Last Sunday while on a longer bike ride, it occurred to me that gravity, electromagnetism, and the two nuclear forces (or whatever force winds up being posited by the Theory of Everything to supplant them), are examples of non-physical things that operate on physical objects. This is significant because it counters thinkers who object to interactionist dualism (a view I happen to hold, and for more reasons than just the Ice Cream Argument) by claiming that something non-physical cannot operate causally on something physical.
So a naive objection to dualism might be made by someone who thinks up instances of things causing effects in other things by means of purely physical mechanisms. Billiard balls and dominoes smack into each other and knock each around, tires rub against asphalt and move cyclists forward, propellers churn through water and generate momentum, etc. In light of these cases, one might argue, it seems like causation occurs by physical interactions between physical objects (setting aside Humean objections for a second). Assuming non-physical entities like minds could even exist, what would it even look like for them to be able to act causally on physical brains?
I have my opinions about the models for mind-brain interactions that are out there, and maybe I’ll get around to talking about them someday. But in the meantime, to make it seem less weird, it might help to think about gravity. Because of gravity, physical bodies like planets act causally on one another without touching physically. And this even occurs across billions of lightyears of empty space.
Kinda freaky, right?
In fact, it turns out that all causality is this way. The only reason billiard balls ricochet off one another is electromagnetism. If you could zoom way in and observe a billiard ball collision extremely loud and incredibly close (shout out), according to particle physics, you wouldn’t see solid masses striking each other. You would see spheres suspended in space do-si-doing around one another in patterns that, at some distance, make up large spherical clouds. These clouds could easily pass through each other if it weren’t for some invisible force that, when they got close to one another, drove them apart: electromagnetism.
It’s the only reason I’m not drug though the floor into the center of the earth. Gravity is strong but electromagnetism is stronger.
These four fundamental forces are all “non-contact” forces. All of them. The fundamental ones.
So maybe it isn’t too weird to think about causality non-physically, since, well, even the most “physical” examples of causality we can think of like billiard balls and dominoes, are non-physical anyway.
I admit that, in the case of the fantastic four forces, we are not necessarily talking about non-physical entities, but about interactions between physical entities, whereas in the case of the mind, we are talking about a non-physical entity interacting with a physical one. But maybe stopping to remember that causal interactions themselves are all non-physical to begin with can encourage skeptical layman to consider the possibility of souls a little more open-mindedly. After all, these how-type objections to dualism only concern the possibility of interaction to begin with (not the possibility of the existence of non-physical objects). So granting me, for the sake of argument, that there may be non-physical objects like minds, why wouldn’t they be able to interact causally with physical objects?