In rejecting (B3), the A-theorist is committed to temporal nonlocality. This will be a bitter pill to swallow, as temporal nonlocality runs counter to what has traditionally been the philosophical and scientific orthodoxy. Indeed, temporal locality is ‘almost ubiquitous in the way that scientists think about science and about what constitutes a reasonable scientific hypothesis’ (Adlam 2018: 41).
Temporal locality, and spatiotemporal locality more generally, certainly has a long line of supporters. Take Hume, for instance, who famously claimed that ‘nothing can operate in a time or place which is ever so little remov’d from those of its existence’ (1740 [1992]: 75). Or Newton, who displays a more scathing attitude towards nonlocality:
That one body may act upon another at a Distance thro’ a Vacuum, without the Mediation of anything else, by and through which their Action and Force may be conveyed from one to another, is to me so great an absurdity, that I believe no Man who has in philosophical Matters a competent Faculty of thinking can ever fall into it. (Newton [in Cohen 1978: 302-3])
Certainly, nonlocality – both temporal and spatiotemporal – is highly unintuitive. In their discussion of velocity, Bigelow and Pargetter (1989) offer something of a justification.
9 I allow for the sake of argument that the notion of a chain of causal intermediary events is
For context: they are arguing in favour of the ‘flux doctrine’ (that velocity is a property intrinsic to instantaneous states of objects) as opposed to the ‘Ockhamist view’ (that velocity is attributable to an object merely in virtue of the positions it occupies at different times).
Consider for instance a meteor striking Mars, and consider the problem of explaining why it creates a crater of precisely the size it does. At the precise moment of impact, the meteor exerts a specific force on the surface of Mars. Why does it exert precisely that force? Because it is moving at a particular velocity. On the Ockhamist view, what this amounts to is that it exerts the force it does because it has occupied such-and-such positions at such-and-such times. In other words, the Ockhamist appeals to the positions the meteor has occupied in the past. But why should a body’s past positions exert any force now? This requires the meteor to have some kind of ‘memory’ – what it does on Mars depends not only on its current properties, but also where it has been […] This cannot be ruled out as absurd, without further argument. Nevertheless, it is an advantage of the flux doctrine that it does not require any pseudo-memory in objects, or any time- lag in causation. (Bigelow & Pargetter 1989: 296)
Their point is that we should reject the Ockhamist view because it entails the occurrence of temporally nonlocal interactions, which in turn seems to require the operation of some sort of spooky mechanism (‘pseudo-memory in objects’ or suchlike). Here, then, is an argument against temporal nonlocality: All things being equal, we should avoid spooky mechanisms.
Unfortunately for the B-theorist it is far from definitive. The A-theorist can simply reply that in the current context all things aren’t equal. Positing such ‘spooky’ mechanisms, unintuitive as doing so may be, is less unintuitive than what the counter-argument from experience is trying to establish – viz. that we don’t veridically experience A-change. And so they could use the unintuitiveness of the B-theory to motivate their rejection of temporal locality. Perhaps spooky mechanisms are a small price to pay if doing so means we can preserve something so fundamental to experience as the passing of time. It seems, then, that we will have to do better than simply appealing to intuitions if (B3) is to gain any traction.
Spatiotemporal locality might instead be defended on pragmatic grounds. The idea is that if we assumed that a state of affairs has as its immediate cause some spatiotemporally distant state of affairs, it would be impossible to isolate which aspects of which states of affairs were causally relevant to any other state of affairs. The worry is that this would
undermine the whole scientific approach, as we would have no reason to suppose that the variables changed during an experiment were responsible for its outcome. By assuming spatiotemporal locality, we restrict our attention to the variables changed during the experiment, and so are able to determine the effects of those variables. As Einstein writes in a letter to Born, without the assumption of spatiotemporal locality, ‘physical thinking in the familiar sense would not be possible’, and it would be ‘hard to see any way of formulating and testing the laws of physics’ (Born 1971: 172). Indeed, given that we do find regularities between spatiotemporally local states of affairs, rejecting locality would seem to leave it ‘completely mysterious why the effects of a cause occur at the time and place that they do’ (Le Poidevin 2007a:21).
We might wonder whether these worries aren’t somewhat overstated, however. Certainly, it’s hard to imagine how we could even begin to go about developing a physics in a world that was properly described by laws which eschewed spatiotemporally local interactions. Of course, in such a world we would have to accept nonlocality. But we could accept nonlocality under less extreme circumstances. All nonlocality requires is that nonlocal causal interactions are possible; nonlocality could be true and it nevertheless be the case that interactions are for the most part local. All we would need is a theoretical framework that was able to predict under what circumstances interactions would be local and those circumstances under which interactions would be nonlocal. If we had such a framework, there would be nothing mysterious about why some interactions were local and others not. What’s more, we have such a framework – at least, we have one that apparently predicts spatially nonlocal interactions: quantum mechanics.
In 1935, Einstein, Podolsky, and Rosen (EPR) proposed a thought experiment designed to show that quantum theory was, as it stood, incomplete. A simplified version of the experiment is owed to Bohm (1951), the broad strokes of which are as follows. Two entangled particles are emitted from a source in opposite directions towards spin detectors. The measurements are synchronous (or near synchronous) so as to preclude any slower-than-light signal from one measurement influencing the other, and yet there is a correlation (or rather, anti-correlation) between them: when the detectors are set to measure spin along the same axis, they will always measure opposite spins.
According to orthodox quantum mechanics, the particles’ spins become determinate only once the particles interact with the detectors. But this implies that by becoming determinate, one particle’s spin somehow instantaneously (or near-instantaneously)
influences the other particle’s spin. Assuming that this is impossible (i.e. that spatial locality is true), EPR argued that orthodox quantum mechanics must be incomplete. The particles must be emitted with spin values; it’s just that we can’t discover what those are using the calculations currently at our disposal. So in their argument, EPR assume locality and derive the conclusion that quantum mechanics is incomplete.
However, John Bell (1964) showed that locality is in fact inconsistent with orthodox quantum mechanics. He devised an EPR-type test in which either detector could measure spin along a variety of axes. For each pair of particles emitted, the axis that either detector is set to measure along is randomly selected, and done so independently of the other. Given that the axes are randomly selected in this way, the results won’t be perfectly anti- correlated. Sometimes both detectors will measure the same spin, sometimes opposite spins. If we assume locality, and that the particles therefore must have pre-defined spin values as ERP argued, we can calculate the probability of these results. However, as Bell established, these probabilities contradict those calculated using quantum mechanics. Simply, quantum mechanics predicts different results; it predicts results that aren’t possible without nonlocality.
Experiments have since been conducted that confirm the predictions made by quantum mechanics (e.g. Aspect et. al. 1981; Shalm et al. 2015; Hensen et al. 2015), and it is now widely accepted that quantum mechanics demonstrates that interactions between particles in ERP-type cases are nonlocal. So it is indeed possible to formulate and test theories in physics without the assumption of locality – spatial locality, at least. But as it is possible with regards to spatial locality, there’s no obvious reason why it shouldn’t be possible with temporal locality (Adlam 2018).
Let’s allow the A-theorist the point, as far as it can take them: temporal nonlocality is not ruled out. But that of course doesn’t mean it’s true. If the A-theorist is to reject (B3), they will first have to establish that temporal nonlocality is true. This presents a considerable – if not insurmountable – barrier.
The A-theorist might at this point object that the B-theorist is in the same boat. Neither temporal locality nor nonlocality have been established to be true. Temporal locality might be current scientific orthodoxy, but we have seen that it is lacking in justification. So before the B-theorist can claim (B3), they need to come up with a convincing reason for accepting temporal locality.
This is wrong, though. (B3) doesn’t require the truth of temporal locality. This is because temporal locality is sufficient for the truth of (B3), but not necessary for it. (B3) claims that any perceptual awareness of extended events must be derivative if experiential states are momentary: when we are perceptually aware of an event, our experiential states must be causally connected to states of that event, rather than to the event per se. The truth of this claim would be guaranteed by the truth of what we might call the causal connection principle:
CCP: a state can’t be directly causally connected to an event; it can only be connected to a state (or states) of an event.
CCP says, in effect, that states and events can only ever be derivatively connected. In order to resist (B3), the A-theorist must therefore reject CCP. The truth of CCP would, in turn, be guaranteed by the truth of temporal locality.
However, CCP does not require the truth of temporal locality. All CCP requires is that states are only ever non-derivatively connected to other states. Nothing about this precludes the possibility of these state-state connections holding across temporal distances in the absence of intermediaries. In other words, CCP does not rule out the possibility of nonlocal state-state connections. So CCP is consistent with temporal nonlocality. Temporal locality is therefore sufficient but not necessary for CCP. As such, even if – and it’s a big ‘if’ – the A-theorist could establish that temporally nonlocal causal connections are possible, they still wouldn’t have shown that CCP is false.
Moreover, even if the A-theorist could somehow show that CCP is false, they still wouldn’t have shown that (B3) is false. This is because CCP is sufficient but not necessary for (B3). CCP says that states and events can only be derivatively connected. If states can only ever be non-derivatively connected to states (i.e. if CCP is true), then our awareness of events must be derivative if experiences are momentary (i.e. (B3) is true). So (B3) follows from CCP. But even if (B3) is true, and no experiential state can ever be non-derivatively connected to any event qua object of perception, it doesn’t follow that no state can ever be non-derivatively connected to any event. Hence, (B3) is consistent with the falsity of CCP. So even if the A-theorist can somehow show that CCP is false, they still wouldn’t have shown that (B3) is false.
In resisting (B3), the A-theorist is committed against both temporal locality and CCP. However, although the truth of temporal locality and CCP would guarantee the truth of (B3), the B-theorist is committed to neither. Dialectically speaking, the A-theorist has all their work ahead of them just to break even with the B-theorist.