I examine the relation between naturalistically motivated and other critiques of grounding and similar critiques of the contrast between A- and B-theoretic views of time. I argue that even the combined dialectical upshot of nonunity objections in the latter case is not what it is in the former. I sympathetically discuss the objection that the notion of grounding is not intelligible and part of ‘esoteric’ metaphysics; this objection turns out to be just as serious in the case of the A/B (...) contrast. I then consider whether grounding is needed to draw the A/B contrast in the first place and answer this question in the negative. Finally, I comment on the costs of esotericism in both cases. (shrink)

This is an invited commentary on "Physical Time within Human Time" (Gruber, Block, & Montemayor, 2022) and "Bridging the Neuroscience and Physics of Time" (Buonomano & Rovelli, 2021). I’m very sympathetic to aspects of each proposal. In this article, I offer some comments, starting with (Buonomano & Rovelli, 2021).

This article proposes a “third way” in the philosophy of time beyond A-theory and the block universe, in which time is understood as a purely local phenomenon. It does so by starting with simple metaphysical assumptions about substances and their properties. Based on these assumptions, the notions of “before”, of change, and of time as local quantification of change can be derived non-circularly, i.e. without invoking temporal concepts. I then proceed to prove the irreversibility of local time by showing that (...) the propositional content of the local past cannot be changed, since this would imply a contradiction, whereas that of the future can. Time’s familiar asymmetric character, in particular the difference between the fixed past and the open or “branching” future, is therefore a non-illusory but purely local phenomenon. Such a model requires no past-present-future distinction valid for the entire cosmos, and is therefore consistent with special and general relativity. (shrink)

Presentism is, roughly, the metaphysical doctrine that maintains that whatever exists, exists in the present. The compatibility of presentism with the theories of special and general relativity was much debated in recent years. It has been argued that at least some versions of presentism are consistent with time-orientable models of general relativity. In this paper we confront the thesis of presentism with relativistic physics, in the strong gravitational limit where black holes are formed. We conclude that the presentist position is (...) at odds with the existence of black holes and other compact objects in the universe. A revision of the thesis is necessary, if it is intended to be consistent with the current scientific view of the universe. (shrink)

Is reality three-dimensional and becoming real (Presentism), or is reality four-dimensional and becoming illusory (Eternalism)? Both options raise difficulties. I argue that we do not need to be trapped by this dilemma. There is a third possibility: reality has a more complex temporal structure than either of these two naive options. Fundamental becoming is real, but local and unoriented. A notion of present is well defined, but only locally and in the context of approximations.