The World as Percept 69perception. Then I soon notice that there is no trace of
similarity between the process occurring in the eye and
what I perceive as color. I cannot deny my color percept
by pointing to the process in the eye that takes place dur-
ing this perception. Nor can I find the color in the nerve-
and brain-processes; I only connect new percepts within
my organism to the first percept, which the naive person
places outside the organism. I only pass from one percept
to the next.
Moreover, there is a gap in the whole train of argument.
I am in a position to follow the processes within my or-
ganism, up to the processes in my brain, even though my
assumptions become ever more hypothetical the closer I
come to its central processes. The path ofexternalobser-
vation ends with the process in my brain; more precisely,
it ends with what I would perceive if I could examine the
brain with physical and chemical means and methods.
The path ofinnerobservation begins with sensation and
goes as far as the construction of things from the material
of sensation. At the point of transition from brain process
to sensation, the path of observation is interrupted.
This way of thinking, which calls itself “critical ideal-
ism”—in contrast to the standpoint of naive conscious-
ness, which it calls “naive realism”—makes the error of
characterizing one percept as a mental picture, while ac-
cepting another percept in exactly the same way as the na-
ive realism it had ostensibly refuted. Critical idealism
seeks to prove that percepts have the character of mental
pictures, while naively accepting the percepts of one’s
own organism as objectively valid facts. What is more, it