Mauro Dorato

Debates about the ontological implications of the general theory of relativity have long oscillated between spacetime substantivalism and relationism. I evaluate such debates by claiming that we need a third option, which I refer to as “structural spacetime realism.” Such a tertium quid sides with the relationists in defending the relational nature of the spacetime structure, but joins the substantivalists in arguing that spacetime exists, at least in part, independently of particular physical objects and events, the degree of “independence” being given by the extent to which geometrical laws exist “over and above” physical events exemplifying them. By showing that structural spacetime realism is the natural outcome of a semantic, model-theoretic approach to the nature of scientific theories, I conclude by arguing that the notion of partial isomorphic representation is the most plausible candidate to connect spacetime models with reality.

In this essay I claim that thought experiments have invariably been very important to inquire into the foundations of natural science (in particolar physics). In particular, they have proved essential to test the stability of allegedly clear but ultimately contradictory concepts, that were nonetheless at the basis of widely shared scientific theories. By quickly reviewing some famous Gedankenexperimenten proposed by Einstein against the completeness of (Bohr’s interpretation of) quantum mechanics, I will try to ask how could they possibly have the critical role that they always had.

1.: In this paper I discuss Putnam’s view on time and the special theory of relativity. I first locate Putnam’s philosophical approach within a more general framework, essentially making reference to Sellar’s distinction between the scientific image and the manifest image of the world. I then reconstruct Putnam’s argument in favour of the reality of the future and the determinateness of truth-value for future tense sentences by showing that it is based on three premises that generate a contradiction. In the second part of the paper I discuss Putnam’s argument both by using later results belonging to the foundations of STR and quantum mechanics, and by invoking some conceptual analysis on the pseudo-predicate “is real”. Since I will show that the presentists/eternalists debate is ill-founded if regarded as ontological, I will conclude that it boils down to our different practical attitudes towards past, present and future.

The conceptual relation between objective becoming and the direction of time is explored by discussing an ontologically asymmetric notion of causation. It is claimed that such a notion, in terms of which Stein defined objective becoming in Minkowski spacetime, has either a purely metaphysical status or is reducible to physical concepts. In the former case, it is adequate for Stein's purpose but irrelevant to physical theories. In the latter, the causal asymmetry can be related to irreversible physical processes only in an extrinsic way. This dilemma creates additional difficulties both to a unified theory of the direction of time and to the project of making room for becoming in the physical world.

In the first part of this paper, I try to clear the ground from frequent misconceptions about the relationship between fact and value by examining some uses of the adjective “natural” in ethical controversies. Such uses bear evidence to our “natural” tendency to regard nature (considered in a descriptive sense, as the complex of physical and biological regularities) as the source of ethical norms. I then try to account for the origin of this tendency by offering three related explanations, the most important of which regards it as the outcome of an adaptation: if any behaviour that favours our equilibrium with the environment is potentially adaptive, nothing can be more effective for this goal than developing an attitude toward the natural world that regards it as a dispenser of sacred norms that must be invariably respected. By referring to the Aristotelian notion of human flourishing illustrated in the first part of the paper, in the second I discuss some ethical problems raised by mini-chips implantable under in our bodies. I conclude by defending the potential beneficial effects of such new technological instruments.

Temporal becoming is usually considered the essence of the concept of time. But in our century most physicists and philosophers have defended the view that becoming is dependent on the existence of conscious beings and that there is no ontological difference between past and future. I evaluate these related claims both in light of their conceptual implications and by bringing to bear our best spacetime theories. ;Since a mind-independent becoming should be grounded in an ontological, non-epistemic asymmetry between past and future, I discuss the philosophical motivations for various "non-full views" of the future in contrast to the view that the future is as real as the past. I present the disagreement between these views both in terms of what is and in terms of possession of a definite truth value, thereby distinguishing an ontological and a semantic formulation. A formal definition of the "tree model" of reality allows a clear distinction of the often conflated notions of 'determinate', 'determined' and 'stable', and helps to formulate the differences between the "non-full" views and the "full view" of reality. ;To settle the issue concerning these views, I bring into the discussion the special theory of relativity. I show that oft-discussed arguments against the openness of the future presuppose a clarification of the properties of the relation 'being determinate for', in particular symmetry and transitivity. Within STR, objective becoming can be defended at the cost of relativizing what is determinate to spacetime points, of making the relation of determinedness time-asymmetric, and of denying determinateness to spacelike-related events. ;I conclude by urging that mind-independent temporal becoming can find a more hospitable environment in some isotropic cosmological models of general relativity, a claim that has been unreasonably neglected. If the universe does not present causal anomalies, the proper time of a co-moving 'fundamental particle' can be made common to every other world line. The existence of such a cosmic time would make current scientific talk of 'cosmic evolution' and 'the future of the universe' non-metaphorical.