Essays Towards a Theory of Knowledge | Page 6

and
utilises in his discursive employment of the idea of any physical thing
is what we have ventured to call its dynamic significance. And the very
careful analysis which M. Villey has made of the mental conceptions of
the blind clearly shows that in their case he has reached exactly the
same conclusion.
Our fundamental conceptions of the external world are therefore
derived from and are built up out of the data of our exertional Activity
combined with the interruptions which that Activity perpetually
encounters, and in which sensations arise. It would indeed be a useful
work of psychological analysis if the conditions of exertional action
were carefully and systematically investigated--much more useful than

most of the trifling experiments to which psychological laboratories are
usually devoted.
The principal elements of such a scheme would be--
(1) The force of gravity. This force constantly operating constrains the
organism to be in constant contact with the earth on which we live. But,
further, it gives us the definite idea of Direction. It is from the action of
gravity that we derive our distinction between Up and Down from
which as a starting-point we build up our conception of tridimensional
Space. And in this respect it must be remembered that as the areas of
spheres are proportional to the squares of their radii it necessarily
follows that gravity if it acts uniformly in tridimensional Space must
vary in intensity in proportion to the square of the distance of the point
of application from the centre of origin. Gravity and tridimensionality
are in short necessarily connected.
(2) The same law which determines the force of gravity seems to
determine also the force of cohesion, and therefore the form of material
bodies. These, therefore, are necessarily subject also to
tridimensionality, and in the force which generates solid form we find a
second source of our elementary spatial ideas.
Such form is the expression of an obstacle to action which determines
all our movements, and in which we discover those forms of the
limitations of activity which we call spatial characters.
(3) Organic Dualism is a third determinant of activity, and thus also a
source of spatial ideas.
The structural dualism of the human body, its right and left, its front
and back, etc., furnish our activity with a set of constant forms to which
its action must conform, and which necessarily also partake of, and
help us to conceive of tridimensional form. It is interesting to note that
this dualism characterises the organs specially adapted to serve
exertional action rather than those which serve our vegetal or nutrient
life.

The way in which our spatial conceptions are ever extended and built
up out of the data of action is also well illustrated in the case of the
blind, and to this also M. Villey devotes an interesting chapter under
the title La conquête des représentations spatiales.
This is effected in their case by the high development of what we must
call active touch. Just as we distinguish between hearing and listening,
between seeing and looking, so must we distinguish between touching
and palpation.
Mere passive touch gives a certain amount of information, but
comparatively little. It is necessary to explore; that is what is done in
active touch--palpation--of different degrees.
The sensitiveness of the skin varies at different places from the tongue
downwards. Palpation by the fingers marks a further stage. The blind
also, we are told, largely employ the feet in walking as a source of
locative data.
To the concepts reached by such palpation with the hand, M. Villey
gives the name of Manual Space. In this connection he thinks it
necessary to distinguish between synthetic touch and analytic
touch--the former resulting from the simultaneous application of
different parts of the hand on the surface of a body, the latter that which
we owe to the movements of our fingers when having only one point of
contact with the object the fingers follow its contour. Various examples
of the delicacy of the information thus obtainable are given. Following
two straight lines with the thumb and index respectively, a blind man
can acquire by practice a sensibility so complete as to enable him to
detect the slightest divergence from parallelism.
The analysis passes on from the data of Space manual to those of Space
brachial; then to the information derived from walking and other
movements of the lower limbs, and then to the co-ordination of the
information derived from the sensations of hearing, which is
necessarily very important to the blind.
The conclusion of the whole matter is that our principal spatial ideas

are common alike to the blind and the vident. Both can be taught and
are taught the same geometry. Both understand one another in the
description of spatial conditions. The common element cannot possibly