92 THE SCIENCE OF LOGIC 



ance with which a certain kind of object or event acts. Our problem is 

 better expressed as that of discovering laws of nature than causes&quot; J 



In explanation of the monsoons, for instance, we are expected &quot; to point 

 out the difference in the power of the sun at any place produced by the 

 varying directness of its rays ; how the sea gives off vapour ; how vapour 

 absorbs part of the heat of the sun s rays ; how the heated water circulates 

 with the colder ; how the earth absorbs and retains the heat of the sun ; how 

 air is expanded by heat ; how the principle of atmospheric pressure acts under 

 conditions of different expansion ; and so forth. Then we can see that if a cer 

 tain combination of events occurs, a particular complex result must arise ; if the 

 sun travels from over the surface of the sea to over the interior of a continent, 

 we shall find monsoons ; for the difference between summer and winter 

 temperature will in the interior be very great, but on the sea, owing to the 

 way in which the moisture of the air absorbs part of the heat, and the currents 

 in the water carry away part, it is not so great ; hence as summer is ending, 

 the air inland will be hotter and have expanded more than out at sea, as 

 winter is ending, it will be colder and have contracted more ; so that at one 

 time the current of air sets inland in accordance with the laws of atmospheric 

 pressure, and at another time it sets shoreward &quot;. a 



Here we have an admirable example of the explanation of a complex 

 effect by stating the laws according to which the various contributing 

 agents act in such conjunctions as to bring about this effect. It is not the 

 &quot; laws &quot; or their combinations that produce the effect ; it is the various 

 &quot; causes &quot; or &quot; agents &quot; that produce the effect, by acting each according to 

 its own uniform &quot; principle of action,&quot; that is, according to the &quot; law &quot; of its 

 nature (217). These &quot;laws&quot; are both descriptive and explanatory: de 

 scriptive of the modes of action of the causes, and explanatory of the effects by 

 showing how these latter are brought about by those causes (255). 



JOSEPH, Logic, chaps. xix.,xxii. WELTON, op. cit. ii., pp. 1-60. VENN, 

 Empirical Logic, chaps, i., ii., iii. MERCIER, Logique, pp. 298-332. MEL- 

 LONE, op. cit., pp. 264 sqq. JOYCE, Logic, chaps, xv., xviii. MILL, Logic, 



1 JOSEPH, op. cit., p. 444 (italics ours). *ibid., pp. 444-5. 



