cedent. As, however, these means are under our power, there is so 

 far a probability that they are also sufficiently within our knowledge, 

 to enable us to judge whether that could be the case or not. 



