Julien Tricard

Comparativists (about mass) eliminate absolute masses from the fundamental ontological picture by virtue of a principle of economy, the “Comparative Razor”, which requires that only mass-relations, that are invariant under (metrical) symmetries be considered fundamental. I show how this weapon backfires. If mass-relations are endowed with a standard (multiplicative) concatenation structure, power-transformations become (metrical) symmetries, leaving comparativists prima facie unable to distinguish a possible world and its duplicate where mass-relations are uniformly squared. Then, I considered possible exit strategies, which unfortunately either rely on hidden absolutist assumptions, or leave comparativists and absolutists on equal footing.

On peut s'etonner qu'un concept aussi central en philosophie des sciences et aussi courant dans le langage scientifique puisse faire encore l'objet d'une question de definition. Pourtant, la signification du concept de "loi de la nature" reste encore obscure, car traversee par une ambiguite fondamentale. Si l'existence de "lois" ratifie le fait que la nature est reguliere, cela signifie-t-il dire que les lois sont de simples regularites, c'est-a-dire des rapports constants entre faits? Ne seraient-elles pas plutot des "regles" qui gouvernent necessairement le cours des phenomenes? Mais alors, quel est le fondement de cette necessite que ces reglent imposent aux faits : derivent-elles de la nature et des dispositions des choses, ou bien sont-elles octroyees de l'exterieur par une instance (divine ou transcendantale) qui legifere sur la nature " comme un roi en son royaume "?

In _The Large-Scale Structure of Inductive Inference_, Norton builds on his 2021 book and brings a masterful completion to the whole project of the material theory of induction (MTI). I am sympathetic to the project and already quite convinced by the core claims of the MTI, especially the claim that all inductive inferences are materially, and not formally, warranted. Reading the 2024 book nevertheless made me wonder about two things. The first point of discussion is “theory-internal” and deals specifically with Norton’s treatment of the circularity threat. My second point is more general and external. It concerns the problem of induction, which Norton claims to have dissolved. I am not going to challenge this claim head-on, but simply suggest that it calls for external additions from the metaphysics of science (which is my home discipline).

This paper engages with the metaphysical debate between Absolutism and Comparativism about mass, addressing the question of whether massive objects possess their masses intrinsically (as absolute magnitudes) or only relationally, through their mass relations to other objects. In the current debate, comparativists argue that the dimensional nature of mass renders absolute magnitudes undetectable and redundant, forcing absolutists to rely on arguments about the dynamic relevance of absolute masses in physical laws. I advance a novel defence of Absolutism by appealing to contemporary metrology, particularly the role of the Kibble balance and the redefinition of the kilogram in terms of the fixed numerical value of Planck’s constant. I argue that absolute masses are metrically detectable, independently of their dynamic relevance, thereby challenging the claim that dimensional quantities are kinematically comparative. Additionally, I provide a solution to the Ozma games, showing how the meaning of our mass values (like ‘1 kg’) can be communicated to extra-terrestrial intelligences through the operational universality of the new SI definitions.

Relationalism is the view that a quantity (i.e., space or mass) consists only of a network of concrete objects that stand in determinate relations (spatial relations or mass-relations). At its very core, the theory claims that an object possesses a determinate quantity fundamentally by standing in determinate relations in that quantity to other objects. For instance, my laptop’s mass consists fundamentally in the fact that it is k times more or less massive than other objects (my neighbor’s car, the Earth, the International Prototype of the Kilogram). The view is nominalistic insofar as, according to it, facts about quantities are fundamental facts about particulars (that they are so and so related) and not about their attributes (like quantitative universals or positions in abstract state spaces). I offer here an argument against this theory, which I call “ultimate” (borrowing Bird’s (2005) term) because it shows that the very core of this theory fails to account for what it is supposed to account for: the fact that objects possess determinate quantities. I show that by merely situating objects in relation to each other, it fails to situate them anywhere really, that is, to endow them with well-determined quantities.

Que sont les « lois de la nature » que les sciences empiriques, et en premier lieu la physique, tentent de saisir? Et si les scientifiques ne peuvent les découvrir, ou du moins les confirmer, que sur la base de l’expérience, quels sont la nature et le fondement de leurs opérations inductives? Comment garantir la possibilité d’une authentique connaissance de ces lois qui structurent la réalité? Ce livre propose une enquête épistémologique et métaphysique au cours de laquelle deux fils directeurs s’entremêlent. Il s’agit d’une part de s’interroger sur la nature ontologique des lois, à partir des débats contemporains en philosophie analytique des sciences. Les lois de la nature sont-elles, comme le pensent les empiristes humiens, de simples régularités factuelles universelles? Ou bien devraient-elles être conçues comme des faits nomiques d’un autre ordre, capables de rendre nécessaires les régularités que nous observons? Il s’agit d’autre part de remettre sur le métier le problème classique de l’induction que nous héritons de Hume. L’induction n’est-elle que l’opération de généralisation qualitative à partir de l’expérience? Exige-t-elle, comme on le suppose souvent, de montrer que la nature est uniforme et que les lois sont stables dans le temps? Pour résoudre ces problèmes, nous développons une théorie inédite des lois, centrée sur l’analyse de leur nature quantitative, et proposons un fondement nouveau à l’induction scientifique, qui repose sur l’existence, dans la réalité physique, de structures quantitatives. Nous montrons ainsi que c’est la possibilité d’appliquer les mathématiques, dans la formulation des lois physiques, qui garantit la connaissance inductive.

Within the metaphysics of quantity, the debate rages between Absolutism and Comparativism. In retrospect, Armstrong appears to be an absolutist, for he claims that magnitudes like being 1 kg in mass are intrinsic properties of particulars, in virtue of which relations like being twice as massive as hold. More importantly, his theory is an instance of what I call ‘Radical Absolutism’ (and the only on the market), for he does not merely argue that relations are grounded in magnitudes, but also (and quite admirably) tries to explain how they “flow from” (his words) the intrinsic features of magnitudes. The goal of the paper is not to support his theory, but to better understand why it fails, and why this must be of concern to contemporary absolutists.

Among those who posit properties, liberals (mostly nominalists) admit abundant, ontologically free properties, which particulars possess whenever they satisfy the same predicate and belong to the same class, however artificial. I call them “L-properties” (for “Liberal”). Some liberals also admit that some few L-properties are natural, while most of them are artificial (the same applies to the corresponding classes). Others (mostly but not only realists) commit to a more discriminating use of the category: properties are sparse, they make for the objective similarities among particulars, and more importantly, they allow to analyze “objective similarity” and “class naturalness” in terms of property-possessing and sharing. They give particulars their “true nature”, and I call them “A-properties” (for “Analytical”). This article provides a defense of this second type of properties, in the particular case of sortals. To that end, a new fact is put forward: that sorts are classes which are natural not as a primitive feature, but in virtue of what the particulars which belong to them are, and which makes them _naturally belong_ to them. I then argue that this fact entails the existence of the desired type of properties, “sortal A-properties”, although leaving open the question of how they should be construed.

Julien Tricard criticizes the traditional formulation of the Problem of Induction, and offers to simplify it. Since Hume, he oughts to demonstrate that “the same causes always produce the same effects”, or that “the laws of nature cannot change over time” (uniformity of nature). First, an historical analysis shows, however, that the notion of causality is not needed to set the problem out. Second, the concept of “laws of nature” is analyzed, proving that laws cannot change over time: either there are unchanging laws in nature, or there is none. Therefore, it is necessary and plainly sufficient, in order to solve the Problem of Induction, to prove that laws of nature, governing natural phenomena, do exist.

By analyzing the successful prediction of the Ω− particle by M. Gell-Mann and Y. Ne'eman (in 1962), I bring to light a so far unexamined role of symmetries in physics. Symmetries within a family of objects or states (here, strongly interacting particles) may be used not only to classify the discovered ones, but also to predict the existence of unobserved ones, as instances of a nomological conjecture. To this end, I criticize previous accounts of Ω−’s episode as involving abductive reasoning or a very problematic, Pythagorean “Reification Principle” (Bangu, 2008), or as a case of heuristic reasoning (Ginammi, 2016; Bueno & French, 2018). I show that an adequate reconstruction of the episode relies on a principle according to which symmetric elements of a mathematical representation must be jointly interpreted, provided that a structuralist, background assumption is made on the represented physical system. I finally show that this rule reveals a nomological use of symmetries, which are used to bring together different states or objects as instances of the same law and to predict unobserved instances, such that mathematics—here, Group Theory—provides us with induction instruments to expand our knowledge of the physical world.

When Goodman put forward his “New Riddle of Induction”, he distinguished if from the old problem of justifying the so-called “Principle of Uniformity of Nature”: proving that the future will resemble the past, and that still standing lawful regularities will continue to hold. He intended to break with these ancient questions, while asking about lawlike generalizations and projectible predicates instead: how are we to separate those generalizations which are rightfully confirmed by their observed instances (i.e. nomological) and those accidental ones which are nonetheless empirically equivalent? One shall not seek a ground for induction anymore, but a criterion for nomological hypothesis. Therefore Goodman’s claim seems twofold: (A) one has to face a second problem of induction, which is distinct from the old one while genuinely being a problem about induction, and (B) this new problem is solvable by a criterion of empirical confirmability, which discriminates nomological from accidental generalizations. We claim that one cannot genuinely (A) face this new problem of induction while (B) looking for such a criterion. Indeed, we argue, when one compares several hypothesis or generalizations on the same observational basis, then they must appear as equally nomological. Conversely, if one is considering hypothesis or generalizations which are not equally nomological, then one is actually unable to compare them on the same observational basis, hence to formulate the “New Riddle”. Therefore the issue raised in (A) cannot be adequately solved in (B). Yet we do accept the claim (A) that a new and distinct problem of induction is to be confronted. Thus we deny that (B) offer an adequate type of solutions to this problem, which we shall finally formulate in a more suitable manner.

Julien Tricard tackles the abductive solution to the problem of induction. In order to best explain the regularities that can be observed in nature, should one assume that they necessarily result from natural laws, without which they would be improbable cosmic coincidences? By examining David Armstrong's and John Foster's versions of this inference, Julien Tricard shows that it is based on the confusion of two incompatible concepts of “regularity”. From this he derives a conception of induction that is neither the empiricists’ factual generalization, nor the abduction of nomic necessities from observed regularities, but the operation of constituting particular facts as regular instances of laws.