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Rationally Speaking is a blog maintained by Prof. Massimo Pigliucci, a philosopher at the City University of New York. The blog reflects the Enlightenment figure Marquis de Condorcet's idea of what a public intellectual (yes, we know, that's such a bad word) ought to be: someone who devotes himself to "the tracking down of prejudices in the hiding places where priests, the schools, the government, and all long-established institutions had gathered and protected them." You're welcome. Please notice that the contents of this blog can be reprinted under the standard Creative Commons license.

Saturday, December 29, 2012

Science and metaphysics


by Massimo Pigliucci

Afternoon time at the annual meeting of the American Philosophical Association. I’m following the session on science and metaphysics, chaired by Shamik Dasgupta (Princeton). The featured speakers are Steven French (Leeds-UK), James Ladyman (Bristol-UK), and Jonathan Schaffer (Rutgers-New Brunswick).  I have developed a keen interest in this topic of late, though as an observer and commentator, not a direct participant to the discussion. Let’s see what is going to transpire today. A note of warning: what follows isn't for the (metaphysically) faint of heart, and it does require at least some familiarity with fundamental physics.

We started with French on enabling eliminitavism, or what he called taking a Viking approach to metaphysics. (The reference to Vikings is meant to evoke an attitude of plundering what one needs and leave the rest; less violently, this is a view of metaphysics as helping itself to a varied toolbox.) French wishes to reject the claim made by others (for instance, Ladyman) that a prioristic metaphysics should be discontinued. However, he does agree with critics that metaphysics should take science seriously.

The problem French is concerned with, then, is how to relate the scientific to the ontological understanding of the world. Two examples he cited were realism about wave functions and the kind of ontic structural realism favored by Ladyman and his colleague Ross.

Ontic structural realism comes in at least two varieties: eliminativist (we should eliminate objects entirely from our metaphysics, particles are actually "nodes" in the structure of the world) and non-eliminativist (which retains a "thin" version of objects, via the relations of the underlying structure).

French went on to talk about three tools for the metaphysician: dependence, monism, and an account of truth making.

Dependence. The idea is that, for instance, particles are "dependent" for their existence on the underlying structure of the world. A dependent object is one whose features are derivative on something else. In this sense, eliminitavism looks viable: one could in principle "eliminate" (ontologically) elementary particles by cashing out their features in terms of the features of the underlying structure, effectively doing away with the objects themselves.

The basic idea, to put it as French did, is that "if it is of the essence, or nature or constitution of X that it exists only if Y exists, so that X is dependent on Y in the right sort of way, then X can be eliminated in favor of Y + structure."

As French acknowledged, however (though he didn't seem sufficiently worried about it, in my opinion), the eliminativist still needs to provide an account of how we recover the observable properties of objects above the level of fundamental structure.

Monism. This is the (old) idea that the world is made of one kind of fundamental stuff, a view recently termed "blobjectivism" (everything reduces to a fundamental blob). As French put it, this is saying that yes, electrons, for instance, have charges, but there really are no electrons, there is just the blob (that is, the structure).

A number of concerns have been raised against monism, and French commented on a few. For instance, monism can't capture permutations in state space. To which the monist responds that monistic structure includes permutation invariance. This, however, strikes me as borderline begging the question, since the monist can always use a catch all "it's already in the structure" response to any criticism. But how do we know that the blob really does embody this much explanatory power?

Truthmakers. French endorses something called Cameronian truthmaker theory, according to which < X exists > might be made true by something other than X. Therefore, the explanation goes, < X exists > might be true according to theory T without X being an ontological commitment of T.

Perhaps this will be made clearer by looking at one of the objections to this account of truth making: the critic can reasonably ask how is it possible that there appear to be things like tables, chairs, particles, etc. if these things don't actually exist. French's response is that one just needs to piggyback on the relevant physics, though it isn't at all settled that "the relevant physics" actually says that tables, chairs and particles don't exist in the strong eliminativist sense of the term (as opposed to, say, they exist as spatio-temporal patterns of a certain kind, accessible at the relevant level of analysis).

Next we moved to Ladyman, on "between eliminativism and monism: the radical middle ground." He acknowledged that structural realism is accused by some of indulging in mystery mongering, but Ladyman responded (correctly, I think) that it is physics that threw up stuff —  like fundamental relations and structure — that doesn't fit with classical metaphysical concepts, and the metaphysician now has to make some sense of the new situation.

Ladyman disagrees with French's eliminativism about objects, suggesting that taking structure seriously doesn't require to do away with objects. The idea is that there actually are different versions of structuralism, which depend on how fundamental relations are taken to be. James also disagrees with the following speaker, Schaffer, who is an eliminativist about relations, giving ontological priority to one object and intrinsic properties (monism). Ladyman's (and his colleague Ross') position is summarized as one of being non-eliminativist about metaphysically "thin" individuals, giving ontological priority to relational structures.

One of the crucial questions here is whether there is a fundamental level to reality, and whether consequently there is a unidirectional ontological dependence between levels of reality. Ladyman denies a unidirectional dependence. For instance, particles and their state depend on each other (that is, one cannot exist without the other), the interdependence being symmetrical. The same goes for mathematical objects and their relations, for instance the natural numbers and their relations.

As for the existence of a fundamental level, we have an intuition that there must be one, partly because the reductionist program has been successful in science. However, Ladyman thinks that the latest physics has rendered that expectation problematic. Things got more and more messy in fundamental physics of late, not less so. Consequently, for Ladyman the issue of a fundamental level is an open question, which therefore should not been built into one's metaphysical system — at least not until physicists settle the matter.

Are elementary quantum particles individuals? Well, one needs to be clear on what one means by individual, and also on the relation between the concept of individuality and that of object. This is a question that is related to that old chestnut of metaphysics, the principle of identity of indiscernibles (which establishes a difference between individuals — which are not identical, and therefore discernible — and mere objects). However, Ladyman collapses individuals into objects, which is why he is happy to say that — compatibly with quantum mechanics — quantum particles are indeed objects. The idea is that particles are intrinsically indiscernible, but they are (weakly) discernible in virtue of their spatio-temporal locality. 

Ladyman, incidentally, is aware of course of the quantum principle of non-locality, which makes the idea of precisely individuated particles problematic. But he doesn't think that non-locality licenses a generic holism where there is only one big blob in the world, and that individuality can be recovered by thinking in terms of a locally confined holism. Again, that strikes me as sensible in terms of the physics (as I understand it), and it helps recovering a (thin, as he puts it) sense in which there are objects in the world.

Finally, we got to Schaffer, who argued against ontic structural realism of the type proposed by either French or Ladyman. He wants to defend the more classical view of monism instead. He claimed that that is the actual metaphysical picture that emerges from current interpretations of quantum mechanics and general relativity.

His view is that different mathematical models — both in q.m. and in g.r. — are best thought of as just being different notations related by permutations, corresponding to a metaphysical unity. In a sense, these different mathematical notations "collapse" into a unified picture of the world.

Schaffer's way to cash out his project is by using the (in)famous Ramsey sentences, which are sentences that do away with labels, not being concerned with specific individuals. Now, one can write the Ramsey sentences corresponding to the equations of general relativity, which according to the author yields a picture of the type that has been thought of since at least Aristotle: things come first, relations are derivative (i.e., one cannot have structures or relations without things that are structured or related). If this is right, of course, the ideas that there are only structures (eliminitavism a la French) or that structures are ontologically prior to objects (Ladyman) are incorrect.

So, Schaffer thinks of Ramsey sentences as describing structural properties, which he takes to be the first step toward monism. Second, says Schaffer, what distinguishes abstract structures from the one describing the universe is that something bears those structures. That something is suggested to be the largest thing we can think fits the job, that is the universe as a whole. He calls this picture monistic structural realism: there is a cosmos (the whole), characterized by parts that bear out the structures qualitatively described by the Ramsey translation of standard physical theories like relativity and quantum mechanics. Note that this is monism because — thanks to the Ramsey translation — the parts are interchangeable, related by the mathematical permutations mentioned above.

Okay, does your head spin by now? This is admittedly complicated stuff, which is why I added explanatory links to a number of the concepts deployed by the three speakers. I found the session fascinating as it gave me a feeling for the current status of discussions in metaphysics, particularly of course as far as it concerns the increasingly dominant idea of structural realism, in its various flavors. Notice too that none of the participants engaged in what Ladyman and Ross (in their Every Thing Must Go, about which I have already commented) somewhat derisively labeled "neo-Scholasticism," that is the entire discussion took seriously what comes out of physics, all participants conceptualizing metaphysics as the task of making sense of the broad picture of the world that science keeps uncovering. That seems to me to be the right way of doing metaphysics, and one that may (indeed should!) appeal even to scientists.

31 comments:

  1. I'm not sure what the difference is between "structure" and "object". It seems to me that the most fundamental ontological difference is between something and nothing. Both structure and object are something, while their absence is nothing.

    Isn't object just an appearance of structure in our consciousness? Then the difference between object and structure lies in the phenomenon of consciousness: structure appears as object in our consciousness. The phenomenon of consciousness continues to be debated and investigated, but we can already say that consciousness has certain limits. For example, when we see an object such as a table we are not able to consciously differentiate its microscopic structure (for example atoms or subatomic particles) but we are conscious of its macroscopic properties like color, texture, shape, and we experience the total of these macroscopic properties as an object which we call a table.

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    1. Tomas,

      > I'm not sure what the difference is between "structure" and "object". <

      For a structural realist, structure is all there is. But if you are a monist, there can't be structure without objects.

      > seems to me that the most fundamental ontological difference is between something and nothing <

      It's really not clear, physically or philosophically, what it would mean for there to be "nothing."

      > Then the difference between object and structure lies in the phenomenon of consciousness <

      That's a much higher level of analysis than this symposium was concerned with: the discussion was about fundamental physics, not biology or cognitive science.

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    2. Massimo,

      "For a structural realist, structure is all there is. But if you are a monist, there can't be structure without objects."

      If monists feel the need to postulate objects in addition to structure, what is the difference between objects and structure?

      "It's really not clear, physically or philosophically, what it would mean for there to be "nothing.""

      I imagine "nothing" as absence of differences. That means no entities, and hence no structure. It also means no objects, because whatever "object" means, I guess it is still differentiated from what it is not.

      Equivalent descriptions of nothing might be: perfect symmetry, perfect homogeneity, zero information. Some might argue that nothing should have no property but I think this is nonsense; nothing should have the property of being nothing. I suggest that this is the no-differences property. This property differentiates nothing from something, which is the presence of differences (or: broken symmetry, heterogeneity, non-zero information).


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  2. Massiomo,

    >Ladyman disagrees with French's eliminativism about objects, suggesting that taking structure seriously doesn't require to do away with objects<

    >Ladyman denies a unidirectional dependence. For instance, particles and their state depend on each other (that is, one cannot exist without the other)<

    >But he [Ladyman] doesn't think that non-locality licenses a generic holism where there is only one big blob in the world, and that individuality can be recovered by thinking in terms of a locally confined holism. Again, that strikes me as sensible in terms of the physics (as I understand it), and it helps recovering a (thin, as he puts it) sense in which there are objects in the world.<

    My understanding is that Ladyman thinks "individuality can be recovered by thinking in terms of a locally confined holism.", and that's what you are referring to as sensible.

    If I'm following, Do you think Ladyman is supporting neither ESR nor OSR but rather something like : we can know things to a certain degree from a certain perspective, and, structure and relations cannot exist without a certain degree of thingness?

    [A crude statement of ESR is the claim that all we know is the structure of the relations between things and not the things themselves, and a corresponding crude statement of OSR is the claim that there are no ‘things’ and that structure is all there is (this is called ‘radical structuralism’ by van Fraassen 2006). http://plato.stanford.edu/entries/structural-realism/ ]

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  3. Massimo,

    I think I have more or less confirmed my understanding of Ladyman after listening to the link you included : http://www.rationallyspeakingpodcast.org/show/rs69-james-ladyman-on-metaphysics.html

    (... I missed it first time round)

    After listening to that, the web page from Stanford on Structural Realism is making a lot more sense. Ladyman appears to be backing a *version* of OSR that does not discount things but rather discounts that things have been shown to be a fundemental building block, eg "Ladyman and Ross (2007) argue that objects are pragmatic devices used by agents to orient themselves in regions of spacetime, and to construct approximate representations of the world.", and "Ladyman and Ross (2007) defend a version of OSR according to which science describes the objective modal structure of the world, where the latter is ontologically fundamental, in the sense of not supervening on the intrinsic properties of a set of individuals."

    I also like Psillos (1995) and Kyle Stanfordand's (2003) questioning, as I understand it, of Structural Realism's ability to reliably distinguish structural claims from claims about content or natures.

    [References and quotes from : http://plato.stanford.edu/entries/structural-realism/ ]

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  4. Tomas,

    > what is the difference between objects and structure? <

    It’s the same sort of difference that you find between relations and relata. If there are relations, there has to be — in the classic view — something that the relation applies to. So with structure: without objects this would be a structure of what?

    > I imagine "nothing" as absence of differences. <

    I think that’s not good enough. You could have a totally homogeneous substance (no differences), and yet you wouldn’t claim it were “nothing.”

    > Equivalent descriptions of nothing might be: perfect symmetry, perfect homogeneity, zero information. <

    Same problem, seems to me.

    Marc,

    > My understanding is that Ladyman thinks "individuality can be recovered by thinking in terms of a locally confined holism.", and that's what you are referring to as sensible. <

    Correct.

    > Ladyman appears to be backing a *version* of OSR that does not discount things but rather discounts that things have been shown to be a fundemental building block <

    Again, yes. Indeed, I asked James pretty much that question, and he confirmed that my understanding (and yours) is correct.

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    1. Massimo,

      > If there are relations, there has to be — in the classic view — something that the relation applies to. So with structure: without objects this would be a structure of what? <

      Aha, so you're saying that objects are the relata in a structure. It seems to me that relata and their mutual relations are inseparable, like figure and ground are inseparable from the relation between figure and ground. Relata are defined by their mutual relations; relations simply seem to be differences and commonalities between relata. Or in other words, a relatum is a set of differences and commonalities relative to other relata.

      By "objects" do you mean the same as "things", as in Ladyman and Ross's "Every Thing Must Go"?

      > You could have a totally homogeneous substance (no differences), and yet you wouldn’t claim it were “nothing.” <

      Why not? What would be a difference between a totally homogenous substance and nothing?


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  5. Regarding "nothing," the word 'nothing', like 'something' and 'everything', is not a referring term but a quantifier, so it makes no more sense to try to describe the referent of 'nothing' than it does to try to describe that of 'something' or 'everything'. These terms do not have referents. When one says one sees nothing, to illustrate, one means that there is no relevant something that one sees, not that one sees the something called 'nothing'. A better term to use regarding the absence of all existence is 'nothingness', but still I think it is a mistake to try to use the physical imagination to understand this term, in its universal sense at least, as there are no physical states, or states of any kind, in universal nothingness. We must understand the term cognitively, or logically, I think. We might say that universal nothingness is captured by a statement something like: Universal nothingness is the situation in which there is nothing that is something.

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  6. I can see at least one obvious objection to this eliminativist ontic structural realism. What does it mean for a structure to exist without objects? In other words, what does it mean for relations to exist without relata?

    I'm a little confused about non-eliminativist ontic structural realism. What does is mean for an object to exist thinly? Does it mean that the objects are created by the relations themselves, and objects don't exist independently of the relations? In that case why do we call them objects in the first place? But it's just a word so you can use anything you like. The more important question is what exactly is the difference between those thin objects, and the relations in the structure? What intrinsic property do those thin objects have that relations don't?

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  7. Maybe this is a sideways take on it but I always wondered what would have happened it Einstein had lived to see Bell's derivation of Bell's inequality. It really is a simple knockout argument that any theory that reproduces certain predictions of quantum mechanics must give up either locality or realism. The hard science of it cuts through the hopeless quagmire that is philosophy.

    A little confused about non-eliminativist ontic structural realism? I can see how that could happen.

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    1. Many world interpretation is a local, realist, and deterministic interpretation of QM that is very much like classical physics and is apparently the second most popular interpretation of QM after Copenhagen. So I'm not sure what you mean.

      But yeah, still confused about what non-eliminativist ontic structural realism really means.

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  8. Sorry, somehow I posted in the wrong place. I intended to comment on the counter factual stuff above. I got distracted and lost my place.

    I'm not sure manyworlds can really be called realist. After all you still have interference effects and violations of Bell's inequality. The universes don't split until you make measurements. Yet the most interesting effects in QM come when you avoid making measurements. In a sense it is like the particles may have realistic attributes in each universe but which universe you are in is not a realistic variable until it is measured.

    Put simpler the universes mix and interfere in the unmeasured spaces in a way to kill realism anyway.

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    1. I'm not sure by what you mean by realism here. Here's what I mean. According to the Many World Interpretation, the wavefunction really does exist, and it evolves according to the Schrodinger equation and never collapse. In the Copenhagen interpretation, the wavefunction evolves according to the wavefucntion until it collapses because of some not properly defined phenomena called "measurement." Many World is therefore the more straightforward interpretation.

      Also, according to MWI, the wavefuction splits regardless of whether there is observers to observe it, unlike von Neumann (who was one of the most brilliant even among them) for example, who thought consciousness collapses the wavefunction. So I'm don't see why you think measurement is a problem for MWI being realist. The wavefunction is real and it evolves the same way regardless of whether there are conscious observers to observe it evolve and split.

      There's also the fact that early quantum physicists were really really anti-realist. Schrodinger didn't make his cat thought experiment to show that QM was weird, but to show that it is ridiculous to think of the wavefunction as something real. Everett on the other hand took the wavefunction as real when he made MWI.

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  9. Tomas,

    > so you're saying that objects are the relata in a structure. It seems to me that relata and their mutual relations are inseparable <

    That’s one way to see it. For ontic structural realists, however, relations are ontologically prior to relate, so that there is a sense in which one can talk about relations without relata, as counterintuitive as it sounds.

    > Relata are defined by their mutual relations; relations simply seem to be differences and commonalities between relata. <

    Those two statements seem somewhat at odds with each other. The first one seems to give ontological priority to relations (the ontic structural realists would agree), while the second one is similar to the Aristotelian view according to which relata have ontological priority.

    > By "objects" do you mean the same as "things", as in Ladyman and Ross's "Every Thing Must Go"? <

    Yes.

    > What would be a difference between a totally homogenous substance and nothing? <

    The substance, which would clearly not be nothing, at least not in the sense in which I understand the word. Nothing means the absence of any substance, no matter how homogeneous.

    brainoil,

    > I can see at least one obvious objection to this eliminativist ontic structural realism. What does it mean for a structure to exist without objects? <

    That’s not obvious at all. See Ladyman and Ross’ book for how they very carefully deal with it (and by the way, their claim is that the best physics available hints at that conclusion, not just metaphysical speculation).

    > What does is mean for an object to exist thinly? <

    Again, see the book, but the idea is related to the concept of non-locality in quantum mechanics.

    > What intrinsic property do those thin objects have that relations don't? <

    Well, you have to somehow recover the sense of materiality that most science and everyday experience gives us.

    ppnl,

    > The hard science of it cuts through the hopeless quagmire that is philosophy. <

    Frankly, I’m so tired of this sort of anti-intellectual statements, usually made by people who have never read a single philosophy paper, that I will not respond.

    > I'm not sure manyworlds can really be called realist. <

    You are not using the word “realist” in the sense of this debate (see my comment above about philosophy and knowing something about it). Realism in philosophy of science refers to whether a theory reflects the world as it is, it doesn’t refer to the world itself.

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    1. Massimo,

      I'm sorry if it seemed I was being overcritical of philosophy in general. I do think philosophy is important. But I also think of philosophy as mostly a discussion of how words should be deployed. Because philosophy has very little in the way of an empirical component to keep it connected to reality it can easily become disconnected.

      I should also remind you that my original post was in the wrong place. I had intended to reply to your post about counterfactual philosophers. I introduced a counterfactual Einstein who lived to see Bell's inequality. The fact that I posted it in the wrong place changed the tone and generated confusion.

      I also agree that I used "realist" in a very different way than you did. But in context it was reasonable since I was discussing brainoil's claim that manyworlds was a realistic theory of quantum mechanics. Off topic maybe but reasonable in context.

      Again, sorry I got lost and posted under the wrong blog entry. My error generated maximum avoidable confusion while adding very little.

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    2. ppnl,

      no worries, I have become a bit oversensitive about that sort of statement, often made by people who comment here, a blog devoted to the intersection of philosophy and science, of all things!

      Philosophy is a bit more than just the elucidation of word meanings - though Wittgenstein would have been happy with that view. Particularly philosophy of science gets very much into the nitty gritty of science theorizing and its logic.

      The idea of counterfactual scientists is similar to that of counterfactual philosophers, as I pointed out in the main post when I was talking about the possibility of a physics without quarks. But since philosophy moves in logic rather than empirical space, the weight of unexplored arguments is even more relevant than in science.

      Yes, one can use the term "realism" in the context of discussions of interpretations of quantum mechanics, as long as we are clear that we are not referring to what philosophers of science call realism. Cheers!

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    3. Massimo,

      I may have to read the book, and I may. I'm simply raising some of the objections one might come up with against eliminativist ontic structural realism. Another objection one might make against eliminativist theory is that it would mean we shouldn't use set theory when we formulate physical theories because set theory needs objects to work with. Then it becomes a problem of logic.



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  10. Massimo,

    > Those two statements seem somewhat at odds with each other. The first one seems to give ontological priority to relations (the ontic structural realists would agree), while the second one is similar to the Aristotelian view according to which relata have ontological priority. <

    As I said, relations and relata are inseparable in my view, so I don't give ontological priority to either. Is there a philosophical term for this view? :)

    > Nothing means the absence of any substance, no matter how homogeneous. <

    It seems to me redundant to postulate a substance that has no discernible properties (any discernible property would introduce a difference/heterogeneity).

    Maybe the idea of such a substance was inspired by the phenomenon of qualia: if there existed nothing but a homogeneous quale, for example red color, then there would be no discernible difference anywhere and yet we would agree that it is not nothing. However, note that the existence of a quale requires the existence of consciousness, which probably requires the existence of differences (like neurons or other information-processing structures) and in the case of color, there also must exist electromagnetic waves of a specific wavelength (differences in space and time). A homogeneous substance alone seems unable to provide consciousness and thus qualia.


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    1. > relations and relata are inseparable in my view, so I don't give ontological priority to either. <

      Yes, but people disagree, and some of that disagreement comes straight out of fundamental physics.

      > It seems to me redundant to postulate a substance that has no discernible properties <

      I wasn't the one postulating a homogeneous substance. But if one does, it seems to me that now we have something, not just nothing, regardless of whether there is anyone around to perceive it (this has really nothing to do with consciousness or qualia).

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  11. >relations and relata are inseparable in my view<

    Hmm, well relations are abstractions and so can in principle be instantiated any many very different substances or relata.

    For example a computer program can model a tornado and so recreate the vast network of relationships in a pattern of charging and discharging capacitors. In a mathematical sense there is an isomorphism between the program and the tornado dispite the fact they are very different substances or relata.

    So what is real, the relationship or the substance? Maybe the entire universe is just a computer program and actual atoms, planets and galaxies are just patterns of abstract data playing out in a memory bank.

    From a scientific point of view it is an uninteresting question unless you can devise a test in principle. Philosophers are free to argue the point but it isn't clear what purpose it would serve.

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    1. ppnl,

      > For example a computer program can model a tornado and so recreate the vast network of relationships in a pattern of charging and discharging capacitors. In a mathematical sense there is an isomorphism between the program and the tornado dispite the fact they are very different substances or relata. <

      The pattern that is the computer program and the pattern that is the tornado may share some relations but probably not all. For example, their relata with respect to space are different. That's one of the reasons why a tornado in Kansas can knock down a house there but its simulation running on a computer program cannot.

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  12. brainoil,

    > I'm not sure by what you mean by realism here. <

    As I mentioned in another comment above, the term “realism” in the context of this discussion (philosophy of science) does not have anything at all to do with different interpretations of quantum mechanics. I explained above what the term means to people like Ladyman, Ross, et al.

    > I'm simply raising some of the objections one might come up with against eliminativist ontic structural realism. <

    Not if you are using the wrong meaning of “realism.”

    > Another objection one might make against eliminativist theory is that it would mean we shouldn't use set theory when we formulate physical theories because set theory needs objects to work with. <

    No, it doesn’t. Set theory works perfectly well with mathematical (i.e., non physical) entities, a type of “object” that ontic structural realists would be perfectly happy with.

    ppnl,

    > From a scientific point of view it is an uninteresting question unless you can devise a test in principle. Philosophers are free to argue the point but it isn't clear what purpose it would serve. <

    The “purpose” of philosophy is not to solve scientific problems, we’ve got science for that. And of course the charge of “what for?” can be leveled to almost anything, including much science, which is essentially irrelevant either to human life or even to the pursuit of grand knowledge (as in final theories and such). So let’s not play the “what for?” game, *it* is truly useless.

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  13. Massimo,


    >Set theory works perfectly well with mathematical (i.e., non physical) entities, a type of “object” that ontic structural realists would be perfectly happy with.<

    So... Platonism?

    >The “purpose” of philosophy is not to solve scientific problems,...<

    Actually I think philosophy is very useful for solving scientific problems. More precisely it allows us to explore the metaphysical consequence of theory. For example why did it take so long for Bell's inequality to be derived? The math could be understood by your average high school. I think physicists were lost in the mathematical formalism and needed to step back from it.

    Now maybe you can have applied philosophy and pure philosophy to mirror applied math and pure math. But physics has empirical reality to keep it connected. Math has axioms and consistency to keep it connected in a different way. Philosophy has neither of these. It can easily become disconnected from ... what? Reality? Relevance? It can easily become a word salad and there is no procedure that allows you to tell the difference.

    >As I mentioned in another comment above, the term “realism” in the context of this discussion (philosophy of science) does not have anything at all to do with different interpretations of quantum mechanics.<

    Actually I think that is going a little far. Realism in QM is a very specific well defined thing. Realism in philosophy may cover a vast penumbra of possible related meanings and their consequence. Physicists took one specific example of realism from philosophy and applied it.

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    1. > So... Platonism? <

      Yup. Ladyman & Ross barely mention it in the book, but I asked James in the podcast, and yes, some form of naturalistic mathematical Platonism is indeed highly compatible with ontic structural realism. I personally have no problem with that.

      > Actually I think philosophy is very useful for solving scientific problems. More precisely it allows us to explore the metaphysical consequence of theory. <

      Oh I agree, but that's really philosophy of science, not science per se. Yes, the boundary is fuzzy, as one might expect it to be. Let's put it this way: a physicists who studies quantum mechanics could subscribe to the "shut up and calculate" view (many do!) that does away with any interpretation of q.m. But curious minds want to know, and interpreting the theory comes close to the borderlands btw science and philosophy.

      > physics has empirical reality to keep it connected. Math has axioms and consistency to keep it connected in a different way. Philosophy has neither of these. <

      I disagree, good philosophy has both, since it is about applying good reasoning (logic) to the best background factual information available (science), and reflect on the implications and consequences.

      > Realism in QM is a very specific well defined thing. Realism in philosophy may cover a vast penumbra of possible related meanings and their consequence. <

      The latter part is simply not the case. Check the entries on realism in the Stanford Encyclopedia of Philosophy and you will see that the meaning(s) of the concept are perfectly clear.

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    2. Massio,

      So if you believe platonism, do you also believe that we live in a Tegmark level IV multiverse? Because that it seems to me that you cannot believe platonism and then deny level IV multiverse.

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    3. Interesting analogy. Tegmark's universe, however, is a bit stronger than just mathematical Platonism, it also requires mathematical monism (the idea that the only things that exist are mathematical structures). Ladyman and Ross wouldn't go that far, because of their "thin" notion of physical objects.

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    4. Massimo, I haven't yet read Ladyman's book, but I listened to your podcast with him (I've come to love yours and Julia's podcast series by the way).

      It seems to me that Ladyman wouldn't deny Tegmark level IV multiverse. He'd be agnostic about it. This is because in the podcast he said he's agnostic about platonism and Pythagoreanism (a term I learnt for the first time. Apparently it means that there's no distinction between abstract models of structures and concrete structures of physics). If he's agnostic about that, I suppose he'd be agnostic about Tegmark level IV as well.

      Secondly, having not read the book, I can't yet comprehend the exactly eliminativist OSR (which sounds like a sort of monism to me), is different from non-eliminativist OSR. This is because I don't know how they derive these thin-objects. I must say, I'm very open to monism, and pretty sure that QM destroyed the concept of individual objects, though there's some debate about this. What I really find interesting in the podcast was your discussion about emergence.

      You said you were looking for a middle ground between reductionism and strong-emergence. However, in an earlier podcast, I think you were quite open to strong emergence, talking about how water has properties that cannot be reduced to H and O. In any case, I think that middle ground has a name: weak emergence. Weak emergence really isn't that different from reductionism.

      Ladyman on the other hand seems to be pure reductionist. He says that it makes sense to think that tables are real. But this is not because they cannot be reduced to smaller entities and then ultimately to the structure, but because it makes sense to track observations that way at the level humans work. The table doesn't exist as something that cannot be reduced to the underlying structure.

      What he's really against is idea reductionism, and that makes sense. Lot of people who are reductionists aren't idea reductionists, myself included. Scientific theories are ideas and I don't think that the ideas of special sciences, which are approximations (Ladyman takes theories about gases for example), could be reduced to the ideas presented in fundamental physics.

      However I think he's wrong about the Laplace's demon not being able to know everything, even according to his own worldview. In the absence of strong emergence, the demon would be able to exactly predict the nature of a particular configuration (of particles, thin-objects or whatever) such as a human being. It would be able to predict how that configuration creates approximate concepts, such as the concept of self, and approximate theories, such as theories about gases that Ladyman talks about. The demon won't miss anything by knowing everything.

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    5. brainoil,

      just a few brief comments since new threads have developed in the meantime concerning more recent posts:

      > It seems to me that Ladyman wouldn't deny Tegmark level IV multiverse. <

      Probably, and neither would I, though I don't really see how one would test that sort of hypothesis.

      > I can't yet comprehend the exactly eliminativist OSR (which sounds like a sort of monism to me), is different from non-eliminativist OSR. This is because I don't know how they derive these thin-objects. <

      Eliminativist OSR is not monism, since it concludes that there are no objects at all (monism says there is one "thing" with parts). As I said, the thin-object thing has to do with non-locality and its effects in nearby regions of space, but you may need to read the book (or at least some of the technical papers that Ladyman and Ross have put out in the last few years).

      > in an earlier podcast, I think you were quite open to strong emergence <

      Yes, the more I think about it, the more I think there are good reasons to go for strong emergence.

      > I think he's wrong about the Laplace's demon not being able to know everything <

      I think he derives that from entanglement and non-locality. It convinced me.

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  14. > Realism in QM is a very specific well defined thing. Realism in philosophy may cover a vast penumbra of possible related meanings and their consequence. <

    The latter part is simply not the case. Check the entries on realism in the Stanford Encyclopedia of Philosophy and you will see that the meaning(s) of the concept are perfectly clear.<

    Wow, its hard to see how we are reading the same text.

    First sentence, first paragraph:

    "The question of the nature and plausibility of realism arises with respect to a large number of subject matters, including ethics, aesthetics, causation, modality, science, mathematics, semantics, and the everyday world of macroscopic material objects and their properties."

    In short "realism" refers to all the word games you can play with the word "real".

    Second sentence, first paragraph:

    "Although it would be possible to accept (or reject) realism across the board, it is more common for philosophers to be selectively realist or non-realist about various topics: thus it would be perfectly possible to be a realist about the everyday world of macroscopic objects and their properties, but a non-realist about aesthetic and moral value."

    Philosophers pick and choose what they are realist about. Some physicists reject the reality of particles entirely and this really is a very narrow application of philosophical realism. Earnst Mach denied that space existed as an ontological thing but was rather just a relationship between objects that we perceived as space. Again this was a philosophical position regarding a very narrow application of realism.

    The next three sentences:

    "In addition, it is misleading to think that there is a straightforward and clear-cut choice between being a realist and a non-realist about a particular subject matter. It is rather the case that one can be more-or-less realist about a particular subject matter. Also, there are many different forms that realism and non-realism can take."

    Exactly so. Mach for example rejected the realism of space because it was only a relationship. But you could accept Mach's premiss yet reject his conclusion if you believe relationships are the only thing that exists anyway.

    There is a vast penumbra of word games that you can play with the word "exist". Does the moon exist? Probably. Does space exist? Maybe, but not in the same way that the moon exists. Does time exist? Maybe in sorta kinda the way space exists. Does superman exist? Violate the intellectual property and find out. But again a very different thing than the existence of the moon.

    Philosophy uses logic but ultimately it is about language and word games.

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    Replies
    1. > its hard to see how we are reading the same text. <

      Not really. You are talking about the general concept of realism. I am talking abut realism in philosophy of science, which is the only one pertinent to the ongoing discussion.

      > Philosophers pick and choose what they are realist about <

      They don't "pick and choose," they present arguments for, e.g., realism about scientific theories but anti-realism about moral facts.

      > Philosophy uses logic but ultimately it is about language and word games. <

      That's a Wittgensteinian position that I find a bit too narrow for my taste.

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  15. a better thread thanks to ppnl, who sems to understand the unncessary hair splitting of philosophy and its mire of jargon. philosophy is a game that can be of use to science but it is generally just a mire, at least a practised today.

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