• Posty McPostface
    5.1k
    I've never really seen anyone affirm definitely the fact that QM can be used to justify the concept of having a 'free will'. I have seen some refutations of the PoSR (Principle of Sufficient Reason), which is the groundrock belief upon which determinism or necessitarianism hinge upon.

    So, can it be affirmatively asserted that QM affirms the concept of having a 'free will'?
  • Posty McPostface
    5.1k
    I would post this elsewhere where talk about physics is mentioned; but, other forums aren't as philosophical as this one or allow talk about philosophy.
  • StreetlightX
    3.1k
    QM makes the idea of free will even more implausable, not less:

    "[One must] reject the common sop that somehow the indeterminism of quantum physics helps us out here. First, there is no evidence that the neurons of the brain are subject to indeterminancy in the way, say, firing of elections is (and in fact there is much evidence against it); even if that were the case, however ... the indeterminancy of some outcomes in the brain would not help with establishing personal causal origination of actions. For randomness in fact would make us more rather than less subject to unexpected turns of fact. ...

    Moreover, human free choice would not be made possible by neuronal randomness in any case (and all the evidence so far seems to be against it) because no conscious human choice could ever operate to refashion neural networks directly at the neuronal level. Neural networks change through experience, not through will. ... We do not have direct access to neurons and their patterns of firing any more than we have the capacity for direct intervention into the functioning of our liver, even if the liver sometimes were to function randomly". (Heidi Ravven, The Self Beyond Itself)
  • MetaphysicsNow
    315
    QM indeterminacy, whatever else it does, neither affirms nor denies free will. QM is in general entirely irrelevant to most fundamental metaphysical questions. Interpretations of QM themselves rest on assumptions about answers to those questions. I'm not sure how the principle of sufficient reason is undermined by QM either, unless you equate "reason" with "determinate cause", which there is no sufficient reason for doing :wink:
  • Fool
    65
    @StreetlightX

    I hesitate to opine on this bc I know nothing about neuroscience, but I feel very sympathetic to what you said.
  • Hanover
    4k
    I've never really seen anyone affirm definitely the fact that QM can be used to justify the concept of having a 'free will'. I have seen some refutations of the PoSR (Principle of Sufficient Reason), which is the groundrock belief upon which determinism or necessitarianism hinge upon.

    So, can it be affirmatively asserted that QM affirms the concept of having a 'free will'?
    Posty McPostface

    The indeterminacy of QM offers nothing in explaining the contradictory nature of free will. Free will asserts both something occurring outside the causal chain as well as the agent's control, and therefore responsibility, over that event, which is to suggest a God-like property that defies explanation.

    Consider if the laws of nature forced you into a Choice A, then we'd say you lacked responsibility and control over the act. Why though would you say anything differently than if your choice were determined by the flip of a coin or a truly indeterminate event?
  • T Clark
    3k
    So, can it be affirmatively asserted that QM affirms the concept of having a 'free will'?Posty McPostface

    Free will is what @tim wood, R.G. Collingwood, and I call an absolute presupposition. As Collingwood says "...the distinction between truth and falsehood does not apply to absolute presuppositions at all..." He also says ""Absolute presuppositions are not verifiable. This does not mean that we should like to verify them but are not able to; it means that the idea of verification is an idea which does not apply to them...."
  • Pierre-Normand
    1.4k
    The indeterminacy of QM offers nothing in explaining the contradictory nature of free will. Free will asserts both something occurring outside the causal chain as well as the agent's control, and therefore responsibility, over that event, which is to suggest a God-like property that defies explanation.Hanover

    I think this is a problem that afflict some libertarian (so-called) 'contra-causal' conceptions of free will. According to such conceptions, while most natural events are governed by universal laws, acts of the will interfere with the working of those laws such that, in the case where an agent did something, if the history of the universe were to be rolled-back to its initial state before the person acted, then, in those exact same 'circumstances', the possibility that she could have done otherwise remains open; and the counterfactual actualization of this possibility also is being construed as the manifestation of an act of the agent's will. (This is one possible construal of the principle of alternative possibilities, of PAP).

    The main trouble with this conception relates to what Robert Kane has called 'the problem of intelligibility'. If in the exact same 'circumstances' where an agent might equally give expression to the state of her will though doing A or doing B, where A and B are two incompatible actions that satisfy incompatible rationales, then how do we account for such acts of the will that are thereby insensitive to reasons that may favor A over B (or vice versa)? We would have to imagine that the 'state the will' of the agent -- which presumably includes some degree of awareness of, or sensitivity to, the reasons that the agent has for acting -- resides outside of the 'circumstances' of the agent, where those 'circumstances' are construed by the contra-causal libertarian as to includes the agent's whole history down to the exact neurophysiological state of her brain.

    On my view, compatibilists are right to object to such a thin (and likely incoherent) conception of the agent and of her will such that they are not only free from the constraints that natural laws put on material processes but such that they can also act against them. Compatibilists rather (and more plausibly) seek to account for the features of the will in such a manner that, while it isn't so much as partially free from natural constraints, many of those 'constraints' aren't best construed as constrains on the agent's freedom but rather as rational or motivational constraints that the agent herself exerts on her own actions. She doesn't exercise them from outside of her 'circumstances', as the contra-causal libertarian would have it, but rather while still being subjected to the 'internal' circumstances that are partially constitutive of who she is as an embodied rational agent. Such 'internal circumstances' include some features of her history that have led to her acquiring practical rational deliberative abilities and some contingent set of motivations.

    So, when QM is being construed as providing some leeway into the broadly deterministic laws of nature, such that if the 'state of the universe' (or the 'state' of an embodied agent and of her 'circumstances') were to be rolled-back to some fixed earlier state, then, in that case, the agent might have acted differently, no satisfactory account is thereby provided of the freedom of the agent. And that's because of the aforementioned 'problem of intelligibility'.

    On the other hand, another feature of QM could have some relevance -- analogical rather than explanatory -- to the problem of free-will and determinism. And this feature has very little to do with the fundamental indeterminacy of the potential outcomes of measurement processes effected on quantum mechanical 'systems'. It rather has to do with the radical inseparability of the physical phenomena from the embodied and situated context within which those phenomena are being teased out from a determinate experimental set-up. It is because of this fundamental inseparability that it makes no sense to inquire about the actual position of an electron in the circumstances where the experimental set up has been established so as to measure its momentum. On that view, the very idea of the position of an electron (which is called an 'observable' in QM) is essentially relational rather than being a characterization of the intrinsic state of an individual electron. The position of an electron characterizes possible interactions of the electron with an observer which are only possible in a range of set-ups that are inconsistent with the observation of its (precise) momentum, and vice versa. So, attempts to characterize the electron's behavior deterministically, such that prior to having been observed it would already be disposed to manifest determinate positions and momenta, are attempts to separate the phenomenon from the circumstances of its constitution. This can't be achieved according to Bohr's or Heisenberg's interpretation of QM. On my view, hidden-variable or many-worlds interpretations of QM can be construed as attempts to rescue the metaphysical view from nowhere of physical reality such that quantum phenomena can be given non-relational descriptions that, however weird, still comport somewhat with our intuitions of the classical-mechanical universe: an universe that is populated with items that have the kinds of determinations that they have quite independently from the nature of our interactions with them. Both of those classes of interpretations seek to dispense with the essentially relational nature of quantum phenomena. They reflect attempts by the theorist to radically separate herself from the universe which she seeks to describe and explain from a point of view that abstracts (per impossibile) from her constitutive relations with the phenomena that she observes.

    I'd like to propose that both contra-causal libertarian accounts of free-will and most compatibilist accounts of free-will suffer from a defect that is deeply analogical to the 'metaphysical' (or 'realist') interpretations of QM. In the case of free-will accounts, though, the impossible task that is being attempted is the task of separating the agent from her world rather than the task of separating the observer/theorist from her world. Most compatibilist philosophers, on my view, only recognize partially the essentially relational character of agency since, unlike contra-causal libertarians, they acknowledge that parts of the 'circumstances' of an agent really are constitutive of who she is, as a radically embodied agent, rather than representing constraints on her agency which only operate 'from without'. On the other hand, they tend to theorize this separation between internal 'circumstances' (e.g. desires, values, reason) and external circumstances (knowledge, coercitions, physical limitations) from a point of view that is still a view from nowhere, and hence that allows from a deterministic psychology of the 'internal circumstances' of an agent. Because of that, I think, most compatibilists miss out on the nature of rational-causation, and of the autonomy of practical reason, as a neo-Kantian might conceive of them in irreducibly relational terms.
  • VagabondSpectre
    1.2k
    Unfortunately, (or fortunately (depending on one's existential footing)), the collapsing wave of quantum probability we find evident in fundamental particles refuses to grant us free wishes. If indeed the wave function plays a meaningful role in the goings-on of neurons, it would only wind up exporting its own 'randomness' into our mental constructs and processes. We would have hard random-will, and our thoughts could possibly move in pseudo-random "a-causal" directions; like Brownian motion.

    220px-Brownian_motion_large.gif

    Even if you can free your mind from the grip of determinism (unlikely), what then fills the causal vacuum becomes your new dictator: mere dice.

    Strictly speaking, quantum spookyness is still a mystery that needs more deciphering, and who knows, maybe Horton's soul is surfing an electron somewhere, but according to observation it's beyond unlikely. We think fundamental particles are the smallest possible units of matter, and if this is true it's good reason to assume that they're not individually animated by some intelligent force beyond themselves but instead by basic and seemingly universally applicable laws of physics which govern all things. Like when we roll a pair of dice, we presume that the basic and fundamental facts of the system govern the outcome of the dice roll, not the will of the roller; it would be nonsensical unless the dice were weighted, or unless you could roll with such precision so as to predict and achieve the desired outcome.

    I cannot tell you free-will isn't out-there somewhere, perhaps in a hitherto un-penetrated dimension, and maybe the collapsing wave function of quantum particle "spin" has something to do with how it mechanistically endows us with itself. I can tell you there's no evidence for it, there's evidence against it (not proof as of yet), and our willingness to see free will in the ripples is mostly our own wishful thinking.

    We found quantum dice that we cannot fully predict; an empirical black box. It may be a (de)-limitation of matter, or it might be a limitation of empirical science (local or global), and these dice rolls are happening everywhere, not just inside you. Electrons in nature entangle and collapse as a natural result of proximity, real world double slits cause interference in the position of quantum particles without us knowing or caring; the entire universe is oscillating at the fundamental - quantum - level with such frequency (perhaps) that we cannot measure it. And yet, out of the chaos comes an average stability; quantum particles tend to behave coherently, we find them more often in the position we left them in, and we can even guess the probability of finding a previously measured particle in a given new position; and we never find quantum particles doing the exact opposite of what they're told (if you orient an electron in a specific way, there's a 0% chance that when you remeasure its orientation (you orient it via measurement in the first place) that it will be in the diametrically opposite position).

    We may only ever find plausibly a-causal behavior in quantum particles, but it is evident that as particles begin to form larger structures, the noise of their quantum uncertainty is somehow muted. Atoms decay with some degree of uncertainty (AFAIK) but the average is very reliably measured. Molecules gain more stability and coherence still, and extended and extensive molecular and atomic structures make up most of the solid matter that exists at the human scale, and within which science has been magnificently successful at caging fundamental uncertainty.

    A final analogy: when an ant is following a pheromone trail and reaches a fork in the nose, it needs to make a decision about which trail to follow. It sniffs for other pheromones - signals - and it sniffs to determine which pheromone trail is thicker or fresher. It takes this information, performs a quick calculus, and carries on. Not all ants make the same decision in the same situation; some ants smell better, some ants are just rebels, but each ant makes decisions based on physical cause and there is widespread cohesion across ant-decision frameworks (there's an average that produces stability). If ants made completely random decisions they would also be making a lot of dumb decisions, and it would be foolish to think that every ant has a free-ant-soul that is looking out-and-ahead, and somehow informing thought and action. Verily, that the ant obeys its material and evolution-endowed structures, and that those structures are stable, is what allows ants to continue existing. Evolution can be cruel and certainly does roll dice, just not at the quantum level...
  • apokrisis
    4.3k
    So, can it be affirmatively asserted that QM affirms the concept of having a 'free will'?Posty McPostface

    The freewill problem arose out of the discovery of Newtonian determinism and its LaPlacean implications. So quantum indeterminism definitely challenges the Newtonian/LaPlacean paradigm that gave the freewill debate all its sociological charge.

    Noting of course that it was essentially a theistic issue anyway, as mind or spirit - representing organismic notions of autonomy or agency - were being opposed to science's mechanistic view of nature.

    But anyway. QM demonstrates that nature is essentially spontaneous. However it also demonstrates that this spontaneity is subject to constraints. Randomness or unpredictability always occurs in a context that is imposing some degree of limitation.

    So the deeper message of QM is not that nature is random and therefore nakedly free. It is that nature is the result of persisting constraints on such randomness. Thus if we are modelling something human like freewill, we should understand it in the same fashion - as the suppression of the unpredictable to the degree that it matters.

    In that light, it becomes natural that individual human choices occur in socially and environmentally pragmatic contexts. It takes those contexts for individual action to have a definite meaning, and not merely be random and meaningless.

    Now as a matter of freewill, you could choose not to wear matching socks. That might serve some sartorial purpose - one that means something, sends a definite signal to your social context. Or you might arrive at the same position by simply getting dressed in the dark and not checking. And that kind of sloppiness might also signal something to your social context.

    So freewill is a term that targets the kind of action which is thoughtful and purposeful as a considered response within the constraints of some larger social or environmental context. It says being an "individual" is about having enough autonomy to go with the flow, or go against the flow. But that counterfactuality is itself wholly dependent on some understanding of context.

    If you wear unmatched socks deliberately, you seek to signal your allegiance to some higher sartorial purpose. You definitely don't want to be mistaken for an actual, dress in the dark, rando. You most probably want to be granted the status of being such an autonomous being that you don't need to care that you might look like a rando. A complex game of social double bluff.

    [This example sticks in my mind because David Chalmers chose to wear one red sock, one blue sock, when he gave his first big audience talk on the explanatory gap/quantum consciousness schtick. And he is one socially crafty dude.]

    Moreover, human free choice would not be made possible by neuronal randomness in any case (and all the evidence so far seems to be against it) because no conscious human choice could ever operate to refashion neural networks directly at the neuronal level. Neural networks change through experience, not through will. — Heidi Ravven

    This is still seeking some kind of mechanistic account - the "experiential" weighting of syntaptic connects that determine an output state.

    Neural patterns need to seen as representing constraining contexts. They represent the information that limits the otherwise spastic operation of the body's many degrees of freedom.

    This constraints-based approach to autonomy is what neuroscience finds when it studies the development of skilled action.

    A beginner at a sport sends a confusion of control messages to their muscles. The result is a jerky and poorly timed action as the beginner winds up trying to push and pull at the same time. Skilled athletes have very quiet muscles when recorded with EEG. They are maximally efficient in limiting the spasticity or randomness in what their body would otherwise do.

    It is the same kind of story when recording the brains of babies as they learn to make perceptual sense of their world. It is all about learning meaningful neural constraint. At first, a neuron in the visual pathway will fire wildly in response to pretty much anything. But quickly it learns to limit its firing to some very precise kind of stimulus - like a line slanted at some particular angle. It learns to shut up the rest of the time.

    So brains - as neural networks - arrive at specific behavioural choices by evolving meaningful states of constraint.

    You as an individual could be doing anything at any particular moment - and what that would look like is the chaos of an epileptic fit. Luckily neural networks do learn from experience. They form useful interpretive habits. They form contexts that constrain the chaos to a pragmatic minimum.

    Randomness may still lurk. In nature, spontaneity is irreducible - as QM proves. But agency is about being able to suppress degrees of freedom to the point where any remaining variety is not a problem for the achieving of a goal. The irreducible spontaneity - the remaining quiver in the dart thrower's hand - is still suppressed enough that the goals are met. The bullseye gets hit often enough.
  • JupiterJess
    110
    So quantum indeterminism definitely challenges the Newtonian/LaPlacean paradigm that gave the freewill debate all its sociological charge.apokrisis

    Good post.

    But I think the many worlds stuff renews it though. Since that is completely (super?) deterministic and people have no will over which worlds they find themselves in. Consciousness trailing behind and the bottom up processes well ahead in front.
  • apokrisis
    4.3k
    But I think the many worlds stuff renews it though.JupiterJess

    Yeah sure. There are many interpretations that try to recover that lost determinism. You can go that route too. In the end, you can hide what you can't find out of sight, either as hidden local variables, or hidden entire worlds.

    So in desperation, you might believe absolutely anything to preserve your faith in the rule of physical determinism.

    Yet a constraints-based physicalism already explains the world better.

    And QM is moving towards that kind of interpretation with the quantum information or quantum reconstruction projects. MWI and Bohmian Mechanics are the last gasp of an out-dated way of conceiving of physicalism. Their advocates are especially passionate probably because they know they are a passing story. :)
  • VagabondSpectre
    1.2k
    Their advocates are especially passionate probably because they know they are a passing story. :)apokrisis

    Tut tut, my lad! :D

    Father Determinism may be on his death-bed, but grand-father Free-Will has been long since mourned!
  • aporiap
    102



    The levels of analysis that are relevant for making sense of CNS are neuronal, neuronal-population, and molecular. These can be mechanistically analyzed using newtonian mechanics no? I don't know why we'd need to use wave functions to model or describe a neuron or its macromolecular parts ...

    Ultimately we can say decision-making is mediated by neuronal population interactions, which are governed by laws of classical mechanics + some derivative chemical laws. All of those laws + knowing structure and functions of types of neurons and their parts within the networks they form allow for predictable and deterministic dynamics.
  • apokrisis
    4.3k
    These can be mechanistically analyzed using newtonian mechanics no?aporiap

    No.

    Well you can analyse them that way and discover nothing about what makes them tick.

    But if you are a neuroscientist, you might hope to decode what the patterns of activation mean by the way they correlate with observable behaviour. Which is analysing them semiotically.

    It is just the same as understanding some ancient writing system. Knowing everything there could be to know about how the marks came to be impressed on a clay tablet or scratched on a rock will tell you zero about what the marks meant to their makers. The physics of marks isn't the semantics of marks.

    Ultimately we can say decision-making is mediated by neuronal population interactions, which are governed by laws of classical mechanics + some derivative chemical laws.aporiap

    Hell no. Even the most reductionist of neuroscientists believes that you would need some kind of laws of information processing.

    As a machinery, populations of neurons may be ruled by some kind of standard syntax. And you might even use physical analogies as the inspiration for the kind of syntax that could work - like the "simulated annealing" popular as the kind of algorithmic constraint used in neural network modelling.

    But Newtonian mechanics has zip to do with it. The whole bleeding point of information processing systems is that those kinds of physical constraints don't have anything to do with it. You can't run a computer program on hardware that is flipping all its gates for merely physical reasons, like they are feeling too hot or too cold. Information processing works only to the degree the vagaries of the real world material processes have been shut out.

    So it is the other way round. For information processing to be predictable and deterministic, it must have the material world completely controlled.
  • JupiterJess
    110
    And QM is moving towards that kind of interpretation with the quantum information or quantum reconstruction projects.apokrisis

    Any links where I can read about this? (QM moving towards this view as opposed to MWI or alternatives?)
  • Posty McPostface
    5.1k
    I have read that neurons are composed of microtubules which obey the principles of QM indeterminacy. Penrose comes to mind in regards to this and his conception of how the mind works according to QM.
  • darthbarracuda
    2.9k
    You can't have free will if everything is random. That's not free, that's random.
  • Pierre-Normand
    1.4k
    But I think the many worlds stuff renews it though. Since that is completely (super?) deterministic and people have no will over which worlds they find themselves in.JupiterJess

    That is true, but somewhat misleading in the context of the free will debate, even granting, for the sake of the argument, the dubious metaphysical picture that underlies the 'many-worlds' interpretation of quantum mechanics. While an agent can't determine, prior to a quantum measurement, which 'world' it is that she would find herself into -- in which a single determinate measurement result is actualized -- from the set of all all the potential results (or 'worlds'') that had a finite probability of occurrence (or that she could find herself into) -- she can still control those probabilities by means of the prior set up. If she sets up Young's double-slit experiment, for instance, she can ensure that a photon (almost) never will strike the vicinity of a region of zero-amplitude on the receiving screen even though she will not control which one of the several bands with large amplitude the photon will strike.

    The more germaine question, then, is whether the agent can control the probabilities of the event that are occurring causally upstream of her own practical deliberative process. Libertarian philosophers are likely to demand that she ought to be able to do so. But it seems to me that compatibilist philosophers are right to deny there to be any need for an agent to be able to fully control such processes in order that her actions can be deemed free, and her own, in most of their relevant respects.
  • JupiterJess
    110
    This would be a good starting pointapokrisis

    Thanks a lot I'll look through them tomorrow :smile:
  • apokrisis
    4.3k
    If she sets up Young's double-slit experiment, for instance, she can ensure that a photon (almost) never will strike the vicinity of a region of zero-amplitude on the receiving screen even though she will not control which one of the several bands with large amplitude the photon will strike.Pierre-Normand

    And yet infinitely often, the zero-amplitude strikes will also happen in some worldline of the observer. Which screws any claim to have done something which has constrained the probabilities to these observed bands.

    Under MWI, there will be infinitely many worlds in which all the bands are composed of the least likely events. So the bands will be exactly where they shouldn't be for an infinity of observers.

    If you take MWI seriously, you can't take the probabilistic success of QM seriously. Everything that can happen, happens infinitely often.

    That's why you can't take MWI seriously.
  • Pierre-Normand
    1.4k
    Under MWI, there will be infinitely many worlds in which all the bands are composed of the least likely events. So the bands will be exactly where they shouldn't be for an infinity of observers.apokrisis

    The MWI is a metaphysical gloss on Everett's relative-state interpretation. Everett's own interpretation is somewhat anti-metaphysical inasmuch as its main philosophical import is negative. It consists in denying the metaphysical reality (local realism) with respect the alleged collapse of the wave function. It is still somewhat 'realistic' inasmuch as it achieves this denial though reifying the state vector associated with the observer and then accounts for the singularity of the measurement result though relativising (one-to-one) the projected states of the observed system to the corresponding projected states of the observer that it is interacting with. This yields the problem of the determination of the privileged basis for the projections of the combined 'oberver+system' super-system. Decoherence theories seek to solve this privileged basis problem by means of an appeal to the interactions with the environment but run into other problems while attempting to factor out the quantum mechanical descriptions of the composite 'system + observer + environment' in a principled way. (This problem is intractable and ill-conceived, it seems to me, mainly owing to its reliance on the possibility of an un-situated God-eye-view on the whole universe (or its state vector) as a theoretically 'pure' standpoint from which to effect the factoring out of this universe onto the three components: oberved-system, observer and environment.)

    The problem that you are raising for the MWI also arises within the framework of decoherence theories, but it seems to be mostly technical and relatively minor. If we don't reify the many-worlds as metaphysically real entities then we could account for the probability densities of potential quantum measurement (relative to 'observers') by means of coarse-grained descriptions of them. The main trouble with such interpretations, on my view, isn't so much the difficulty in accounting for the empirical verification of the probabilities derived from the Born rule so much as the ad hoc character of the definition of 'observers' (or or the 'worlds' of the MWI) seemingly devised for the sole purpose of rescuing metaphysical realism from the challenges posed to is by the profoundly relational character of the observables associated with quantum mechanical micro-physical 'states'. The realist interpretations seek to make QM palatable to the philosophically prejudiced theorist, with her 'classical' intuitions, but, in the process, obscure its most radically pragmatist implications.
  • apokrisis
    4.3k
    Decoherence theories seek to solve this privileged basis problem by means of an appeal to the interactions with the environment but run into other problems while attempting to factor out the quantum mechanical descriptions of the composite 'system + observer + environment' in a principled way.Pierre-Normand

    Quite. I am all for decoherence as the right general idea. It ties it all back to an emergent thermodynamical evolution in time.

    But you can't hide the basic metaphysical issue in an infinite splitting of the universe into tinier thermal compartments any more than by splitting whole worlds ... into infinite "world-lines".

    At some point you have to stop deferring the imposition of some limit, some cut-off. And once you accept that, you may as well turn around and start with the very thing of limits - ie: constraints - as your metaphysical primitives.

    If we don't reify the many-worlds as metaphysically real entities...Pierre-Normand

    ...then we might as well stick to Copenhagen minimalism.

    I think the historical issue here is that MWI has piggy-backed on the legitimacy of decoherence as a formal extension to quantum theory. The maths of QM got glued to the maths of statistical mechanics and a better model has resulted.

    But at the level of interpretation, MWI has smuggled itself in on the back of this. And for no special reason. Decoherence doesn't demand anything more than the epistemology of CI. And if your interest is in ontology, then MWI remains an extravagance and decoherence is essentially about thermal constraints on quantum indeterminism. We can now ask why coarse-graining would work.

    The main trouble with such interpretations, on my view, isn't so much the difficulty in accounting for the empirical verification of the probabilities derived from the Born rule so much as the ad hoc character of the definition of 'observers'...Pierre-Normand

    Yep. And so decoherence turns the environment into a generalised observer. Hierarchy theory can be applied to account for the effects of spatiotemporal scale. Simply put, at sufficient distance, any fluctuating process turns into a solid-looking blur. The quantum looks like the classical.

    So I object to MWI because it is business as usual for bottom-up constructive notions of ontology.

    Something has to put a lid on quantumness. We know the difference between the quantum, quasi-classical and classical states of being. It gets silly to pretend there is no kind of wavefunction collapse, even if it is an emergent decoherent illusion - what things look like at a distance - on the microscale.

    Given we have to accept constraints or limits and can't keep hiding the fact in inaccessible places, like an infinity of worlds or an infinity of thermal scales, then we might as well do the flip of treating constraints as ontically primitive. And that is how I understand the emerging quantum information approach - the reconstruction of QM that starts by ontologising probabilty rather than trying to defuse it via the unlimited worlds of modal realism.
  • aporiap
    102

    No.

    Well you can analyse them that way and discover nothing about what makes them tick.
    To my knowledge, the physics involved in modeling neural circuit doesn't go past basic EM and thermo. Wave mechanics of course for characterizing field potential fluctuation and action potential but not for modeling any properties or behavior of biological objects (macromolecules, neurons, neuronal populations).

    So no, not just newtons 3 laws but nothing 'special', spooky, nothing traditionally connoted with the colloquial understanding of quantum mechanics.

    But if you are a neuroscientist, you might hope to decode what the patterns of activation mean by the way they correlate with observable behaviour. Which is analysing them semiotically.
    You can probe a basic sensory system, layer by layer in something like drosophila and attempt to determine how stimulus information is represented within each layer. There are bottom up approaches that don't have the same inferential limitations as behavioral research.

    If by semiotic analysis you mean analysis of 'meaning' or what spatiotemporal patterns of activity within a set of cells represents then, of course that is the form of analysis or study that's commonly used. But the system is instantiated in a physical substrate so the 'symbols' of the referents are biophysical and biophysical principles need to be assumed in order to make sense of how those symbols relate to objective stimulus features


    It is just the same as understanding some ancient writing system. Knowing everything there could be to know about how the marks came to be impressed on a clay tablet or scratched on a rock will tell you zero about what the marks meant to their makers. The physics of marks isn't the semantics of marks.

    Understanding neural representation/semantics - isn't the only substantive project, it's just a fundamental requesite for any other kind of neural study. Biological mechanisms are what constrain and determine (1) the kinds of representation that can be had (2) decision-making process (3) valuation/value binding process (4) higher order brain process - decision-making, valuation/value binding process, attentional control, reasoning/inference making. You will need biophysical (and chemical) principles and design constraints to make sense of both semantic and mechanistic questions.

    Hell no. Even the most reductionist of neuroscientists believes that you would need some kind of laws of information processing.

    As a machinery, populations of neurons may be ruled by some kind of standard syntax. And you might even use physical analogies as the inspiration for the kind of syntax that could work - like the "simulated annealing" popular as the kind of algorithmic constraint used in neural network modelling.

    But Newtonian mechanics has zip to do with it. The whole bleeding point of information processing systems is that those kinds of physical constraints don't have anything to do with it. You can't run a computer program on hardware that is flipping all its gates for merely physical reasons, like they are feeling too hot or too cold. Information processing works only to the degree the vagaries of the real world material processes have been shut out.

    So it is the other way round. For information processing to be predictable and deterministic, it must have the material world completely controlled.
    There would be additional information processing laws but my point was that, within the biological context, 'initial conditions' - developmental precursor state + existing natural laws constrain the evolution in a way that the outcome is an adaptive, information processing system. CNS comes out of a self-guided natural process, ie deterministic play out of the precursor cells.
  • apokrisis
    4.3k
    Are neurons evolved to exchange signals or potentials?

    Let’s stop mucking about.
  • jkg20
    221
    This would be a good starting point - https://www.nature.com/news/physics-quantum-quest-1.13711
    Perhaps my reading is even more superficial than the article, but it seems to me that the new probabilistic approach being sketched in the article is just a vamped-up epistemology of QM, not a radically new metaphysical interpretation. It may end up predicting new experimental results and new ways of applying QM, but the metaphysics seems largely untouched.

    As for attempting to link QM and GR, for me that has always been based on a fundamental error in understanding GR. Gravity is a force under Newtonian mechanics. Under GR gravity is not a force at all, it is the manifestation of the structure of spacetime, and is thus not something that can be transmitted from one body to another via particles like gravitons.
  • Pierre-Normand
    1.4k
    Under GR gravity is not a force at all, it is the manifestation of the structure of spacetime, and is thus not something that can be transmitted from one body to another via particles like gravitons.jkg20

    Under GR the gravitational effects still are attributed to a field and to disturbances of this field by matter. This field just happens to be the structure of space-time in this case. The fundamental equations of GR are Einstein's field equations. They relate the metric tensor (characterizing the geometrical structure of space-time) to the source of the field (characterized by the stress-energy tensor, which registers the distribution of energy and momentum throughout space-time). So, the idea of a quantum theory of gravity is to quantize the field of gravity (that is, the perturbations in the structure of space-time) just as all the other fields are being quatized in quantum field theory. This is easier said than done, of course.

    You can thus think of the graviton as a quantum of excitation of the metric of space-time roughly in the same way as you can think of the photon as a quantum of excitation of the electromagnetic field. Of course, your intuition is correct that the graviton can't be correctly conceived as a point particle that is traveling through space-time and somehow interacting with it. But this naive picture wouldn't be correct as applied the the photon's relation to the electromagnetic field either!
  • Pierre-Normand
    1.4k
    ↪apokrisis
    This would be a good starting point - https://www.nature.com/news/physics-quantum-quest-1.13711
    jkg20

    @apokrisis By the way, there is a paper, which I haven't yet read, by Jean-Michel Delhôtel, discussing both Hardy's and Bitbol's approaches to the intepretation quantum mechanics: Quantum Mechanics Unscrambled.
  • apokrisis
    4.3k
    Perhaps my reading is even more superficial than the article, but it seems to me that the new probabilistic approach being sketched in the article is just a vamped-up epistemology of QM, not a radically new metaphysical interpretation.jkg20

    Yeah. Some say it is going back to CI. But for me, that is ontic in that it puts the observer - or at least, points of view - in the spotlight as the critical factor.

    So - as in Wheeler's participatory universe - the observer constructs the constraints that shape the probability spaces or wavefunctions. But this can't be human observers, so it must be some generic notion of an observer as the informational limits to constraint itself.

    The telling idea is that when it gets down to it, two opposing questions can't be asked of the same event simultaneously. Constraining the uncertainty regarding one of the variables results reciprocally in the loss of constraint on its complementary partner.

    So because "asking questions" = "constraining indeterminacy", the quantum information approach does suggest an ontology of an observer-created reality. Or to be Peircean, a pan-semiotic metaphysics.

    Bottom-up metaphysics starts with concrete events and then the weirdness starts when bare possibilities themselves become the concrete events. Everything that is possible also exists - leading to the need for the many worlds in which that concretely is the case.

    But I am talking about a top-down metaphysics where nothing is ever at base completely concrete, only relatively constrained in its indeterminacy. And quantum mechanics arises out of the impossibility of constraining states of affairs to the degree that two opposing questions can be answered with limit state accuracy in the same act of measurement.

    So the weirdness arises out of the limits that exist for top-down constraint - the quite logical limits - and not on assumptions about the concrete nature of bottom-up possibilities, which in turn require as many worlds as there are countable possibilities.
  • jkg20
    221
    But this naive picture wouldn't be correct as applied the the photon's relation to the electromagnetic field either!
    Nobody (as far as I know) has ever proposed a naive picture whereby a photon travels through the electromagnetic field. That would be a complete misunderstanding of electromagnetic theory. The naive picture, if there is one, is that the photon travelling through a region of spacetime is what constitutes the electromagnetic field in that region of spacetime. It is just here that the graviton as a particle model breaks down. The description of a graviton as a quantized part of spacetime (which I think is what you are getting at, but correct me if I'm wrong) makes perfect sense, at least if one allows that the structure of spacetime is discrete and not continuous, but the relation of the graviton to spacetime then becomes one of part to whole and the graviton is no longer a particle at all - it becomes a discretely identifiable element of the medium through which energy-bearing particles such as photons and gluons etc transfer their energy. However, one fairly standard picture of a graviton is to model it precisely along the lines of a photon insofar as it is also something that transfers energy from one part of space time to another, and that is the picture which I believe is fundamentally confused about what gravity actually is.
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