The Domain of Physical Science 195 



fairly entertain some doubt as to these assertions which he is unable 

 to check, it may not be without interest to him to learn something 

 of the general direction in which scientific thought appears to be 

 tending (rightly or wrongly) now that it is confronted with a 

 conception of the material world widely different from that which 

 was the basis of disputes between science and religion in the last 

 century. 



Notwithstanding its professed principle of treating all points of 

 view impartially, physics does in practice give a preference to the 

 the view of the microbe over that of the man. If you ask a scientist 

 what is the ultimate truth about the nature of the world so far as 

 he knows it, he will begin to describe it as it appears under his most 

 powerful magnifying glass : he will tell you about the trees, not 

 about the forest — ^about electrons, not planks. It would be 

 incorrect to say that he ignores the large-scale truths. Whole 

 branches of his work are devoted to ascertaining how the little 

 things conspire to give the great things, how new properties arise 

 in a crowd which are not properties of the individuals of that 

 crowd. Care is taken to provide " macroscopic " equations for 

 the human scale of appreciation of phenomena as well as " micro- 

 scopic " equations for the microbe. But there is a difference in 

 the attitude of the physicist towards these results ; for him the 

 macroscopic equations — the large-scale results — are just useful 

 tools for scientific and practical progress ; the microscopic view 

 contains the real truth as to what is actually occurring. The 

 reason for this preference is that our theoretical reasoning is of such 

 a kind as to pass much more readily from small-scale to large-scale 

 results than vice versa. It is, therefore, usually considered that the 

 large-scale truths are implied by the small-scale truths, and are 

 therefore not required to be mentioned separately in stating our 

 conception of the external world. All the properties of impene- 

 trability, extension, elasticity, colour, etc., of the plank are (in 

 their physical aspects) supposed to be deducible from the small- 

 scale specification of it as a swarm of electric charges ; so that a 

 sufficiently educated intelligence ought to discern in the conception 

 of the plank as a swarm of particles all that goes to make up the 

 appearance of the plank to the human point of view. On the 

 other hand, it is not considered that the electronic constitution of 

 the plank is implied in a descr>ption of its large-scale appearance. 

 There are already signs that this undue insistence on microscopic 



