EMPIRICAL LAWS. 



541 



other words, an empirical law, that 

 we do not know whether it results 

 from the different effects of one cause 

 or from effects of different causes. 

 We cannot tell whether it depends 

 wholly on laws, or partly on laws and 

 partly on a collocation. If it depends 

 on a collocation, it will be true in all 

 the cases in which that particular 

 collocation exists. But since we are 

 entirely ignorant, in case of its de- 

 pending on a collocation, what the 

 collocation is, we are not safe in 

 extending the law beyond the limits 

 of time and place in which we have 

 actual experience of its truth. Since 

 within those limits the law has always 

 been found true, we have evidence 

 that the collocations, whatever they 

 are, on which it depends, do really 

 exist within those limits. But, know- 

 ing of no rule or principle to which 

 the collocations themselves conform, 

 we cannot conclude that because a 

 collocation is proved to exist within 

 certain limits of place or time, it will 

 exist beyond those limits. Empirical 

 laws, therefore, can only be received 

 as true within the limits of time and 

 place in which they have been found 

 true by observation ; and not merely 

 the limits of time and place, but of 

 time, place, and circumstance ; for 

 since it is the very meaning of an 

 empirical law that we do not know 

 the ultimate laws of causation on 

 which it is dependent, we cannot 

 foresee, without actual trial, in what 

 manner or to what extent the intro- 

 duction of any new circumstance may 

 affect it. 



§ 5. But how are we to know that 

 an uniformity ascertained by experi- 

 ence is only an empirical law ? Since, 

 by the supposition, we have not been 

 able to resolve it into any other laws, 

 how do we know that it is not an 

 ultimate law of causation ? 



I answer, that no generalisation 

 amounts to more than an empirical 

 law when the only proof on which it 

 rests is that of the Method of Agree- 

 ment. For it has been seen that by 



that method alone we never can ar- 

 rive at causes. The utmost that the 

 Method of Agreement can do is, to 

 ascertain the whole of the circum- 

 stances common to all cases in which 

 a phenomenon is produced ; and this 

 aggregate includes not only the cause 

 of the phenomenon, but all pheno- 

 mena with which it is connected by 

 any derivative uniformity, whether as 

 being collateral effects of the same 

 cause, or effects of any other cause 

 which, in all the instances we have 

 been able to observe, co-existed with 

 it. The method affords no means of 

 determining which of these uniformi- 

 ties are laws of causation, and which 

 are merely derivative laws, resulting 

 from those laws of causation and 

 from the collocation of the causes. 

 None of them, therefore, can be re- 

 ceived in any other character than 

 that of derivative laws, the derivation 

 of which has not been traced ; in 

 other words, empirical laws : in which 

 light, all results obtained by the 

 Method of Agreement (and therefore 

 almost all truths obtained by simple 

 observation without experiment) must 

 be considered, until either confirmed 

 by the Method of Difference or ex- 

 plained deductively, in other words, 

 accounted for a priori. 



These empirical laws may be of 

 greater or less authority according as 

 there is reason to presume that they 

 are resolvable into laws only, or into 

 laws and collocations together. The 

 sequences which we observe in the 

 production and subsequent life of an 

 animal or a vegetable, resting on the 

 Method of Agreement only, are mere 

 empirical laws ; but though the ante- 

 cedents in those sequences may not 

 be the causes of the consequents, both 

 the one and the other are doubtless, 

 in the main, successive stages of a 

 progressive effect originating in a 

 common cause, and therefore inde- 

 pendent of collocations. The uni- 

 formities, on the other hand, in the 

 order of superposition of strata on the 

 earth, are empirical laws of a much 

 weaker kind, since they not only are 



