"We may regard the present state of the universe as the effect of its past and the cause of its future. An intellect which at a certain moment would know all forces that set nature in motion, and all positions of all items of which nature is composed, if this intellect were also vast enough to submit these data to analysis, it would embrace in a single formula the movements of the greatest bodies of the universe and those of the tiniest atom; for such an intellect nothing would be uncertain and the future just like the past would be present before its eyes." -- Laplace
My understanding is that Laplace's demon was primarily intended as a heuristic for understanding microphysical determinism. But there is a serious question (noted by or implicit in the work of a number of philosophers of science, e.g., Sober, Loewer, Albert) as to whether, in fact, "nothing" about the physical universe would escape the demon's knowledge. There is some ambiguity in what is meant by "submit these data to analysis," but intuitively it seems that the demon's abilities would only allow him to know all of the facts describable in microphysical terms. There is a real question then about whether this would amount to knowledge of all of the facts, including about mereologically composite objects, let alone about minds.
Would we need to add to the demon's capacities, then, some sort of additional "translation manual" to tell him which macro-states are being realized by the micro-physical states? And would this amount to a problem for a reductionist picture of the world? Maybe, maybe not.
Showing posts with label physicalism. Show all posts
Showing posts with label physicalism. Show all posts
Wednesday, April 26, 2017
Sunday, November 16, 2014
Lowe, Mental Causation and Laws of Nature
E.J. Lowe has an interesting theory of dualistic mental causation. He proposes a model where mental causation doesn't happen by mental events directly causing particular physical events. Instead the mental exerts its influence by explaining the existence of the entire neural causal chain leading to physical movement.
Suppose you have a series S of neural events in the actual world which lead to a physical movement P. Given Lowe's view that the mind does not directly cause any neural event there must be an external physical event E which causes the first event in the neural chain. So it'll look something like this:
Suppose Lowe is right and mental events do not directly cause any particular neural event, but instead explain why this whole series of neural events exists instead of another. For comparison, Lowe proposes that the mind acts in the same way that God could act as sustainer of the universe. Suppose the universe is an infinite series of physical events where God doesn't directly cause any of the events in the series:
Now, every event in the series has a physical cause within the series, but there is still the question about why it is U which exists in the first place as opposed to another, distinct, series (say U*):
On this picture God does not directly cause any particular physical event in U, but rather explains why this whole series of physical events exists in the first place. Here God sustains the universe, as opposed to interacting with it.
If the mind's influence on the body is like this, then the mind would have to have counterfactual control over which series of events occurs given E. In other words, if the mind had decided differently, then had E happened a different chain of neural events would have existed than S.
Now presumably one chain of events is identical to another if all the events in the one chain are identical to the corresponding events in the other. Somewhat more precisely:
Obviously an identity criterion for infinite causal chains would be pretty easy to give too, but we're dealing with causal chains in the brain which lead to physical movement, so presumably this is unnecessary for our purposes. If you like you can think of this criterion as being restricted to causal chains in the brain.
Now then, suppose the mind does cause a different chain than the actual one. Call this chain S*. In order for a different causal chain to happen than the actual one it'd have to look something like this (for convenience I put the original chain above the new one):
The reason there must exist an i such that Ni =/= Ni* is because of our identity criterion above. If all the corresponding events in the chains are identical then the chains themselves are identical. But we supposed that some different chain was brought about, which again is possible given Lowe's view, since Lowe's view implies the mind has counterfactual control over which series of events occurs given E.
I leave blanks in between E and N1* and between Nm* and P since we don't want to assume too much; maybe the mind will cause a chain to exist which is uncaused or which does not lead to the same physical movement P. Now, there are a few possibilities here.
(i) If E does not cause N1* then a law of nature is violated, since (in the actual world) it is a law that E will cause N1. (Actually, if I were being more precise a bit more detail and argument would be necessary here, but this is right.)
(ii) If E does cause N1* and N1 =/= N1* then a law of nature is violated, since it is a law that E will cause N1. Moreover, the laws of nature are changed, since E causes something else than it normally would.
(iii) If E does cause N1* and N1 = N1* then no law of nature is violated yet, and we must look for the smallest i in the chain such that Ni =/= Ni*.
(iv) Again, such an i exists because of our identity criterion and the assumption of a different series S*. So Ni =/= Ni*. Then it will follow that Ni-1 = Ni-1*. So Ni-1 does not cause Ni. So a law of nature is violated, since it is a law that Ni-l will cause Ni.
Moreover, Ni-1 must cause Ni*, since this is a chain of neural events leading to a physical movement. By a metaphysically motivated syntactic rule for these representations of causal chains, there must be a '>' between every node in the chain. (If there were causal 'gaps' how could you really call it a causal chain; the only real causal chains would be the ones before and after the 'gap'.) So that means a law of nature is changed, since Ni-1 causes something different than it normally would.
So, no matter what, if the mind ever exercises the power it has to bring about another neural causal series, a law of nature must be violated. Moreover, if the first event in this series is caused then the laws of nature must be changed by the mind at some point. This is bad.
However, there's more to say than just that it's bad. Lowe could reply that, in the actual world, there are psychophysical laws which hold and which tell us the mind never actually uses this power of counterfactual control over laws. Thus, the normal patterns of events we observe still obey the laws of nature. The laws of nature continue to hold in this world.
But that leaves two options: (1) Does that mean minds never actually do anything? Are they causally effete and just let the world stay its course? Or else (2) Do minds still do something, and thereby contribute some causal influence? If they do, does that mean they cause the actual laws of nature to hold in the case of neural causal chains?
Both possibilities seem weird and unpalatable. If the first view is true that means mental causation never actually occurs in this world, though it could. On the second view there are two possibilities: Either (A) mental causation is superfluous, or else (B) laws of nature are really really weird.
On the one hand, it could be that the laws of nature by themselves are enough to explain why each event in the series causes the next, in which case the mental decision is superfluous and just 'backs up' the law of nature by its influence. The mind gives the laws of nature more 'oomph', though they are completely sufficient even without this 'oomph' at all. This would be case (A).
On the other hand, it could be that, once we move from E to N1, all of a sudden the mind is needed to hold up the laws of nature from then on. This is option (B). And that seems weird. That would mean when the brain comes into play, all of a sudden the laws of nature by themselves aren't sufficient for producing later events and the influence of the mind is needed to 'keep them going'. When it comes to the brain, the laws of nature need crutches; the mind is a metaphysical crutch. This is very metaphorical of course, but the point could certainly be made more precisely.
To be fair, this theory can't be disproven by the science. Neither option (1) nor (2) above is even possibly ruled out by the actual scientific evidence. So maybe this is one way to reject causal completeness while holding a theory that is empirically equivalent. I'm not sure it's a plausible one though.
Suppose you have a series S of neural events in the actual world which lead to a physical movement P. Given Lowe's view that the mind does not directly cause any neural event there must be an external physical event E which causes the first event in the neural chain. So it'll look something like this:
- S: E > (N1 > N2 > ... > Nn) > P
Suppose Lowe is right and mental events do not directly cause any particular neural event, but instead explain why this whole series of neural events exists instead of another. For comparison, Lowe proposes that the mind acts in the same way that God could act as sustainer of the universe. Suppose the universe is an infinite series of physical events where God doesn't directly cause any of the events in the series:
- U: ... > P0 > P1 > P2 > ...
Now, every event in the series has a physical cause within the series, but there is still the question about why it is U which exists in the first place as opposed to another, distinct, series (say U*):
- U*: ... > P0* > P1* > P2* > ...
On this picture God does not directly cause any particular physical event in U, but rather explains why this whole series of physical events exists in the first place. Here God sustains the universe, as opposed to interacting with it.
If the mind's influence on the body is like this, then the mind would have to have counterfactual control over which series of events occurs given E. In other words, if the mind had decided differently, then had E happened a different chain of neural events would have existed than S.
Now presumably one chain of events is identical to another if all the events in the one chain are identical to the corresponding events in the other. Somewhat more precisely:
- (E1 > E2 > ... > Em) = (E1* > E2* > ... > Em*) if and only if (a) E1 = E1* and E2 = E2* and ... and Em = Em*; and (b) Ei > Ei+1 if and only if Ei* > Ei+1* for 1 < i < m
Obviously an identity criterion for infinite causal chains would be pretty easy to give too, but we're dealing with causal chains in the brain which lead to physical movement, so presumably this is unnecessary for our purposes. If you like you can think of this criterion as being restricted to causal chains in the brain.
Now then, suppose the mind does cause a different chain than the actual one. Call this chain S*. In order for a different causal chain to happen than the actual one it'd have to look something like this (for convenience I put the original chain above the new one):
- S: E > (N1 > N2 > ... > Nn) > P
- S*: E _ (N1* > N2* > ... > Nm*) _ P with Ni =/= Ni* for some i, 1≤ i ≤ n
The reason there must exist an i such that Ni =/= Ni* is because of our identity criterion above. If all the corresponding events in the chains are identical then the chains themselves are identical. But we supposed that some different chain was brought about, which again is possible given Lowe's view, since Lowe's view implies the mind has counterfactual control over which series of events occurs given E.
I leave blanks in between E and N1* and between Nm* and P since we don't want to assume too much; maybe the mind will cause a chain to exist which is uncaused or which does not lead to the same physical movement P. Now, there are a few possibilities here.
(i) If E does not cause N1* then a law of nature is violated, since (in the actual world) it is a law that E will cause N1. (Actually, if I were being more precise a bit more detail and argument would be necessary here, but this is right.)
(ii) If E does cause N1* and N1 =/= N1* then a law of nature is violated, since it is a law that E will cause N1. Moreover, the laws of nature are changed, since E causes something else than it normally would.
(iii) If E does cause N1* and N1 = N1* then no law of nature is violated yet, and we must look for the smallest i in the chain such that Ni =/= Ni*.
(iv) Again, such an i exists because of our identity criterion and the assumption of a different series S*. So Ni =/= Ni*. Then it will follow that Ni-1 = Ni-1*. So Ni-1 does not cause Ni. So a law of nature is violated, since it is a law that Ni-l will cause Ni.
Moreover, Ni-1 must cause Ni*, since this is a chain of neural events leading to a physical movement. By a metaphysically motivated syntactic rule for these representations of causal chains, there must be a '>' between every node in the chain. (If there were causal 'gaps' how could you really call it a causal chain; the only real causal chains would be the ones before and after the 'gap'.) So that means a law of nature is changed, since Ni-1 causes something different than it normally would.
So, no matter what, if the mind ever exercises the power it has to bring about another neural causal series, a law of nature must be violated. Moreover, if the first event in this series is caused then the laws of nature must be changed by the mind at some point. This is bad.
However, there's more to say than just that it's bad. Lowe could reply that, in the actual world, there are psychophysical laws which hold and which tell us the mind never actually uses this power of counterfactual control over laws. Thus, the normal patterns of events we observe still obey the laws of nature. The laws of nature continue to hold in this world.
But that leaves two options: (1) Does that mean minds never actually do anything? Are they causally effete and just let the world stay its course? Or else (2) Do minds still do something, and thereby contribute some causal influence? If they do, does that mean they cause the actual laws of nature to hold in the case of neural causal chains?
Both possibilities seem weird and unpalatable. If the first view is true that means mental causation never actually occurs in this world, though it could. On the second view there are two possibilities: Either (A) mental causation is superfluous, or else (B) laws of nature are really really weird.
On the one hand, it could be that the laws of nature by themselves are enough to explain why each event in the series causes the next, in which case the mental decision is superfluous and just 'backs up' the law of nature by its influence. The mind gives the laws of nature more 'oomph', though they are completely sufficient even without this 'oomph' at all. This would be case (A).
On the other hand, it could be that, once we move from E to N1, all of a sudden the mind is needed to hold up the laws of nature from then on. This is option (B). And that seems weird. That would mean when the brain comes into play, all of a sudden the laws of nature by themselves aren't sufficient for producing later events and the influence of the mind is needed to 'keep them going'. When it comes to the brain, the laws of nature need crutches; the mind is a metaphysical crutch. This is very metaphorical of course, but the point could certainly be made more precisely.
To be fair, this theory can't be disproven by the science. Neither option (1) nor (2) above is even possibly ruled out by the actual scientific evidence. So maybe this is one way to reject causal completeness while holding a theory that is empirically equivalent. I'm not sure it's a plausible one though.
Saturday, October 18, 2014
The 'How Does it Work?' Objection to Dualism: #1 Different Substances
"How can the mind move the body?" This is one of the most familiar rhetorical questions for dualists about the mind. It is rhetorical since it is meant to make the point that dualists can't explain how the mind moves the body, and that this is a problem for dualism.
One problem is that this question is highly ambiguous. This is reflected in the literature by the fact that the phrase 'interaction problem' is used by different philosophers to refer to quite different arguments. When someone poses this question there are multiple objections someone could have in mind. Someone could be saying it's in principle impossible for dualists to provide an explanation. Or they could simply be saying there is no plausible candidate for an explanation. Or they could be saying it's very likely that non-physical causation never happens in our world. Moreover, they could pose these arguments for different reasons. So it's important to get clear on which objection we're talking about. I'll try to distinguish a few ways we can formulate this objection and then reply to these objections. In the first post I'll identify and respond to what I call the 'Different Substances Objection'.
#1: The Different Substances Objection
First, one might object that, since mind and matter on a dualist view are completely separate there is no way for them to interact. Everything is mental or material, but not both. So there could not be interaction between the two. The problem is that it's not generally true that entities from two mutually exclusive categories cannot interact causally. Everything is either a proton or a non-proton for instance, but that doesn't mean protons and non-protons cannot interact.
Another very similar form of this objection is that mind and matter are different types of substances, so the two cannot interact. Or a more particular version of this objection would say that the mind is non-extended and the body is extended, so the two cannot interact. One problem is that, in general, it is false that in order for substance x to interact with substance y of kind F, x must itself be of kind F. You don't need to be a human to interact with a human; you don't need to be a proton to interact with a proton; etc.
A final and more sophisticated way to formulate this version of the objection is that since mind and matter share no intrinsic properties, the two cannot interact. First of all, the main premise of this argument is not true. Being a substance is common to both our minds and our brains. Having causal powers is intrinsic to both (note: one need not presuppose causation between mind and body occurs to hold this is true, since one should at least admit mental to mental causation). They both have the property of having metaphysical components. Of course, they don't share any intrinsic physical properties (since the mind does not have physical properties). But at least some of what I have listed are plausibly intrinsic properties.
More importantly though, why do two substances have to have common intrinsic properties to causally interact? This principle would have to be motivated by some more general theory where two substances' having common intrinsic properties P1, ... , Pn plays a relevant role in their ability to engage in causal interaction. In particular, to be relevant, if x causes change C in y in some way, then these P1, ... , Pn must contribute some causal influence to C. I'm not sure how else one would motivate the main premise here.
But we can imagine situations where the common intrinsic properties of agents plays no relevant role in the interaction of the two. For instance, even though a Jedi and a table share the intrinsic properties of having mass or volume or other physical properties, when the Jedi uses the Force he doesn't in any way seem to take advantage of his having mass or volume or his other physical properties. Of course, this is just an imaginary situation, but it seems perfectly coherent and thus there can be no a priori reason for thinking common intrinsic properties must play a relevant role in all causal interaction (of course, this isn't to deny that sometimes they do).
In fact, there might be some cases which are actual counterexamples. For instance, consider the EPR paradox cases from quantum mechanics. Suppose you have a source emitting an electron-positron pair in a state of quantum entanglement, where the spin of each is anti-correlated with the other. In other words, if electron e has upward spin then p has downward spin, and if e has downward spin then p has upward spin. Suppose moreover you have two observers A and B in different locations who can measure the spin of the particles along some axis Z, and e is sent to A while p is sent to B. If A measures e as having an upward spin then B will measure p as having a downward spin with 100% probability. On the other hand, if A measures e as having downward spin, B will measure p as having upward spin with 100% probability. Since experimentation and Bell's Theorem rule out local causal explanation here, and supposing there is causal interaction between e and p, there must be some causation here where local intrinsic properties such as mass, volume, velocity, etc. do not play a role in the causal interaction.
Of course, the particles do share the intrinsic properties of having spin. But it's not e's simply having spin which contributes causal influence to p's particular spin; rather, it is e's having an upward or downward spin which does so. For what the spin of p is depends on the actual spin of e. So it isn't clear that we can identify some common intrinsic property of e and p where's e's having this property causally influences p's having a particular spin.
This seems to me to be an adequate reply to the different substances objection. In the next post I'll talk about what I call the 'No Mechanism Objection', which poses the problem that there seems to be no familiar model which could make causal interaction between the mind and the body intelligible.
One problem is that this question is highly ambiguous. This is reflected in the literature by the fact that the phrase 'interaction problem' is used by different philosophers to refer to quite different arguments. When someone poses this question there are multiple objections someone could have in mind. Someone could be saying it's in principle impossible for dualists to provide an explanation. Or they could simply be saying there is no plausible candidate for an explanation. Or they could be saying it's very likely that non-physical causation never happens in our world. Moreover, they could pose these arguments for different reasons. So it's important to get clear on which objection we're talking about. I'll try to distinguish a few ways we can formulate this objection and then reply to these objections. In the first post I'll identify and respond to what I call the 'Different Substances Objection'.
#1: The Different Substances Objection
First, one might object that, since mind and matter on a dualist view are completely separate there is no way for them to interact. Everything is mental or material, but not both. So there could not be interaction between the two. The problem is that it's not generally true that entities from two mutually exclusive categories cannot interact causally. Everything is either a proton or a non-proton for instance, but that doesn't mean protons and non-protons cannot interact.
Another very similar form of this objection is that mind and matter are different types of substances, so the two cannot interact. Or a more particular version of this objection would say that the mind is non-extended and the body is extended, so the two cannot interact. One problem is that, in general, it is false that in order for substance x to interact with substance y of kind F, x must itself be of kind F. You don't need to be a human to interact with a human; you don't need to be a proton to interact with a proton; etc.
A final and more sophisticated way to formulate this version of the objection is that since mind and matter share no intrinsic properties, the two cannot interact. First of all, the main premise of this argument is not true. Being a substance is common to both our minds and our brains. Having causal powers is intrinsic to both (note: one need not presuppose causation between mind and body occurs to hold this is true, since one should at least admit mental to mental causation). They both have the property of having metaphysical components. Of course, they don't share any intrinsic physical properties (since the mind does not have physical properties). But at least some of what I have listed are plausibly intrinsic properties.
More importantly though, why do two substances have to have common intrinsic properties to causally interact? This principle would have to be motivated by some more general theory where two substances' having common intrinsic properties P1, ... , Pn plays a relevant role in their ability to engage in causal interaction. In particular, to be relevant, if x causes change C in y in some way, then these P1, ... , Pn must contribute some causal influence to C. I'm not sure how else one would motivate the main premise here.
But we can imagine situations where the common intrinsic properties of agents plays no relevant role in the interaction of the two. For instance, even though a Jedi and a table share the intrinsic properties of having mass or volume or other physical properties, when the Jedi uses the Force he doesn't in any way seem to take advantage of his having mass or volume or his other physical properties. Of course, this is just an imaginary situation, but it seems perfectly coherent and thus there can be no a priori reason for thinking common intrinsic properties must play a relevant role in all causal interaction (of course, this isn't to deny that sometimes they do).
In fact, there might be some cases which are actual counterexamples. For instance, consider the EPR paradox cases from quantum mechanics. Suppose you have a source emitting an electron-positron pair in a state of quantum entanglement, where the spin of each is anti-correlated with the other. In other words, if electron e has upward spin then p has downward spin, and if e has downward spin then p has upward spin. Suppose moreover you have two observers A and B in different locations who can measure the spin of the particles along some axis Z, and e is sent to A while p is sent to B. If A measures e as having an upward spin then B will measure p as having a downward spin with 100% probability. On the other hand, if A measures e as having downward spin, B will measure p as having upward spin with 100% probability. Since experimentation and Bell's Theorem rule out local causal explanation here, and supposing there is causal interaction between e and p, there must be some causation here where local intrinsic properties such as mass, volume, velocity, etc. do not play a role in the causal interaction.
Of course, the particles do share the intrinsic properties of having spin. But it's not e's simply having spin which contributes causal influence to p's particular spin; rather, it is e's having an upward or downward spin which does so. For what the spin of p is depends on the actual spin of e. So it isn't clear that we can identify some common intrinsic property of e and p where's e's having this property causally influences p's having a particular spin.
This seems to me to be an adequate reply to the different substances objection. In the next post I'll talk about what I call the 'No Mechanism Objection', which poses the problem that there seems to be no familiar model which could make causal interaction between the mind and the body intelligible.
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