@RexKerr, given what you have said, I'm not sure what would falsify the causal closure of physicalism. Any violation of causal closure can be eliminated by subsuming whatever it is that violates causal closure. Alternatively, we can just stop looking for causes (e.g. of quantum fluctuations), and declare that causal closure holds.

What seems to be the case is that physicalism actually cannot be falsified unless we find that something like Cartesian dualism holds, and even that is problematic, given the problems of interaction, which threaten to collapse the dualism into a monism, or render the non-physical aspect of dualism irrelevant.

The only option left seems to be god-of-the-gaps, which is undesirable theologically, philosophically, and scientifically.

This gets very close to physicalism being unfalsifiable, denying nothing of interest, and therefore being meaningless. Randal Rauser's Not even wrong: The many problems with Naturalism may be of interest, here.

@labreuer - If you take physicalism to mean "no injection of information", then it's very easily falsifiable. For instance, if you find correlated decays of particles, then it looks like you've got either injection or there is some unknown physical causal factor that correlates particle decays. Physicalism looks less certain.

The weirdest thing I'm aware of in this regard is QM states that are correlated across large distances. If we allow for injection of entropy (without information, because it's not correlated with anything pre-existing) then this is a bit puzzling.

But not outright a contradiction of physicalism.

I don't think we should hold against physicalism how successful it is.

If things like the divine right of kings, that God wouldn't allow a guilty party to be killed in a duel, that there was a universal consciousness to tap into, etc., then physicalism would be a poor model.

But although those things were postulated, they didn't turn out to be true.

@RexKerr, how do your examples not all fall in the category of "god-of-the-gaps"? I don't even see how this "universal consciousness to tap into" would violate physicalism; you'd still have the interaction problem of Cartesian dualism that threatens to collapse dualism into monism.

In a class on quantum decoherence theory, the professor talked about a complete description of reality being akin to the tensor product of our observable Hilbert space with another, unobservable Hilbert space.

But even that might be viewable as the "hidden information" that is entropy; see Why is information indestructable?.

Suppose there is "injection of information". How would we know it? What would the discovery that the new information is coming from "outside" look like? I wonder if new information can come via the cloning of black hole complementarity, plus Hawking radiation. It's not clear this would falsify physicalism. Why not just subsume the thing that is generating information?

@labreuer - A clear signature of information injection is the detection of highly complex patterns without mechanism to causally relate them.

If your point is that there is always some wiggle room, yes, I agree--such is often the case with almost any empirical result about a theory that isn't incredibly simple.

But pragmatically you pretty quickly abandon physicalism as currently conceived if you see these things, and stick physicalism in the evil demon category--formally possible, but useless in practice.

@RexKerr, I can't help but seeing "highly complex patterns without mechanism to causally relate them" as god-of-the-gaps. Am I incorrect in doing so?

Furthermore, there are questions about human cognition to be asked. How can we even know that such patterns exist? Suppose we look at the fine-tuning argument. One could call that a "highly complex pattern without mechanism to causally [explain it]", but we are quite ignorant about what generated the constants, and so we don't know how probable it was that life-supporting constants 'happened'.

It strikes me that the physicalist always has an out: "We don't yet understand how that complex pattern emerged, but we hope to at some point, such that causal closure is maintained." And it's not clear that the other position—that gaps prove violation of causal closure—has any validity. For example, is it anything other than the setting up of a wall, impervious to future investigation?

@labreuer - All explanatory theories are vulnerable to being overturned or at least heavily modified by gaps in their explanatory power. The god-of-the-gaps is different; it fills in every gap you've got and then you throw it away once you understand what is actually going on.

Since these are all empirical matters, you ought not set up any walls. Rather, you say: well, physicalism is really not working out so well here, so sure, we can keep trying for physical explanations but we should tentatively reject it as universally true.

Or: it's been working so well that we should tentatively accept it as universally true (i.e. a very good model) but we should keep our eyes open in these spots where not everything is nailed down yet and therefore there is a possibility that we'll recognize that we're wrong.

I agree that finding patterns is a hard thing to do, and that fine-tuning arguments don't cut it. You need routine injection of information to be able to spot it. I'm not sure how meaningful physicalism is as a theory of universe-generation.

Instead, it's on much more solid footing when talking about what we've got now and how it behaves, and that's where it's done particularly well.

I do not understand how science could be done after the rejection of physicalism, other than to only operate inside regimes in which causal closure obtains. You understand how important conservation laws are to ability to model systems, right?

@labreuer - You probably couldn't do science very well--you'd do it more like social science--in regimes where causal closure was routinely violated. Conservation laws are great when you can get them, but are not absolutely required. (Biology, for instance, makes pretty good headway without relying on conservation laws in any immediate sense.)

@RexKerr, An interesting thing about social science is that it deals with minds, which so far are able to escape comprehensive modeling thereof.