In 2021, our Department of Philosophy admitted a PhD cohort composed entirely of nonbinary students. As that cohort, we offer our experiences as a case study, with two aims. First, we investigate and provide examples of the particular kinds of epistemic injustice perpetrated against nonbinary philosophers, and second, we highlight one antidote to this epistemic injustice: communities of epistemic sanctuary. Toward these ends, we offer narrative accounts of three distinct experiences over our first year as PhD students. We discuss how our nonbinary community of three provided insulation against the alienation nonbinary philosophers face in academia. Furthermore, this insulation had a distinctly epistemic hue. Therefore, we argue that developing communities of epistemic sanctuary combats the epistemic injustice that disenfranchises trans thinkers in our field.

Bare Everettian quantum mechanics (EQM) suggests that for any quantum mechanical process, all possible outcomes obtain. On first inspection, EQM appears to lend itself well to many worlds interpretations. However,  this approach requires the metaphysical commitment to a form of modal realism. In response to this concern, I propose a single-world Everettian universe. On my model, the complete branching structure itself is a metaphysically possible world. To solve the problem of identity in a single world where all possible outcomes obtain, I propose that in addition to the mereological concepts of material and temporal parts, branch-like parts exist. I then use a self-locating approach to treating probabilities as the credences of a rational agent, where the probability of some outcome corresponds to branch weight. This one-world model thus has the capacity to reproduce the predictions of the Born rule while addressing concerns over the apparent frivolity of many-world interpretations.

Since it neither relies on a collapse postulate, nor posits a hidden variable, Everettian quantum mechanics (EQM) has emerged as an attractive option among the various realist interpretations of quantum mechanics. In this sense, EQM is a simpler theory than its competitors. However, it appears to be quite a bit more complex, ontologically speaking; unlike its competitor theories, EQM has been taken to entail a plethora of worlds. This paper concerns perhaps the most prominent metaphysical objection raised against EQM: that of ontological extravagance. 

Everettians have given this objection little serious attention. For instance, Wallace (2012) dismisses this objection as relying on a misinterpretation of Ockham’s razor. Where Ockham’s razor merely concerns the economy of postulates and the overall intricacy of our body of theory, Wallace insists that his skeptic instead appeals to a new criterion, under which we ought to minimize the size of the universe that our theory posits. Contra Wallace, I argue that the objection does not rest on a misinterpretation of Ockham’s razor, but on a different scientific norm altogether: the minimum divergence norm, as advocated by Emery (2017, 2023). 

According to the minimal divergence norm (MDN), we ought to prefer theories that deviate least from the manifest image, or the way we generally perceive the world to be. For any pair of equally empirically adequate and explanatorily useful theories, then, we ought to prefer the theory that posits the physical reality most closely aligned with our perception of physical reality. Here I diverge from Emery; it is a step too far to assert that there is some image of the world that is the manifest image. After all, observations themselves depend on our theoretical commitments. While EQM does not necessarily posit that the world itself is vastly different from how it appears, it is generally taken to entail many more worlds than its competitor theories. The heart of the objection is this: EQM demands an over-abundance of concreta beyond what we perceive when we look at the world; indeed, for each concrete object we observe, EQM is taken to entail many more such objects, each in a distinct world. On this metaphysical view of EQM, then, that which there is vastly diverges from what we observe, in a dramatic departure from the manifest image. Assuming that we ought to endorse the MDN, this objection poses a serious issue for Everettians committed to a many worlds ontology. 

In this paper, I first present a stronger version of this objection than has been previously articulated. Second, I use this objection to evaluate the most prominent competitor ontologies of EQM, demonstrating that it condemns only those approaches that involve many worlds.

Everettian quantum mechanics (EQM) posits that the global wave function evolves unitarily without collapse; decoherence ensures that all events possible under stochastic theories obtain, each along distinct branches. However, it is unclear how to reason about properties in EQM. In collapse theories, one typically employs the eigenstate-eigenvalue link (EEL), which states that for some property A of a system, there is a self-adjoint operator  with eigenstates |a_i⟩ and corresponding eigenvalues a_i. The system determinately has property A_ j represented by the eigenvalue with real numerical value a_j iff it is in the eigenstate |a_ j ⟩. If we suppose that EQM offers a true description of the world, the lack of collapse to determinate properties makes it unclear how we ought to represent properties that appear determinate to agents. Any particle sent through an inhomogeneous magnetic field will be deflected either up or down, suggesting that post-decoherence, along each branch the particle has at most one of the properties “spin up” or “spin down.” Since EQM is incompatible with EEL, how ought we make sense of this given that the Everettian branches themselves are emergent from the more fundamental global wave function that governs the evolution of all branches? Missing from modern conceptions of EQM is a principle that explicitly links the mathematical formalism to observed physical properties. In this paper, we explore the possibility of adapting EEL from orthodox quantum mechanics to suit the needs of EQM, and we ultimately present a branch-relative EEL. We first interrogate the existent arguments against EEL in EQM, and show that the scope of these arguments is substantially less far-reaching than previously presumed. Our second objective is to illustrate the theoretical value of an extension to EEL as a useful link between the mathematical formalism of EEL and physical reality.

There has been a lot of productive discussion about what Bohr’s philosophy of complementarity says. We focus instead on its historical role in pedagogy and research, focusing on relationships between research leaders and their students (mentors and mentees, for short). We find that complementarity is characteristically associated with a particular form of bad epistemic behavior: epistemic infringement, where a mentor systematically contravenes the social and epistemic norms that usually govern their relationship with mentees in a manner that encroaches on the epistemic agency of the latter.  

We argue that Bohr sets the template for this social function of complementarity when he introduces the philosophy in his Como lecture of 1927. Characteristic of epistemic infringement is the abuser’s appeal to the very norms being violated to justify their violation. To illustrate this concept, imagine Sarah, a graduate student, wants to go to a prestigious conference but lacks the funds; her mentor, Peter, offers to cover all her fees if she keeps the source of the money a secret. Peter chides Sarah when she declines the offer, noting that she is shooting herself in the foot: she needs to go to conferences like these to gain scholarly independence. Of course, Peter’s offer would increase Sarah’s reliance on him by establishing a shared secret, contravening the independence norm. Similarly, Bohr appeals repeatedly to the underdetermination of theoretical analogy (particle or wave?) by experiments available at the time of his writing, urging restraint in committing to one of them—a norm which is well-recognized and widely endorsed today among philosophers of physics. Nonetheless, Bohr uses this appeal to argue that physicists should not work with any analogy: only the Copenhagen school’s formally-defined theory can be used with confidence, he argues, and no visualizable depiction of the quantum world is possible. This talk of the finality of the Copenhagen picture is what Mara Beller has memorably deemed Bohr’s “rhetoric of inevitability.” Our assessment goes one step further, suggesting that this rhetoric served a powerful psychological function: to wit, undermining the agency of would-be opponents and dissenters to the Copenhagen paradigm. 

This function becomes clearer when we analyze cases where research leaders like Bohr appeal to complementarity in their relationships with more junior scientists. We focus on two historical case studies: the relationship between Heisenberg and Bohr from 1926 to 1935, and the relationship between Wheeler and Everett around the time of the former’s trip to Copenhagen to advertise his student's work. In both cases, we argue, the mentors succeed in pressuring their students to abandon pursuing their original interpretations of their work—interpretations which, when later resuscitated, proved to be immensely fruitful for the field. We close by reflecting on how these relationships deviate from Carl Rogers’s positive model for healthy mentorship.