FUNCTIONAL RELATIONS AND CAUSALITY IN FECHNER AND MACH
In the foundations of Fechnerâ€™s psychophysics, the concept of â€œfunctional relationâ€ plays a highly relevant role in three different respects: (1) in respect to the principles of measure- ment, (2) in respect to the mind-body problem, and (3) in respect to the concept of a law of nature. In all three cases, it is important to explain the difference between the functional de- pendency of one variable upon another, on the one hand, and the causal relationship between variables on the other. In all three respects, Ernst Mach developed Fechnerâ€™s ideas further and tried to extend the lessons of psychophysics learned through the concept of a functional relation to the whole of science. For all three cases, I try to indicate why they are still rele- vant for psychophysics today.