Well, in my humble opinion, the question has its roots in the perceived difficulty in coming to terms with material-immaterial interaction but that's just another way of saying that the two don't/shouldn't interact and that's physicalism in disguise.

If one is a non-physicalist, there's the material body and the immaterial mind, and going by how things are, they do interact. How else does everybody get around?

I maybe a mile off the mark but that's how I fee. — TheMadFool

Maybe the physicalist is humbly asking how opposites interact? If the dualist is going to use terms that are opposites to describe the world, then it is incumbent upon them to explain how they interact. The monist - whether they are a physicalist, idealist, or something else (like me) - doesn't have that problem because they are not using opposite terms to describe the world.

Essentially, the dualists' problem is language-use - using words in antiquated ways that stem from the religious notion that mind can exist apart from the body.

Maybe the physicalist is humbly asking how opposites interact? — Harry Hindu

Why can't opposites interact?

The OP is basically asking how opposites interact. Well MU, how do opposites interact? — Harry Hindu

Have you seen a battery? There's a negative pole and a positive. You put a wire across, and if the battery is strong enough you'll see sparks. That's how opposites interact.

Which is the same as saying that pattern and the substance are one and the same as you can never have one without the other - ontologically. The distinction you are talking about only exists in your mind as language concepts. — Harry Hindu

The pattern, and the substance, are not the same, because the pattern is a mental construct, an abstraction, and the substance is what is independent. We observe the activity and replicate it as "a pattern". But the pattern of waves on water is applicable to other substances, therefore the pattern and the substance are not one and the same. It's the same principle as any property. The property and the substance are not one and the same, because the property is the creation of our sense perception. We see an object as red, but many other objects will be seen as red also. Therefore the property and the substance are not one and the same. The property is a feature of our perception.

However, if we want to allow that the property, or abstraction which is within our mindshas real existence, we need to provide it with a designation of "substance" because substance is what supports the reality of existence. The substance which supports mental things must be different from the substance which supports independent things or else we would have no way to distinguish fact from fiction, as fictions have real (substantial) existence within the mind, but not independent from the mind.

I am now wondering if part of the problem is that dualists seem to think that they see the world as it is (naive realists), and how it appears is different than how it is thought about - hence dualism. You think that the duality exists ontologically, and are unwilling to ponder the possibility that the way it appears in the mind may be different than how it actually is (but that isn't necessarily saying that we can never know about how it actually is). — Harry Hindu

The fact that how the thing appears to the mind is different from how it is independent from the mind is evidence of the reality of dualism. This is because we must account for the existence of both, the appearance, and the independent object. Existence is supported by substance. There is a difference between the independent object and the appearance. The difference cannot be a difference of form because the form of the object is what we come to know, and this would mean we could not know the object because the two forms would be different.. Therefore the difference must be a difference of what underlies, or supports the form, and this is substance.

Pay attention to the bolded part: This can be said about earth, water, fire and air, so why dualism? Your focus on mind and body being special and fundamental would simply be a personal fetish with the two. — Harry Hindu

It's a matter of reduction. There is only a need for two substances to account for the existence of minds and the medium between minds. Being a monist, you have no prerogative for that objection. You want to reduce all to one. The dualist simply points out to the monist, that there needs to be two fundamentally distinct substances, to account for the reality of separation between minds. If you can pull yourself away from your monist assumptions and accept the reality of the need for dual substances, then we can apply the dualist principles and see if a need for other substances arises. So far it has not. But you, insisting on monism are in no place to talk about a possible need for a further multitude of fundamental substances.

You're assuming that there can't be different kinds of one "substance" (again, you haven't even explained what you mean by the word, or what qualifies as a "substance", so until you do, I'm assuming that you don't know what you're actually talking about when you use that word). Just as we have all the different elements that are just different configurations of atoms, we can have different configurations of one "substance". There are different configurations of the same "substance" between the configurations that are our minds. — Harry Hindu

Yes, I agree that there are different configurations of the same substance between our minds. However, within our minds must be a different substance or else there would be no real separation (no real boundary) between our minds. Our minds would interact directly. Hence the need for two distinct substances and no more than two. And if we assume that it is the case that only the different configurations are what have boundaries, then we still need a distinct substance which constitutes those boundaries. Again, we have a need for two distinct substances and no more than two. The need for two distinct substances is unavoidable.