Sabrina (Beishi) Hao

"What are scientists talking about when they talk about particles?" (in review)

In this paper, I explore the relation between actual scientific practice and conceptual interpretation of scientific theories by investigating the concept of particles in non-relativistic quantum mechanics (NRQM). I show that in actual scientific practice, scientists talk about ‘particles’ such as ‘electrons’ and ‘protons’ all the time. And I argue that this specific linguistic behavior is crucial to the scientific success that they bring about. Yet on the other hand, it is often suggested in ontological interpretation of NRQM that particles do not exist. There is a deep discrepancy, in the current scientific and philosophical literature, between how scientists talk about quantum theories and how philosophers propose to understand them.

This paper aims to bridge such gap. It has been explicitly argued and, for most of the time, implicitly assumed in the philosophical literature that we do not need to take scientists’ talk seriously, since language in scientific practice does not yield a complete and coherent ontological theory. I argue that even so, language in scientific practice imposes a semantic constraint on every ontological theory we propose. In order to account for the scientific success scientists bring about, our ontological theories need to provide adequate theories of meaning for their language in practice.

        Following such argument, I discuss different types of semantic theories an ontological theory can provide for scientists’ particle talk. After that, I also develop detailed semantic accounts for several existing ontological theories of NRQM respectively, and discuss the conceptual challenges these theories are facing in order to account for scientists’ particle talk.

"Robustness of particles in quantum field theory" (in-progress)

In this paper, I aim to defend the existence of particles within the context of quantum field theory (QFT) by arguing that the notion of particles possesses a very high degree of robustness in empirical confirmation of QFT. I first raise objections to the standard account of ontological interpretation that is commonly assumed in the literature, and then propose a positive account based on robustness analysis on QFT's empirical success. I argue that if the existence of certain entities are strongly supported by empirical evidence, we are justified to hold a positive epistemic attitude towards the existence of such entities. Robustness analysis can help us determine how strongly our empirical evidence supports the existence of an entity. At last, I examine how exactly QFT is empirically successful, with a primary focus on scattering experiments, and discuss the particle concept within this context. I conclude that since all empirical confirmation of QFT in particle physics is through preparation and detection of particles, we are strongly justified to believe in the existence of them.

"Bottom-Up Realism about Quantum Particles" (in-progress)

As Chakravartty (2021) points out, there seem to be two different ways to be realist about scientific ontology. One is what we call the top-down approach: we mainly look at the mathematical, theoretical formalism of the empirically successful theories, and consider adequate ontological interpretation based on them. The other one is called the bottom-up approach: we look at what we are actually detecting and measuring in experiments, and consider what our empirical data might tell us about what there is. There has been a great emphasis on the first approach in the current philosophical literature, while the second approach is mostly neglected. 

In this paper, I defend the bottom-up approach to ontological commitments based on scientific success. It is also closely related to entity realism. I argue that one can form ontological commitments about unobservable entities without committing to the (approximate) truth of the underlying theories.

"(Un)Natural Kinds in Scientific Theories" (in-progress)

"Modeling Dao in Set Theory" (in-progress)

In this paper, I try to interpret the metaphysical theories in Dao De Jing with set theoretic concepts. 

I observe that Lao Zi thinks that all properties in the world is binary in nature—that a property can always be negated, such as beauty and not beauty, long and not long. This is similar to set-theoretical definition of properties in western philosophy, and the negation can be understood as the complement set. However, Dao, as the ultimate and eternal truth of the world, cannot be negated. Lao Zi does not seem to think that the ultimate falsehood of the world exists, but one only deviates further and further from Dao. Relating to set theory, Dao can be understood as the universal set that has the complement set as the null set. Metaphysically, Dao should be understood as the most fundamental concept, and it cannot be negated and thus is one-valued truth in nature; everything in the world with binary nature is derived from the Oneness of Dao. 

Note that there are two different concepts of truth here: one is Dao, which is one-valued and metaphysically prior; the other one is the ordinary truth, which can be negated resulting in falsehood, and is thus two-valued and metaphysically derived. Unlike western logic, this metaphysical and set-theoretical picture does not run into the problem of paradoxes, since a paradox requires the concepts of truth and falsehood, and Dao is metaphysically prior to the concept of negation, no paradox can be formulated to impair the concept of Dao as the universal set.