X^- THE GRAMMAR OF SCIENCE. 301 



sense-impression. Since, therefore, the percept contains elements 

 not given in the immediate sense-impression, but contributed from 

 the stored sense-impresses of the percipient mind, we may say that 

 it is, in part at least, and often to a large extent, constructed by the 

 percipient in the moment of perception. The polished Ammonite 

 which I use as a letter-weight is a percept suggested by certain 

 retinal sense-impressions. As an object, it is resisting to the touch, 

 heavy, and so forth. I can readily verify the reality of the object 

 in these respects through the appropriate channels of tactual and 

 muscular sense-impression. It is, moreover, a reality not only for 

 me, but for any normal human being who may chance to be by my 

 side. As a " construct " it is not only individual, but social : a per- 

 ceptual product not only of me, but of man. Such, in brief, are the 

 conclusions which result from the psychological analysis of the 

 process of perception, and which are accepted and endorsed by Mr. 

 Pearson. Here psychology as a science is content to leave the 

 matter. But if we go further and enquire whether there is an 

 external " reality " which is the occasion of my percept and that of 

 my neighbour, we enter upon a metaphysical problem. We must 

 note that the word " reality " is here used in a sense different from 

 that in which I used the word real above. There I meant by real 

 common to me, you, and all normally constituted human beings. Here 

 by "reality" is meant an existence independent of human perception. 

 Let us hear what Mr. Pearson says with regard to this " reality." 

 " Turn the problem round, and ponder over it as we may," he says, 

 " beyond the sense-impressions . . . we cannot get. Of what is 

 beyond them, of ' things-in-themselves "... we can know but 

 one characteristic, and this we can only describe as a capacity for 

 producing sense-impressions . . . This is the sole scientific 

 statement which can be made with regard to what lies beyond sense- 

 impression." Even this he qualifies, if he does not nullify, a little 

 later, when he says: "There is no necessity, not even logic, in the 

 statement that behind sense-impressions there are ' things-in-them- 

 selves ' /roii^awo' sense-impressions." If I understand him rightly, 

 Mr. Pearson's view is that the very utmost we can predicate con- 

 cerning the occasion of sense-impressions is its existence ; of its " real " 

 nature we can assert nothing, not even its externality to the percipient. 

 Presumably, however, he would not deny that there is something 

 about it which we symbolise as externality or outness from ourselves as 

 percipients. 



Before leaving this question of perception, or the " construction " 

 of external objects, there is one further remark I have to offer. We 

 may agree with the result of the analysis, and yet we may hold that 

 its constant obtrusion in the consideration of the phenomena of what 

 for perception is the external world, is likely to lead rather to the 

 confusion of than to the simplification of our scientific treatment. These 

 conceptual results of the analysis of the perceptual process are on a 



