(2) If mind is not spatio-temporal, and body is spatio-temporal, then mind and body cannot interact. — quine

Curious, why not?

This premise seems to rest upon the assumption that something can only be causally relevant to something else in its ontological "space".

If the mental and the physical are indeed two completely different things that have nothing in common at all, it does seem difficult to see how they can interact.

But if the mental and the physical are different, but not entirely, then there is room for them to interact. Say the mental has the property M and the physical has the property P, but both have the property T. By having T, they are able to interact with each other in a way that is not possible to understand from within the ontological "spaces" of those of M or P.

To illustrate, then, say we have the mental: M=====T , and the physical: T=====P. M and P cannot interact directly from the M or P endpoints, but can interact through their T endpoints. Thus just as you cannot understand how a tree obtains nutrients from the ground by only looking at the leaves, we aren't able to understand how the mental and the physical interact from the perspective of the mental or the physical. A holistic picture would be required, but this is exactly what is impossible to obtain directly. Correlationism, basically.

Not saying I necessarily agree to all of this. I'm undecided on what I see to be the most reasonable mind-body interaction theory.

You asked what was the problem for dualism.
I answered.
The problem for dualism is to account for how the non-physical acts upon the physical causally.

The monist does not have this issue because they do not maintain that the non-physical acts upon the physical causally.

What do you mean by asking why it should? — Michael

I mean just what I wrote, why should the non-physical be such that it is causal but not physical?

Because unless the physical is defined as being whatever has causal influence on the physical (a circular and so vacuous definition) then having causal influence on the physical doesn't make you physical (at least not by definition). — Michael

It is not circular or vacuous it is economical.
There is less to account for, if the mind is physical, then that is what accounts for physical causation.
There is no need to multiply explanations beyond monism.

Maybe not if you only consider the interaction problem. But there are other concerns that dualists will claim warrant regarding the mind as non-physical. — Michael

How is dualism necessary?
Are you proposing that monism necessarily false?

I think an implicit issue with these arguments is the weakness of the notion of an 'immaterial substance'. I think it's a self-contradictory notion in most cases, because 'substance' is depicted in a way that is essentially physical, as some kind of stuff or ethereal thing.

There's another way of thinking about 'mind', namely, as 'that which grasps meaning'; the nature of meaning is not something normally associated with the notion of substance. But that is a clue to the nature of mind. When we understand meaning, it can indeed have physical effects; if you receive a credible death threat in writing, then your adrenal glands would kick into action. And there's your interface between mind and body. The mind is constantly engaged in such activities - that is the basis for 'mind-body medicine'.

You could say a lizard will react to danger, and it's adrenals kick into action. That's just physical, isn't it? I would say this instance is matter of stimulus and response. It is characteristic of organisms (but not of inorganic systems). What is different with human cognition is that it can be understood in the abstract, in terms of meaning, and the relationship of ideas, rather than between cognition and reaction. That ability to perceive meaning in terms of the relationship between ideas is what constitutes res cogitans.

http://www.newyorker.com/books/page-turner/thomas-nagel-thoughts-are-real

Where is there meaning without syntax though?

If meaning is just syntax then there is no reason it can not be physical.

I don't see any reason to believe (2). Also, the mind is temporal.

There is no 'interaction problem.' As Hume noted, even the problem of motion of bodies in different points of space is rationally inexplicable. There is a 'motion problem' just as much as there is an 'interaction problem.'

Where is there meaning without syntax though? — m-theory

Meaning is a question of semantics not syntax although the two are interdependent. Searle and others all go into that.

That is where we disagree.
I do not view syntax and semantics as interdependent.
You acknowledge yourself that there are examples where there is no meaning to account for the behavior of the lizard.
Syntax is not dependent upon semantics but semantics is dependent upon syntax.

Semantics- Grammatical rules for assigning meaning to a sentence.
Syntax- Grammatical rules for specifying correct word order and inflectional structure in a sentence.

Accordingly, semantics relies on the ability to grasp meaning, which is an attribute of rational and linguistic ability. Syntax only requires grasp of grammar, whereas semantics requires knowledge. You could compose any number of syntactically-correct statements which mean nothing; happens here frequently. ;-)

But, that is a tangent to the OP so perhaps we ought to adjourn.

I agree with you if we are talking generally, but people (in my experience, usually dualists) try to use their viewpoint on the mind to defend a viewpoint on something that matters (free will or the existence of non-physical objects). It usually is not argued for intially, but is a careover or a requirment for another belief. — Chany

It would be nice to know in what sense the non-computable numbers and similar entities exist.

Also, even in the case of a computer, where exactly does the computation take place?

There is no 'interaction problem.' As Hume noted, even the problem of motion of bodies in different points of space is rationally inexplicable. There is a 'motion problem' just as much as there is an 'interaction problem.' — The Great Whatever

You don't happen to have a reference for that do you?

Anyway, it's perhaps a little too much to expect anyone from the 1700s to anticipate modern science.

I can't see how that could work.

The assumption is that causes and effects occur in space and time. Descartes defines minds as not being located in space and time. According to Descartes' definition of mind, minds can't be causes or effects. Interactions imply causation. So, Descartes' definition is wrong. In order to explain mind-body interaction, minds must be located in space and time. If minds are located in space and time, then Descartes' definition of mind is false, and dualism is false, too.

Descartes' solution is also false. Pineal glands themselves are extended in space and time. Minds that are not extended in space and time cannot be moderated by pineal glands that are extended in space and time.

The assumption is that causes and effects occur in space and time. — quine

The trouble with that is, 'causes and effects' only operate given certain constraints and conditions. Why atoms and molecules have the properties they do, is wholly dependent on a chain of causation, which somehow appears to point back to the origin of the Universe, or, alternatively, are simply 'thus'. So, the nature of those particular kinds of questions, are metaphysical, i.e. about what must obtain if there is to be physics in the first place.

Aristotle, and the scholastic tradition, and Thomas Aquinas, understood those kinds of questions and proposed various doctrines as a consequence. Descartes wished to throw off scholasticism and Aristoteleanism and instead proposed his 'new philosophy' of substance dualism. However it was at least an attempt at a metaphysic. Whereas to say that causes and effects occur solely in space and time, is to assume that nature, as it were, contains its own cause, ground, or reason for existence. Or, to put it another way, that the only kinds of causes are material and efficient causes, the kinds of causes that can be understood in terms of a temporal sequence of events, a physical causal chain.

A simplistic illustration of all of that is that numbers, for example, or logical laws, are not themselves 'in space and time'. The law of identity will hold here, on Andromeda, or on some other world-system, because in order for anything to exist, there have to be such kinds of constraints that we describe in terms such as the law of identity. And the mind is able to grasp such laws, becuase of its rational nature. So, according to traditional philosophy, the rational mind is able to grasp the rational order of things, which is an attribute of the fabric of the cosmos, and are the necessary condition for there to BE space and time.

You're preaching basic scientism.

The assumption is that causes and effects occur in space and time. — quine

And your assumption is one that Descartes denied, being that he claimed that the mind doesn't "occur in space" but is nonetheless a cause.

The assumption is that causes and effects occur in space and time. Descartes defines minds as not being located in space and time. According to Descartes' definition of mind, minds can't be causes or effects. Interactions imply causation. So, Descartes' definition is wrong. In order to explain mind-body interaction, minds must be located in space and time. If minds are located in space and time, then Descartes' definition of mind is false, and dualism is false, too. — quine

I don't think you need to make any assumptions, or appeal to cause and effect. According to our knowledge there are only 4 forces that describe all interactions. If there were a 5th force, then this would necessarily be in physical reality, so Dualists would then require a 6th etc.

However, when a computer is playing you at chess (or Go or poker) where exactly is the chess program? The program being of course an abstract algorithm to achieve an abstract outcome based on an abstract set of rules.

Nothing that Hume said on the issue has ever been addressed seriously, as far as I'm aware.

For that matter, neither has anything Descartes said. For all the sentiment against interactionist dualism, I've never heard a solid argument against it, and if you scan this thread, you will also not find (even the beginning of) one.

However, when a computer is playing you at chess (or Go or poker) where exactly is the chess program? — tom

The "chess program" is our abstraction of the mechanical events occurring inside the computer.

Consider: the question of how something material and something non-material can possibly interact seems to presuppose that it is clear how two material things interact. But why can we not equally ask, how is it that two separate things in space, apart from one another, come into interaction?

If you say, because we define causality that way, then this is not good enough, for then we can just defined causality so as to include interaction between the mental and physical, seeing as we seem to have so many obvious instances of it, and you beg the question.

If you say, we don't know how, but we can observe this happening and write down generalizations as to how it does, then this is not good enough, because then we can do the same with physical and mental activity, the correlations between which are even pre-theoretically obvious and abundant.

So what is the argument? In what way is the interaction between the mental and physical mysterious, that interaction between physical objects already is not? What provision can you make for one that will not carry over to the other?

Consider: the question of how something material and something non-material can possibly interact seems to presuppose that it is clear how two material things interact. But why can we not equally ask, how is it that two separate things in space, apart from one another, come into interaction? — The Great Whatever

The interaction is by what we call forces. Three of them are by particle exchange, two of which only operate on the sub-atomic scale. The fourth interaction is arguably not a force, but an effect of space-time geometry.

If you say, because we define causality that way, then this is not good enough, for then we can just defined causality so as to include interaction between the mental and physical, seeing as we seem to have so many obvious instances of it, and you beg the question. — The Great Whatever

Physics does not define causality. Our fundamental laws are time-symmetric, so they can't include any conception like causality.

Once you define causality to include the interaction between the mental and physical, then what are you going to do apart from stare at a definition?

The "chess program" is our abstraction of the mechanical events occurring inside the computer. — Michael

Is the computer playing chess or not? If so, how?

Is the computer playing chess or not? If so, how? — tom

Yes. But the "computer playing chess" is our abstraction of the mechanical events occurring inside the computer. So are you asking how the mechanical events occur? Or how we come to form such an abstraction?

I'm struggling to see what relevance this post has to the question.

Yes. But the "computer playing chess" is our abstraction of the mechanical events occurring inside the computer. — Michael

If a computer is controlling a power station or a refinery, is that "controlling a power station" our abstraction or is it really controlling a power station?

If a computer is controlling a power station or a refinery, is that "controlling a power station" our abstraction or is it really controlling a power station? — tom

That depends on whether by "really controlling a power station" you mean it in an abstract sense like "playing chess" or if you mean it in a more concrete sense like "it is mechanically responsible for the mechanical behaviour of the power station".

So to save me from having to answer 101 questions, whenever you ask a question like "when a computer is doing X, where exactly is the X?", either the X is some mechanical process (and so has a location) or it's our abstraction of this mechanical process.

The assumption is that causes and effects occur in space and time. Descartes defines minds as not being located in space and time. According to Descartes' definition of mind, minds can't be causes or effects. Interactions imply causation. So, Descartes' definition is wrong. In order to explain mind-body interaction, minds must be located in space and time. If minds are located in space and time, then Descartes' definition of mind is false, and dualism is false, too. — quine

You put the problem right there in the first sentence. You assume (hold to be true for no reason) that causality can only occur in space-time, which can be argued against not only by mind-body dualists, but by anyone who has any conception of something beyond the physical (or even a conception of the physical that goes beyond space-time). So, I guess theism is assumed out the window.

Descartes' solution is also false. Pineal glands themselves are extended in space and time. Minds that are not extended in space and time cannot be moderated by pineal glands that are extended in space and time. — quine

Descartes is publishing around the mid-1600s. I think attacking the whole pineal gland thing is pointless.

What do you mean by asking why it should . . . — Michael

The problem is that there's no non-physical account of how anything is supposed to work.

The problem is that there's no non-physical account of how anything is supposed to work. — Terrapin Station

Quite, but perhaps it might be more accurate to say that there are no good non-physical accounts. By "good" I mean an account that is difficult to modify and still account for the explicanda.

e.g. The mind interacts with physical reality via pre-established harmony, or angels, of rays that only conscious brains can detect, etc.

The hard problem is precisely hard because of the rigorous demands physicalism imposes on its explanations.

Dualists seem happy to state at a word re-definition and think they have achieved something.

I don't think it fair to say that dualism fails because it hasn't explained how the mind and the body interact. There are a lot of things that physics hasn't explained (which is why we don't have a theory of everything) but it doesn't then follow that it's fair to say that physicalism fails for this reason. — Michael

Speaking as a physics layman, my understanding is that theorists have been struggling to reconcile QM and relativity, as the theories work well in their own domains, but break down into nonsense when one attempts to integrate the theories (something about crazy infinities popping up all over the place, I think). Given this failure of reconciliation, would it not follow that at least one of theories (QM or relativity) are false (not that something like those theories couldn't be true)?

Translating this analogy to the thesis of substance dualism, the substance dualist (qua substance dualist) would likely assent to three core propositions:

(1) the mind is res cogitans.
(2) the body is res extensa.
(3) mind and body interact.

Of these three propositions (3) would seem to be on the most secure footing, and is therefore the least likely to be false. So, assuming that the substance dualist cannot dismiss mind/body interaction, and cannot reconcile the interaction problem, does it not follow (in the manner of QM and GR's reconciliatory failure) that (1) and/or (2) must be rejected? And if either (1) or (2) are false, then substance dualism is false.

That would be an argument from ignorance.

True. Historically, one of the more annoying responses to empirical demonstrations of some phenomenon is to dismiss it for want of a mechanism (e.g. plate tectonics). However, scientific theories can always be fleshed out by empirical observation and collecting more data. The same is not true of metaphysical theses, which only require thinking one's way to a solution. If, after a few hundred years of substance dualism, no one has yet posited a convincing resolution of the interaction problem, does that justify at least diminished confidence that substance dualism is the correct metaphysical theory of mind?

If, after a few hundred years of substance dualism, no one has yet posited a convincing resolution of the interaction problem, does that justify at least diminished confidence that substance dualism is the correct metaphysical theory of mind? — Arkady

I don't think so. As I said, the interaction problem is not the only problem. Dualists are dualists because they believe that there are problems that a physicalist account of consciousness cannot resolve. That a physicalist account of consciousness can resolve the interaction problem by avoiding it entirely doesn't help it avoid the problems that dualists claim it does have.

Speaking as a physics layman, my understanding is that theorists have been struggling to reconcile QM and relativity, as the theories work well in their own domains, but break down into nonsense when one attempts to integrate the theories (something about crazy infinities popping up all over the place, I think). Given this failure of reconciliation, would it not follow that at least one of theories (QM or relativity) are false (not that something like those theories couldn't be true)?

Translating this analogy to the thesis of substance dualism, the substance dualist (qua substance dualist) would likely assent to three core propositions:

(1) the mind is res cogitans.
(2) the body is res extensa.
(3) mind and body interact.

Of these three propositions (3) would seem to be on the most secure footing, and is therefore the least likely to be false. So, assuming that the substance dualist cannot dismiss mind/body interaction, and cannot reconcile the interaction problem, does it not follow (in the manner of QM and GR's reconciliatory failure) that (1) and/or (2) must be rejected? And if their (1) or (1) are false, then substance dualism is false.

I think the difference between the two situations is that QM and relativity are inconsistent, and so one must be false, whereas the interaction problem is simply a mystery. It's not the case (at least according to the dualist) that res cogitans and res extensa interacting leads to contradictory consequences.