Andrea Reichenberger
Technical University of Munich
Philipp Berghofer champions a phenomenological experience-first epistemology und he argues for the justificatory force of experiences. The significance that experience has for our everyday lives seems indisputable. Experience is so much a part of everyday life and everyday language that it seems futile to argue against this statement. The situation is obviously somewhat different when it comes to justifying experience in sciences, in particular in quantum mechanics. To quote Philipp Berghofer: “modern physics suggests that the world as we experience it is mere illusion.” Berghofer argues against this view and takes sides with QBism, a position which “embraces the idea that the concept of experience is fundamental to understanding science in general and quantum mechanics in particular. For QBists, the quantum state (i.e. the wave function) does not represent objective reality but instead represents an agent’s subjective degrees of beliefs about her future experiences.” I have, admittedly, some difficulties understanding the meaning and purpose of such discussions. For me, highly phlosophical terms and topics such as “experience”, “justification”, “consciousness”, “reality”, “illusion” et al. are big names with a long history and a wide range of possible meanings. Every physics and maths teacher knows how misleading students’ everyday experience can be when it comes to calculating acceleration when driving a car. Today we live in a highly technical and standardised world in which many things are and must be intersubjectively measurable, calculable and formalisable. Calculation errors can have fatal consequences here. Mistakes are made by people; the art and tchnique of computing and programming, of logic and reasoning are kinds of cultural practices. It is of little help to victims of a bomb attack when philosophers claim that the world is just an illusion or simulation. What mockery and derision towards the victims! This somewhat cynical attitude concerning philosophical debates brings me to what I think is a key point made by Philipp: “We must respect the phenomena,” Philipp says. “Please, do not explain them away!” Interestingly, this is a plea to the ethics and morals of the philosophical discussion. However, the “experience first”-thesis does not help to understand the underlying problem here, i.e. the wave function concept. In quantum physics, a wave function is a mathematical description of the quantum state, composed of complex numbers. Wave-functions are necessary to derive predictions, but do not themselves correspond to anything observable. An observable is a physical property or physical quantity that can be measured. So are wave-functions real or not? To understand this, one have to understand a lot about the quantum mechanical formalism, about the role of complex numbers and the Hilbert space formalism, just to give a few examples. Is the know-how of calculating with complex numbers, which has become indispensable for quantum computing, part of everyday life experience? Perhaps, with regard to mathematicians, physicists and programmers who are specialised in this research field. Let me conclude with a plea on my part to the current discussion: Be a little more careful when using terms. Try to clarify what you mean by them. But also realise that every precision has its price: a simplification, a narrowing of possible perspectives. Every theory has its price. None explains everything, nor does it have to. Be pragmatic and open to other approaches, theories, opinions and points of view. And finally stop focussing philosophical discussions about quantum physics on the Anglophone, Western, male-dominated discourse of a few philosophers. And do not close your eyes to the technological developments of quantum physics towards quantum computing as a cultural practice, promoted and controlled by politically powerful states and institutions, often based on vague prospects and strategies for responsible technology assessment. These are big future challanges beyond the olf-fashioned subject-object problem. From this standpoint, agency always operates within and through a social structure and cultural practice. Really? What drives whom? Is every kind of agency a human agency? Is every human agency a responsible agency? Last, but not least: What is meant by “agency” in quantum physics? It seems to me that there is still a great need for clarification here.