What would an immaterial cause look like?
That is, by which criteria will we decide that a cause of some effect in the physical causal network is immaterial?
Since science works by detecting effects, and then inferring causes, how would science distinguish a material from an immaterial cause?
My guess: there is no way. Science isn’t about ‘material’ causes, but about causes. Put another way, science isn’t about the ‘physical’ world, but about prediction. If there is some cause, but it isn’t predictable, will it be classified as immaterial? No – science will simply focus on how to make predictions about its unpredictability.
Consider the following passage by Edward Feser, where he is discussing the “Mechanical Philosophy” prominent in early science (The Last Superstition, 2008, p. 179):
“The original idea was that the interactions between particles were as “mechanical” as the interactions of the parts of a clock, everything being reducible to one thing literally pushing against another. That didn’t last long, for it is simply impossible to explain everything that happens in the material world on such a crude model, and as Newton’s theory of gravitation, Maxwell’s theory of electromagnetism, and quantum mechanics all show, physical science has only moved further and further away from this original understanding of what “mechanism” amounts to. [… T]here is by now really nothing more left to the idea of a “mechanical” picture of the world than the mere denial of Aristotelian final causes[.]”
That is, things that wouldn’t have been considered ‘material’ in the past are now routinely thought of as so – as paradigms of material processes. The reason is that science is opportunistic – it finds effects, and tries to create models that explain them. If there are causes, traditionally understood as ‘immaterial’, then in the limit science will have to account for them, and will not think it is describing something immaterial in doing so.
Consider this from Daniel Dennett (Freedom Evolves, 2003, p. 1):
“One widespread tradition has it that we human beings are responsible agents, captains of our fate, because what we really are are souls, immaterial and immortal clumps of Godstuff that inhabit and control our material bodies […] But this idea of immaterial souls, capable of defying the laws of physics, has outlived its credibility thanks to the advance of the natural sciences.”
So, how would we tell that there are immaterial causes to our material behaviour? There wouldn’t be a sign blazing down from the sky saying ‘that was an immaterial cause – physics defied!’ Rather, we would have effects in the brain (say), and we would then infer causes. “There’s something there, causing these effects.” We would then develop a model of what that thing is. It would then come under the rubric of the physical sciences.
That is, natural science says there aren’t immaterial causes, but that’s because science rules out the possibility of an immaterial cause on conceptual grounds – to be in natural science is to effect the physical world, and to effect the physical world is to be physical.