Editing Franz Brentano (section)

===Theory of perception===
He is also well known for claiming that ''Wahrnehmung ist Falschnehmung'' ('perception is misconception') that is to say perception is erroneous. In fact he maintained that external, [[sensory perception]] could not tell us anything about the ''de facto'' existence of the perceived world, which could simply be illusion. However, we can be absolutely sure of our internal perception. When I hear a tone, I cannot be completely sure that there is a tone in the real world, but I am absolutely certain that I do hear. This awareness, of the fact that I hear, is called internal perception. External perception, sensory perception, can only yield hypotheses about the perceived world, but not truth. Hence he and many of his pupils (in particular [[Carl Stumpf]] and [[Edmund Husserl]]) thought that the natural sciences could only yield hypotheses and never universal, absolute truths as in pure [[logic]] or [[mathematics]].

However, in a reprinting of his ''Psychologie vom Empirischen Standpunkte'' (''Psychology from an Empirical Standpoint''), he recanted this previous view. He attempted to do so without reworking the previous arguments within that work but it has been said that he was wholly unsuccessful. The new view states that when we hear a sound, we hear something from the external world; there are no physical phenomena of internal perception.<ref>See Postfix in the 1923 edition (in German) or the 1973, English version ({{ISBN|0710074255}}, edited by Oskar Kraus; translated [from German] by Antos C. Rancurello, D. B. Terrell and [[Linda López McAlister]]; English edition edited by Linda López McAlister).</ref>