CONCEPTS OF &quot;REASON&quot; AND &quot;CAUSE&quot; 85 



the one &quot;reciprocal&quot; or &quot;commensurate&quot; cause of that effect. 

 Hence the question arises, whether Science ought to aim at the 

 discovery of reciprocating causal relations, or merely of causal 

 relations such that although the &quot;cause&quot; will necessitate the 

 &quot; effect,&quot; this latter will not necessitate the former, but admit of 

 a &quot; Plurality of Causes &quot; (cf. 138). 



If we take a &quot; physical &quot;or &quot; necessary &quot; &quot; cause &quot; in the 

 popular sense of some prominent or striking event which, when 

 it happens, is always followed by another remarkable event (the 

 &quot;effect&quot;), it will be evident that though the same natural cause, 

 acting in similar circumstances (e.g. administering deadly poison), 

 always produces the same effect (e.g. death), nevertheless the same 

 effect (death) need not be always produced by the same cause 

 (poison) : that although &quot; effect &quot; can be inferred from &quot; cause &quot;- 

 &quot;posita causa, ponitur effectus&quot; still the converse, &quot; cause &quot; from 

 &quot; effect &quot; &quot;posito ejfectu, ponitur causa &quot; cannot be lawfully in 

 ferred. And the reasdn is that in this sense of the term &quot; cause,&quot; 

 the same &quot; effect &quot; may be produced by different &quot; causes &quot; : that one 

 and the same effect death, for example may be due to any 

 one or more of an indefinite multitude of &quot; causes &quot;. We speak 

 popularly of an agency as the &quot;natural cause&quot; of a given result 

 or effect, provided that this agency be sufficient (or necessitating] 

 even though it be not indispensable, in the sense of being the only 

 possible agency for the production of such an effect. And formal 

 logic, recognizing this mode of thought and expression, and ap 

 plying the Law of Parsimony (94), prohibits the simple conver 

 sion of the conditional proposition, which connects cause with 

 effect as logical antecedent with consequent, as reciprocal (140). 

 If, therefore, we take the terms &quot;physical cause&quot; and &quot;effect&quot; in 

 this practical meaning, the former as that which always and 

 necessarily produces the latter, and the latter as that which is 

 produced, no doubt, by the former, but which is or may be produced 

 otherwise as well, then it will be true to say that one and the 

 same &quot; effect &quot; may have a plurality of &quot; causes,&quot; though one and 

 the same (natural or necessary) &quot; cause &quot; cannot have a plurality 

 of &quot; effects &quot;- 1 



1 Evidently, the co-operation or &quot; composition &quot; of many partial causes may 

 contribute to the production of one single effect : e.g. a person s death may be due 

 to a complication of diseases no single one of which would separately have proved 

 fatal (cf. 244). But &quot; composition &quot; of (partial) causes is quite a different thing from 

 &quot;plurality of causes&quot;. The latter means that one and the same effect (death) 

 may, in different instances, be produced by entirely different total causes (poison, 

 shooting, smallpox, old age, etc.). 



