A bit of finetuning

Here’s a bit of finetuning in the world’s laws that I just noticed. All the four fundamental forces of nature are conveniently local, in the sense that they drop off to nearly zero with distance. If any one of them weren’t local, the world would not be likely to be predictable to limited knowers like us.

Force-realism and simultaneous causation

If a charged particle is an electromagnetic field, the field exerts a Lorentz force F = qE + qv × B, where q and v are the charge and velocity of the particle, E is the electric field and B is the magnetic field. All of these quantities are taken at one location in spacetime. Thus, if realism about forces is correct, we have simultaneous causation: the electromagnetic field simultaneously causes the force.

Not everyone is a realist about forces, though. One might think that the electromagnetic field directly causes the subsequent change in velocity instead of causing a force which in turn causes the change in velocity.

Forcing and threatening

Suppose the state thought it had good reason to force me to undergo a medical procedure that I believed to be immoral. The state would have two kinds of options:

1. Threaten me with a variety of serious threats such as deprivation of employment and educational opportunities, fines or imprisonment if I refused to cooperate with the procedure.

2. Force me to undergo the procedure by physically holding me down and performing the procedure.

Intuitively, the threat option seems like the “nicer” option, at least if the threats fall short of imprisonment. And the force option clearly violates standard principles of consent in medical ethics.

But what has struck me was this interesting fact: depending on the details of the case, I might well prefer being forced to being threatened. For if I am threatened, there are two possibilities: either I resist the threat or I give in. If I resist, then I have to suffer the serious losses that were threatened. And if I give in, then I have to live with the knowledge that I have violated my conscience. But if I am forced, then my conscience is clear, I do not suffer any of the threatened losses, and if the procedure is one that is in fact medically beneficial, I get the benefits of the procedure. (And note that it is quite possible to believe a procedure to be immoral while knowing that it is medically beneficial. For instance, one might reasonably think that it is immoral to accept an organ transplant from a prisoner who was compelled by an evil state to yield the organ, even though one knows that the transplant would be beneficial.)

Of course, if asked, I couldn’t very well say: “Please force me.” For that would be consent to a procedure I believed to be immoral. But nonetheless I might prefer the force option. In such a case, it’s hard to say that the threat option is “nicer”. Indeed, it might impose much greater hardship than the force option.

So from the point of view of a state that thinks the procedure is intrinsically permissible and necessary for the public good, it seems that there is good reason to prefer the force option, in that it might impose much less hardship. But this seems paradoxical. It seems obvious that the threat option is better, especially for non-punitive threats that are “naturally” tied to the refusal (“We won’t employ anyone who medically could be vaccinated but refuses to be”), even though the force option seems the better one for both the person being forced and for the rest of society (since it’s more effective).

Perhaps the way out of the paradox is that it is so important for us as a society to maintain the requirement of consent for medical procedures that forcing people to undergo a medical procedure should be avoided except in the most extreme of cases (such as when the very existence of society is at stake), and hence even though the short-term consequences of forcing are better than those of threatening—including morally better for the person being forced who isn’t tempted to violate conscience—forcing should be avoided. But this isn’t a complete solution. For normally we think threats also vitiate consent. But perhaps they vitiate it less?

Instantaneous Newtonian gravitational causation at a distance?

It’s widely thought that Newtonian gravity, when causally interpreted, involves instantaneous causation at a distance. But I think this is technically not right.

Suppose we have two masses m₁ and m₂ with distance r apart at time t₁. The location of m₂ at t₁ causes m₁ to accelerate at t₁ towards m₂ of magnitude Gm₂/r². And this sure looks like instantaneous causation at a distance.

But this isn’t an instance of instantaneous causation. For facts about what m₁’s acceleration is at t₁ are not facts about how the mass is instantaneously at t₁, but facts about how the mass is at t₁ and at times shortly before and after t₁: acceleration is the rate of change of velocity over time. Suppose that a poison ingested at t₁ caused Smith to be dead at all subsequent times. That wouldn’t be a case of instantaneous causation, even though we could say: “The poison caused t₁ to be the last moment of Smith’s life.” For the statement that t₁ is the last moment of Smith’s life isn’t a statement about what the world is instantaneously like at t₁, but is a conjunctive statement that at t₁ he’s alive (that part isn’t caused by the poison) and that at times after t₁ he’s dead (that part is caused by the poison, but not instantaneously). Similarly, m₁’s velocity (and position) at times after t₁ is caused by m₂’s location at t₁, but m₁’s velocity (or position) at t₁ itself is inot.

Let’s call cases where a cause at t₁ causes an effect at interval of times starting at, but not including, t₁ a case of almost instantaneous causation. In the gravitational case, what I have described so far is only almost instantaneous causation. Of course, people balking at instantaneous action at a distance are apt to balk at almost instantaneous action at a distance, but the two are different.

The above is pretty much the whole story about instantaneous Newtonian causation if one is not a realist about forces. But if one is a realist about forces, then things will be a bit more complicated. For m₂’s location at t₁ causes a force on m₁ at t₁, which complicates the causal story. On the bare story above, we had m₂’s location causing an acceleration of m₁. When we add realism about forces, we have an intermediate step: m₂’s location causes a force on m₁, which force then causes an acceleration of m₁. (There might even be further complications depending on the details of the realism about forces: we may have component forces causing a net force.) Now, when the force-at-t₁ causes an acceleration-at-t₁, this is, for the reasons given above, a case of almost instantaneous causation. But the causing of the force-at-t₁ by the location-at-t₁ of m₂ is a case of genuinely instantaneous causation.

But is it a case of causation at a distance? It seems to be: after all, the best candidate for where the force on m₁ is located is that it is located where m₁ is, namely at distance r from m₂. (There are two less plausible candidates: the force acting on m₁ is located at m₂, and almost instantaneously pulls on m₁; or it’s bilocated between the two locations; in any case, those candidates won’t improve the case for instantaneous action at a distance.) But here is another problem. The force on m₁ is not produced by m₂. It is produced by m₁ and m₂ together. After all, the Newtonian force law is Gm₁m₂/r². (It is only when we divide the force by m₁ to get the acceleration that m₁ disappears.) Rather than m₂ pulling on m₁, we have m₁ and m₂ pulling each other together. Thus, m₂ instantaneously partially causes the force on m₁ at a distance. But the full causation, where m₁ and m₂ cause the force on m₁, is not causation at a distance, because m₂ is at the location of that force.

In summary, the common thought that Newtonian gravitation involves instantaneous causation at a distance is wrong:

• If forces are admitted as genuine causal intermediates (“realism about forces”), then we have almost instantaneous causation of acceleration by force (moreover, not at a distance), and instantaneous partial causation of force at a distance.

• Absent force realism, we have almost instantaneous causation at a distance.