ua nt - p h / 97 09 05 9 v 2 2 7 A ug 1 99 8 Against Measurement ? – On the Concept of Information 1

In his last article Against ‘Measurement’ J. S. Bell sums up his well known critique of the problem of explaining the measurement process within the framework of quantum theory. In this article I will discuss the measurement process by analysing the concept of measurement from the epistemological point of view and I will argue against Bell that it belongs to the preconditions of experience to necessarily end up with a ”reduction of the wavefunction”. I will consider the ”chain of reduction” in detail – from pure states of S ⊗A (system S and measuring apparatus A) via different kinds of mixtures to pure states of A(S). It turns out that decoherence is not sufficient to explain reduction, but that this can be done in terms of the concept of information within a transcendental approach.