336 TRANSACTIONS OF THE CANADIAN INSTITUTE. [Vox. VIII. 
or independence) to experience. But “‘experience’’ is next to ‘‘reality”’ the 
vaguest, the most illegitimate and deceptive conception and even Kant 
has confused the different meanings it can have. Reality and experience 
must be either defined in a perfectly arbitrary way or else they can be 
applied to everything, not even contradictories excluded. Therefore 
if we want to avoid these questionable though customary means of phil- 
osophical argument we may say as follows:—Extension i.e. the character- 
istic quality of space intuition is absolutely ultimate and unanalyzable. 
The order of our experience in space is produced under the co-operation 
of extension and magnitude. This order is complex and capable of 
differentiation and development. This capability for development does not 
predicate anything against the apodicticity of the known mathematical 
propositions. Thus the question answered in the negative by the represen- 
tatives of the Herbartian school, and answered in the affirmative by 
Lotze, Wundt, and Ebbinghaus, whether an eye absolutely at rest in a 
motionless surrounding could have space, must be decided in favour of the 
affirmative. Such an eye would have no occasion to perceive size and 
distance, but it would be capable of space distinction just as well as it 
would be of the distinction bright and dark, red and blue. It could per- 
ceive: this point is not that point, this direction is different from that 
one, this point or direction lies between those other points or directions. 
These are indeed the last fundamental facts from which the most recent 
treatments of the foundations of Geometry start.* 
The above question is usually only raised with regard to the “‘two 
dimensional”’ extension of thé spacial fields of the sense of sight and the 
sense of touch, for most philosophers and psychologists, even if they adhere 
with regard to the two dimensional fields of vision and touch to the 
nativistic hypothesis, think it necessary toadmit that the third dimension is 
only the empirical product of inference. Thus for instance Max 
Kaufmann} and recently Ebbinghaust have emphasized that the 
two dimensional or surface nature of visual space is something 
original and elementary. The latter thinks this original surface- 
perception is similar to that which we have when we look into a 
transparent liquid, into the darkness of an un l!uminated shaft, into a thick 
fog, towards the sky or into the glare of a big flame. But I do not see 
what essential distinction there can be between these impressions and other 
ordinary surfaces unless it is in the difference of intensity, of saturation 
or colour tone. The flame presents itself as a bright orange yellow, the fog 
* David Hilbert, Grundlagen der Geometrie, Festschrift zur Enthuellung des 
Gauss-Weber-Denkmals in G6ttingen 1899. 
+ Immanente Philosophie pp ro ff. (3) 
t Psychologie Vol. II. 440. 
