Resumen:
|
In this disssertation we argue against the possibility of defining a notion of conditional probability in quantum theory, both at a mathematical and physically meaningful level. We defend that the probability defined ty the Lüders rule, the only possible candidate to play such a role, cannot be interpreted as such. This claim holds wheter quantum events are interpreted as projection operators in an abstract Hilbert space, as the physical values associated to them, or as measurement outcomes, both from a synchronic and a diachronic perspective. The only notion of conditional probability the Lüders rule defines is a purely instrumental one. In addition, we show that the unconditional quantum probabilities can also be interpreted as probabilities only under a purely instrumental perspective, where the difficulties in interpreting them non-instrumentally are, ultimately, the same as those we encounter in giving a non-instrumental conditional interpretation of the probability defined by the Lüders rule.
We frame this discussion within the general issue of conceptual change in science and show how, generally, the fact that two concepts are co-extensive in their shared domain of application - as the probability defined by the Lüders rule and classical conditional probability are for compatible events- does not guarantee that the more general concept is a conceptual extension of the more limited one. To give an appropriate account of concepts extension, we show that concepts present an "open texture" that does not allow for a set of jointly necessary and sufficient conditions to characterize an extended concept, and thus formulatea new account, namely the "Cluster of Markers account", in terms of a cluster of markers which are expected to hold for the extended concept. This account, we argue, can capture the complexity involved in actual cases of conceptual change in science and can account for the fact that there are concepts which, even if coextensive in their shared domain of application, do not share enough meaning to justify regarding them as defining the same concept.
|