Meeting 3: Kévin Chalas and Núria Muñoz Garganté on Time, Emergence and Reduction
Channel: CEFISES at UCLouvain
Date: 2021-06-13

Recorded online, May 26, 2021. Abstracts of the two talks:

Kévin Chalas - There is no problem of time or change in general relativity

Applying the constrained Hamiltonian formalism to general relativity (GR), as recommended by canonical quantum gravity programmes, leads to the “problem of time”, actually a problem of change. Earman (2002) argues in response that abandoning change is necessary for recovering determinism in GR. However, following Dieks and Healey I dismiss this tradeoff between change and determinism and argue for a genuine change in GR.

First, I suggest to understand change and its associated time as local notions. The indeterminism of the Hamiltonian formalism is then interpreted as a genuine choice of gauge, teaching us that no observable change depends on having a global time function. Local definitions thus preserve the possibility of predictions for GR, while Earman’s insistence on global determinism becomes unnecessary and threatens GR with empirical incoherence.

I then address a greater threat to genuine change, which comes from understanding objects as successions of instantaneous events. I suggest that new developments in synthetic differential geometry could help with describing truly continuous worldlines for objects.

Finally, I note that the defence of genuine change at the classical level of GR highlights the problem of its possible emergence from quantum gravity. This problem requires us to rethink emergence in new ways, as it is the emergence of time itself that is at play.

Núria Muñoz Garganté - Inter- and intra-category forms of compatibility between emergence and reduction in philosophy of science

In contemporary philosophy of science it is typical to oppose emergence and reduction. This account is problematic for two reasons. First, it does not allow for a positive definition of emergence, without it being coupled to (a failure of) reduction. Second, it does not align with scientists' intuitions about emergent phenomena and their majoritarian acceptance of scientific reductionism.

These problems call for rethinking emergence and reduction as compatible with each other. In my talk I will use a framework by Guay and Sartenaer to introduce two forms of compatibilism: inter-category and intra-category. For instance, inter-category compatibilism obtains when emergence is epistemological and reduction is ontological, while intra-category compatibilism obtains when either is epistemological. I will discuss examples of either form of compatibilism and will argue in favour of intra-category compatibilism.