Now the
danger we are in when we adopt the sense datum notation is to
forget the difference between the grammar of a statement about
sense data and the grammar of an outwardly
similar statement about physical objects. (From this
point one might go on talking about the misunderstandings which
find their expression in such sentences as:
“We can never see an accurate circle”,
“All our sense data are vague”.
Also, this leads to the comparison of the grammar of
“position”, “motion”, and
“size” in
Euclidian
and in visual space. There
119.
is,
e.g., absolute position, absolute motion and
size in visual space.)