Abstract: Recent literature in the philosophy of physics has focused on the challenge of empirical incoherence: the threat that some theories would defeat the evidence in their favour. Since its initial introduction in reference to the so-called “bare theory” of quantum mechanics in the 90s (see Barrett 1996 and 1999, pp. 116–117), empirical incoherence has been discussed in relation to various domains of fundamental physics—from quantum gravity to a number of interpretations of quantum mechanics, from cosmology to thermodynamics. In Adlam (2025), the focus is extended to more general hypothesis in the philosophy of science such as objective chances, induction, fine-tuning, multiverses, superdeterminism, retrocausality, non-locality, contextuality, naturalness and the autonomy of scales. For each of these applications, the challenge follows from the specific ontological and epistemological implications of the theory or hypothesis under examination. In some cases, such as for proposals in quantum gravity and for wavefunction realism in quantum mechanics, the target is the so-called ‘disappearance of spacetime’; in others, as in observer-relative interpretations of quantum mechanics, the threat is of epistemic solipsism; in yet other cases, such as for many-worlds quantum mechanics, the theory potentially undermines the standard understanding of probabilities, and so on. Given such an internal variety to the debate, the question of how the different applications relate to each other arises. My proposal is to unify the discussion by letting formal epistemology inform our understanding of the challenge. By so doing, we can better specify the structural aspects of the problem, and its implications. In particular, one of the main distinctions internal to the family of epistemic defeaters, the one between rebutting and undercutting defeaters, carves out three three kinds of empirical incoherence: empirical theories can be self-rebutting, self-undercutting, or exhibit a combination of both kinds of self-defeat, giving rise to genuinely mixed cases. In my talk, I will introduce these three kinds of empirical incoherence and show how the main challenges of empirical incoherence put forward in the extant literature fall into each category. I will then look at some logical and pragmatical implications of adopting the distinction.
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Philosophy of Physics Graduate Lunch Seminar Convenors: Paolo Faglia, Gregor Gajic and Rachel Pederson
