Alberto Corti

Reichenbach’s importance to the development of modern philosophy can hardly be overstated. However, many themes and arguments originally developed by Reichenbach are either overlooked or not properly credited to him. In this article, we discuss an important but often forgotten argument of Reichenbach against the Kantian notion of synthetic a priori. We first give a detailed historical reconstruction of the argument and discuss the mild conventionalism that Reichenbach developed following this argument. Then, we recast this argument in the modern language of General Relativity. We show that this argument is still relevant for a modern attempt at articulating the notion of synthetic a priori: Friedman’s relativised synthetic a priori.

The scientific literature on Wigner’s Friend extended paradox rapidly grew in the last years. A sign that Frauchiger and Renner (2018)’s argument caught an important point. Indeed, they conclude that either we must abandon the universal validity of quantum mechanics, or a certain kind of traditional objective knowledge is impossible. We investigate this contradiction through a logico-epistemic toolbox. We show that abandoning the transmissibility of knowledge, as proposed by many kinds of relational approaches to quantum mechanics, is a heavy epistemological renouncement. Perhaps, it is better to bite the bullet and accept Frauchiger and Renner’s contradiction, until a new revolutionary solution will appear.

The paper addresses the main meta-metaphysical question, i.e., whether it is possible to do metaphysics and, in the case of an affirmative answer, how should we do it? With such an aim in mind, we sketch the broad context in which these meta-metaphysical questions arose in the philosophical literature (§ 1); then, we present what we take to be the three most widespread conceptions of metaphysics that are available in the analytic tradition: the neo-Quinean (§ 2), metaphysics as the science of possibilities (§ 3) and metaphysics as the study of the fundamental structures of reality (§ 4). We criticise these positions throughout these paragraphs before cashing out our proposal (§ 5). Our interpretation aligns with the recently proposed approach known as ‘naturalised metaphysics’ but with crucial differences. In our view, metaphysics is not only constrained by physics; rather, it grows out from all empirical sciences. More precisely, it can be achieved using formal language and the analysis of the results of scientific theories.

Scientific realism is usually presented as if metaphysical realism (i.e. the thesis that there is a structured mind-independent external world) were one of its essential parts. This paper aims to examine how weak the metaphysical commitments endorsed by scientific realists could be. I will argue that scientific realism could be stated without accepting any form of metaphysical realism. Such a conclusion does not go as far as to try to combine scientific realism with metaphysical antirealism. Instead, it amounts to the combination of the former with a weaker view, called quietism, which is agnostic on the existence of mind-independent structures. In Sect. 2, I will argue that the minimal claim that brings together every scientific realist view is devoid of any metaphysical commitment. In Sect. 3, I will define metaphysical realism and antirealism. Such work will be instrumental in providing a more precise statement of quietism. Finally (Sect. 4), I will argue that assuming quietism, it is still possible to make sense of the debate between scientific realists and antirealists.

_The thesis investigates metaphysical models of spin as a physical property instantiated by microphysical systems as described in non-relativistic quantum mechanics. The thesis is dived into two parts. The first part concerns foundational issues in meta-metaphysics. In particular, the author defends a naturalized approach to metaphysics, according to which metaphysical investigations have to be motivated and supported by our current best scientific theories. Furthermore, it is argued that naturalized metaphysics is in tension with (standard presentations of) scientific realism, and possible ways out from the tension are outlined. In the second part, the author investigates how spin has to be metaphysically modelled. After having introduced how spin is characterised in non-relativistic quantum mechanics and which approach to the metaphysics of quantum mechanics is assumed, it is argued that scientific realists must commit to spin’s existence as a physical property. Then, the author introduces the recent debate on quantum indeterminacy, and he presents new arguments against a widely shared approach to such indeterminacy. In the last part of the thesis, the author introduces an original characterisation of spin as a property through the determinable-determinate machinery. Such metaphysical machinery is instrumental to present a taxonomy of possible metaphysical models. Finally, a new and original view about spin is introduced and it is defended as a genuine contender in the debate which deserves more attention from the literature._.

This paper aims to characterise properly entanglement as an external relation obtaining between multiple quantum degrees of freedom. In particular, we argue that the entanglement relation is a unique relation fully characterised by mutual information, i.e. a quantity standardly used as a measure of entanglement. This analysis leads us to propose a new metaphysical account of entanglement, which we call Relational Entanglement Tesseract. Such an account characterises entanglement for both bipartite and multipartite cases, and, at the same time, it satisfies what we argue are three important desiderata of any metaphysical account of entanglement.

A common assumption in non-relativistic quantum mechanics is that self-adjoint operators mathematically represent properties of quantum systems. Focusing on spin, we argue that a natural view considers observables as determinable properties and their eigenvalues as their corresponding determinates. We provide a taxonomy of the different views that one can hold, once it is accepted that spin can be modelled with the determinable-determinate relation. In particular, we present the two main families of views, dubbed Spin Monism and Pluralism, and we show that the current literature does not take a stance between the two. Then we put forward two arguments in favour of the former. Finally, we present a new account of Spin Monism, that is absent in current literature; such a view is worth discussing, or so we contend, because several compelling considerations support it, and it opens new ways of thinking about the ontology of quantum mechanics.

It has been argued that non-relativistic quantum mechanics is the best hunting ground for genuine examples of metaphysical indeterminacy. Approaches to metaphysical indeterminacy can be divided into two families: meta-level and object-level accounts. It has been shown :27–245, 2010. https://doi.org/10.1080/00048400903097786; Skow in Philosophical Quarterly 60:851–858, 2010) that the most popular version of the meta-level accounts, namely the metaphysical supervaluationism proposed by Barnes and Williams, fails to deal with quantum indeterminacy. Such a fact has been taken by many as a challenge to adapt supervaluationism to quantum cases. In this paper, I will focus on the very last of these attempts, i.e. the situation semantics account proposed by Darby and Pickup. After having shown where quantum indeterminacy arises and having surveyed the assumptions endorsed by the participants of the debate, I turn to Darby and Pickup’s proposal. I argue that, despite the machinery introduced, their account still fails to account for quantum indeterminacy. After considering some possible counterarguments, I suggest in the conclusion that one can plausibly extend the argument to those meta-level approaches that treat quantum indeterminacy as worldly indecision.

Scientific realism is usually presented as if metaphysical realism (i.e. the thesis that there is a structured mind-independent external world) were one of its essential parts. This paper aims to examine how weak the metaphysical commitments endorsed by scientific realists could be. I will argue that scientific realism could be stated without accepting any form of metaphysical realism. Such a conclusion does not go as far as to try to combine scientific realism with metaphysical antirealism. Instead, it amounts to the combination of the former with a weaker view, called quietism, which is agnostic on the existence of mind-independent structures. In Sect. 2, I will argue that the minimal claim that brings together every scientific realist view is devoid of any metaphysical commitment. In Sect. 3, I will define metaphysical realism and antirealism. Such work will be instrumental in providing a more precise statement of quietism. Finally (Sect. 4), I will argue that assuming quietism, it is still possible to make sense of the debate between scientific realists and antirealists.