PRESIDENTIAL ADDRESS. 357 



magnitude : thu neat, liini, tidy, exact world wliicli is tlie goal of sdentific 

 thought. 



My contention is that tins world is a world of ideas, and that its internal rela- 

 tions are relations between abstract concepts, and that the elucidation of the pre- 

 cise connection between this world and the feelings of actual experience is the 

 fundamental question of scientific philosophy. The question which I am inviting 

 you to consider is this : How does exact thought apply to the fragmentary, vague 

 continuu of experience 'i I am riot saying that it does not apply, quite the 

 contrary. But I want to know how it applies. The solution I am asking for 

 is not a phrase however brilliant, but a solid branch of science, constructed 

 with slow patience, showing in detail how the cxjrrcspondence is effected. 



The first great steps in the organisation of thought were due exclusively to 

 the practical source of scientific activity, without any admixture of theoretical 

 impulse. Their slow accomplishment was the cause and also the effect of the 

 gradual evolution of moderately rational beings. 1 mean the formation of the 

 concepts of definite material objects, of the determinate lapse of time, of simul- 

 taneity, of recurrence, of definite relative position, and of analogous funda- 

 mental ideas, according to which the flux of our experiences is mentally 

 arranged for handy reference : in fact, the whole apparatus of common-sense 

 thought. Consider in your mind some definite chair. The concept of that chair 

 ie simply the concept of all the interrelated experiences connected with that 

 chair — namely, of the experiences of the folk who made it, of the folk who sold 

 it, of the follv who have seen it or used it, of the man who is now experiencing 

 a comfortable sense of support, combined with our expectations of an analogous 

 future, terminated finally by a different set of experiences when the chair 

 collapses and becomes fire-wood. The formation of that type of concept was 

 a tremendous job, and zoologists and geologists tell us that it took many tens of 

 millions of years. I can well believe it. 



I now emphasise two points. In the first place, science is rooted in what I 

 have just called the whole apparatus of common-sense thought. That is tlie 

 datum from which it starts, and to which it must recur. We may speculate, if 

 it amuses us, of other beings in other planets who have arranged analogous 

 experiences according to an entirely different conceptual code — namely, who 

 have directed their chief attention to different relations between their various 

 experiences. But the task is too complex, too gigantic, to be revised in its 

 main outlines. You may polLsh up common sense, you may contradict it in 

 detail, you may surprise it. But ultimately your whole task is to satisfy it. 



lu the second place, neither common sense nor science can jiroceed with their 

 task of thought organisation without departing in some respect from the strict 

 consideration of what is actual in experience. Think again of the chair. 

 Among the experiences upon which its concept is based, I included our expecta- 

 tions of its future history. I should have gone further and included our 

 imagination of all the possible experiences which in ordinary language •we should 

 call perceptions of the chair which might have occurred. This is a difficult 

 question, and I do not see my way through it. But at present in the construc- 

 tion of a theory of space and of time, there seem insuperable difficulties if we 

 refuse to admit ideal experiences. 



This imaginative perception of experiences, which, if they occurred, would 

 be coherent with our actual experiences, seems fundamental in our lives. It is 

 neither wholly arbitrary, nor yet fully determuied. It is a vague background 

 which is only made in part definite by isolated activities of thought. Consider, 

 for example, our thoughts of the unseen flora of Brazil. 



Ideal experiences are closely connected with our unaginative reproduction of 

 the actual experiences of other people, and also with our almost inevitable 

 conception of ourselves as receiving our impressions from an external complex 

 reality beyond ourselves. It may be that an adequate analysis of every source 

 and every type of experience yields demonstrative proof of such a reality and of 

 its nature. Indeed, it is hardly to be doubted that this is the case. The 

 precise elucidation of this question is the problem of metaphysics. One of the 

 jjoints which I am urging in this address is that the basis of science does not 

 depend on the a.ssumption of any of the conclusions of metaphysics ; but that 



