Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Chapter 8: Against Hume

  1. Apr 6, 2005 #1


    User Avatar
    Staff Emeritus
    Science Advisor
    Gold Member

    As we have seen in previous chapters, many of the central theoretical difficulties we have about phenomenal consciousness touch on the issue of causation in some way or another. Central among these is the problem of how our p-conscious experiences are related to our physical behavior, specifically our knowledge claims about the existence and character of p-consciousness. If we reject physicalism but do not wish to contradict our physical understanding of the world, it seems we are forced into some sort of epiphenomenalism where p-consciousness is relegated to being a superfluous feature of nature that plays no role in the world's causal dynamics. Epiphenomenalism is not a satisfactory answer to the question of how p-consciousness figures into the world's causal mesh, but it is not a trivial matter to reject it outright, since it seems we only arrive upon it by rejecting other views that are likewise unsatisfactory. Let us now consider this matter in more detail by reviewing the premises that build up to epiphenomenalism, and the possible responses to the epiphenomenalist argument. Here is how Rosenberg frames the argument (pg. 130):

    As Rosenberg eloquently puts it, "This argument creates a prism that refracts the different ways of placing consciousness in the natural order." If we deny premise (1), we wind up with either a reductionism that claims that p-consciousness can be reduced to physical phenomena, or an eliminativism that claims that p-consciousness does not even need to be explained because, in some sense, it does not really exist. We have already seen rejoinders to these positions in chapters 2 and 3. If we deny premise (2), we get nonreductive physicalism, which holds that p-consciousness and the brain are linked by some sort of primitive metaphysical necessity. However, it is not clear that such primitive metaphysical necessities can be at once meaningful and effective; a full critique of nonreductive physicalism and primitive metaphysical necessity is presented in chapter 3. Denying premise (3) commits us to either interactionist dualism or some sort of brute emergence supplemented with downward causation. However, there seems to be no empirical support on offer for either view, and they both seem to conflict with our theoretical understanding of physics. If we reject none of the premises, we wind up at some kind of epiphenomenalism or parallelism, whose problems we have already discussed.

    One route that has not yet been well explored is denial of premise (4), perhaps because it has been overlooked or perhaps because it has seemed too obvious to be worth challenging. Denying premise (4) would amount to claiming that, although a completed physics would afford us with a descriptively adequate chatacterization of the physical world's dynamics, it would still not be a complete account of the world's causal structure. This is precisely the line of investigation we will pursue in the coming chapters. To this end, we must engage in detailed considerations of precisely what causation is, and what relationship it bears to physical theory.

    Problems with Hume's View

    A good place to start in our philosphical investigation of causation is with the question of whether anything like relations of causal dependency, constraint, or production really exist among objects and events, or whether these are just human inventions that we project onto the world. The latter position was held by philosopher David Hume. According to Hume, objective causal connections among objects and events in the world do not exist. Rather, we humans merely project the notion of causal connections onto nature as a kind of psychological habit in order to account for the world's apparent regularities. So, for instance, a Humean view of causation might say that a dropped ball is not caused to fall to the ground by gravity or anything else; rather, falling objects just happen to have followed a pattern of regular behavior up till now, and this behavior has not been causally constrained by anything in any objective sense. A dropped ball may just as well float upwards as fall to the ground, then, as there is nothing 'forcing' it to do the latter. Let us call this view of causation the conventionalist view.

    The conventionalist view is surely counterintuitive; nonetheless, it has historically held appeal for some thinkers, particularly empiricists, since it dodges complicated metaphysical and epistemological issues of the nature of causal connections and how we could come to know anything about them. However, in recent years the conventionalist view has begun to fall out of favor, as substantial critiques have been leveled against it. For instance, it is not clear why we call only certain regularities 'causal'; it seems we cannot be realists about scientific truth or use physical laws as explanitory of observed regularities in nature if we are to be conventionalists; and, contrary to the Humean view, we cannot arbitrarily imagine any pattern of cause and effect holding between objects and events because in many cases, we define these things at least partially in terms of causal properties (e.g., 'father' or 'electron').

    In response to these serious objections, conventionalists have developed more sophisticated regularity theories that have "paralleled Ptolemy's astronomy, adding epicycle after epicycle to a poorly conceived theory" (pg. 133). Rather than engage these revisions, Rosenberg aims to knock down conventionalism at its roots. He presents a metaphysical problem and an epistemological problem for conventionalism, both of which arise only from the single premise that real causal connections do not exist among objects and events in the world. As such, these seem to be problems for any theory that denies the existence of real, objective causal connections in nature.

    The Metaphysical Problem: The Unity of the World

    The world is unified in the sense that there are many phenomena which are part of it, and that these phenomena can be meaningfully compared and related to eachother within it, e.g. along the dimensions of space, time, mass, motion, etc. What natural condition allows for the observed unity of the world? What allows things to be meaningfully related, and what is the condition upon which we can say something is or is not in our world? It is intuitive to appeal to causation and causal closure to account for this unity. For instance, we might say that all events causally descended from the Big Bang are those which reside in our world, and all other events lie outside our world; likewise, we might say that it is the causal connections among events that allow them to be meaningfully compared and related.

    But conventionalism sweeps the rug out from under this proposal. According to conventionalism, causal facts are constituted just by the regularities we observe in the world, and so in this sense, unity precedes causation for a conventionalist. Thus, conventionalism cannot appeal to causation as the unifying condition of the world without falling prey to circular reasoning, and must find some other way to account for the world's unity.

    In fact, things appear even worse for conventionalism when we consider that such a view seems to readily imply a completely disunified world at the outset, where all events are fundamentally isolated from eachother and 'blind' to eachother's existence. What prevents us from regarding each such atomic event as its own self-contained world, rather than a component of a much larger one? What establishes an overarching temporal framework in which these events are ordered? Rosenberg calls this the Humpty Dumpty problem: given such a disjoint set of events, how can we theoretically put them back together again to resemble the world we actually live in?

    A conventionalist might be tempted to appeal to a reified spacetime as a natural structure that establishes an inclusion condition for the world and the temporal succession of events. But appealing to the arrow of time to establish the latter is not an option for a conventionalist, as the time dimension has no inherent direction beyond that which is specified by causality. To salvage the appeal to spacetime, a conventionalist could assert that time achieves direction extrinsically, e.g. as a consequence of the lawfulness of increasing entropy as one proceeds away from the time dimension's low entropy extremity, as described by the second law of thermodynamics. But if such a lawful distribution of properties confers directionality to time, there is no principled reason why the same sort of thing could not occur for any of the spatial dimensions. Thus, the conventionalist's account of time's extrinsic directionality is not effective, as it only raises substantial further questions: Why do the extrinsic conditions that give time a direction hold, and why don't analogous conditions hold for any of the spatial dimensions? What is so special about time?

    The Epistemic Problem: Solipsism of the Present Moment

    Consider again the Humean notion of events. All events in the world, according to Hume, are free of any causal constraint; they are insular phenomena that are completely independent of and unaffected by eachother, not unlike Leibniz's windowless monads. What happens when we consider the mind as just such a monad or complex of monads, without supposing the existence of Leibniz's benificent God to direct their behavior? Rosenberg argues that we lapse into a profound skepticism where the only thing we can claim to know is the present moment.

    The basic reasoning behind the argument is that 1) if events do not causally constrain eachother, then they cannot share information, and 2) if an epistemic agent EA cannot gain information about a set of events E, then EA cannot know about E. Given the Humean premise that present events do not causally constrain future events, it follows that we cannot know the future. Given the additional assumption that future events do not constrain present events (and thus that present events do not constrain past events), it follows that we cannot know the past. Given that perceptual events at time T are about external events that occured at some time T-k in the past, for some measurable interval k, it follows that perception is about past events; and as we cannot know the past, it follows that perception cannot give us knowledge of external events.

    Thus, we have arrived at a radical and untenable skepticism where we cannot know anything about the future or the past, and we cannot even rely on perception to give us knowledge about the external world. We have been forced into a kind of solipsism where the only thing that escapes our global skepticism is knowledge of our own minds at the present moment. If our mental events are correlated at all with any external events, it is only by improbable coincidence, and so we still could not consider ourselves to know about these external events.

    After considering the metaphysical and epistemic problems for conventionalism, the view has no legs left to stand on. After all, Hume initially proposed the view in order to avoid problematic metaphysical and epistemological questions that arise from being realists about causal constraint, but being anti-realists about causal constraint only leads to far more severe metaphysical, epistemological, and explanitory difficulties. We are left with a picture of a fractured, disunified world (or a unified world whose unity we cannot explain) in which we must succumb to global skepticism; furthermore, we cannot explain the world's observed regularities and cannot account for the successes of science. If these objections hold, it is clear that we must reject conventionalism and be realists about causal constraint.
    Last edited: Apr 6, 2005
  2. jcsd
  3. Apr 9, 2005 #2


    User Avatar
    Homework Helper

    I haven't read this chapter yet, and I'm not completely familiar with Hume's views, but from the summary it seems like Rosenberg is just arguing that our universe is driven by causes as opposed to random change that happens to look like order by some unbelievable coincidence. If this is all he talks about, I think I'm going to skip this chapter, as that was already pretty clear to me.
  4. Apr 10, 2005 #3
    I have not read this book and, for that reason, I have not commented on it; however, after reading StatusX's rather caviler dismissal of the possibility that causality is entirely in our heads, I felt a strong urge to comment. In order to be in line with the discussion I thought it reasonable to give my conclusions (conclusions based on my adamantly ignored discoveries) as to the correct reason why the arguments given are wrong. :smile:
    Isn't it rather presumptuous to assume the current understanding of physics is correct? The most haloed academies of the past have certainly promulgated erroneous "facts". :wink:
    Now I have had the standard training required to obtain recognition as a Ph.D. in theoretical physics and know quite a little about the theories and the mathematics behind those theories. In my life I have never seen a physical phenomena which required the concept of causality to be valid. It is rather a convenient rule of thumb to maintain a statistical representation of the past allowing us to make statistical predictions of the future. Apparently my view is very similar to Hume's. Except that, as opposed to his philosophical position, I can analytically prove my assertion in detail. o:)
    I would differ there; it is quite a bit more than a habit, it is a unique solution to a profound record keeping problem. :cool:
    Well, I am sorry but I can prove that "a dropped ball" will not float upwards in a gravitational field, and I can do that without ever imposing a constraint of causality on reality. :approve:
    Hume's view is the "conventional" view? Or am I misunderstanding you? It's nice to have someone agree with me on something. :!!)
    The problem here is that almost all definitions extant are created via intuitive methods and, as such, are not at all carefully defined. Exactly the same thing is often defined in multiple ways; the consequence of that is that subtle specific relationships are inadvertently required to be true in order to remove inconsistencies created by those definitions. :rolleyes:
    If there is a problem, it would be a serious problem indeed. I will look at these carefully. :shy:
    That's easy, it's a figment of your imagination. It is the central requirement of a solution to that "profound record keeping problem" I spoke of. Without a unified perspective, the problem of record keeping isn't solved; you might as well just remember all the individual events. o:)
    Another easy question, the condition is very simple. Two possibilities exist: it is either something which is actually "in our world" or it is a figment of our imagination which is necessary to provide the unity spoken of above. o:)
    Yeah, it sure is; but that is certainly not a defense for asserting such a thing. All I see so far is your desire to maintain "causality" as a real phenomenon. :grumpy:
    The most obvious solution to this apparent dilemma is that what you are trying to account for is a figment of your imagination. :biggrin:
    Do you really want to know how? I can show you if you would really care to listen. :cool:
    What bestows order on time is our own imagination (again, a piece of that unique solution to the record keeping problem) the past consists of what we know, the future consists of what we don't know. Time becomes nothing but a parameter tagging that portion of the record keeping problem (it's called change). What it means is that you have not yet solved that profound problem: i.e., if you don't know everything it means what you know will change. Thus, either you know everything or change will occur and that fact is an intimate part of your problem of understanding what you know. :wink:
    What is special about time is that it's a product of your imagination (a illusion) the purpose of which has not been comprehended by your logical conscious thought. :rolleyes:

    So "The Metaphysical Problem" problem appears to be a figment of your imagination and I will proceed to "The Epistemic Problem". :shy:
    And, prey tell, how could one hope to know that (under the presumption that he means "really know" and not "think he knows"). The problem here appears to be exactly the issue I brought up to Canute here. It is very important that one realize that there exists a need to differentiate between "what we know" and "what we think we know" before we have any method of separating the two. Just because we cannot separate the two does not require that we do not really know some things: i.e., not being able to prove we really know something is not proof we do not really know it! We may actually know some things. The difficulty is we do not know what we know and that is a real fact which our reasoning must take into account. o:)
    As far as I am concerned, we absolutely cannot "know" the future as I define the future as "what we do not know". Our best bet is to presume it will statistically resemble the past (the past being what we know and that would be what we really know and not what we think we know). Do you comprehend why these two concepts need to be separated? :confused:
    Now I have to disagree with that as I define the past to be what we know. And lastly, "perception" is part of the solution, not part of the problem: i.e., another illusion created to explain change in what we know. :smile:
    You did; but I didn't. :rofl:
    The real source of your dilemma is the fact that you presume that either everything you think you know you really know or it's all an illusion. You simply have not considered the situation where some of what you think you know you really know but much of what you think you know is mere illusion. You presume your inability to prove what you do and do not know demands one case or the other. :grumpy:
    Isn't the real difficulty here the fact that the two positions "realist" and "anti-realist" reside in the "we can't prove that" category? :devil: As I said, "it is very important that one realize that there exists a need to differentiate between "what we know" and "what we think we know" before we have any method of separating the two. You are attempting to make the separation first. :yuck:
    Yes, you are left with a fractured disunified picture and that itself should be sufficient evidence that you are wrong. And your solution, "be realists about causal constraint" is the wrong answer. :yuck: again!

    Have fun -- Dick
  5. Apr 12, 2005 #4


    User Avatar
    Staff Emeritus
    Science Advisor
    Gold Member

    Doctor Dick, it appears you misread me in a few areas, judging by some of your responses. However, I'd like to keep this response as brief as possible in order to make any attempt at discussion tractable, so I'll limit this post to the major issues.

    How? If it is guaranteed that the ball will never float upwards when sufficiently close to Earth, then by definition there is some constraint on possible ways the ball may act, and that constitutes causality.

    On the metaphysical problem:
    You claim events are ordered in time according to our imaginations, and that the past is what we know and the future, what we don't know. This is a rather fantastic claim, and you've offered no justification for it. There also appear to be some deep problems here. For one, we cannot plausibly identify the past with what we know, as we only know a remote fraction of what has occurred in the past. For another, by what non-temporal agency does our knowledge continually grow? You refer to things like imagination and knowledge, but these are processes firmly embedded in a temporal framework. The metaphysics of your proposal seems not just outlandish, but outright incoherent.

    On the epistemological problem:
    It does not seem you've actually addressed the argument here at all, except to state that the conclusions disagree with your definitions, and therefore must be wrong. The epistemological problem arises from observing that we need some metaphysical mechanism by which we can come to acquire knowledge of the external world. A Humean world with no causal connections provides no such mechanism, and nor have you.
  6. Apr 17, 2005 #5
    A problem concerning the epistemic problem

    In my opinion the argument trying to show that the humean theory of causality leads to solipsism faces a problem in logical structure.
    The problem lies in line six (p.138). In normal speech it would be necessary to say: “Present events were the future events of (now) past events. Therefore you need to explain the logical shift from present tense to past tense and vice versa and if that shift causes logical consequences to the argument.
    I think it causes a problem, because of different connections between past-future and past-present. The “causal” paths between past and present events are already fixed and therefore it is possible to know, how the observed system behaved at a certain past time. That is not the case for future events. I suppose that changing the temporal level destroys the logical structure of the argument and needs further explanation.
    Last edited: Apr 17, 2005
  7. Apr 18, 2005 #6
    I have no comment on this chapter and no particular disagreement with it. However I thought that these two arguments below were interesting read side by side. Schroedinger accepts most of the first argument, for epiphenomenalism, in his first premise, or so it seems to me. But he also accepts his own experience of consciousness, and thus reaches a rather different conclusion.

    1. The physical facts alone do not entail the facts about conscious experience.
    2. We can conclude, from (1), that
    2'. Experience is a nonphysical aspect of the world.
    3. A completed physical theory is, in principle, a descriptively adequate characterization of the dynamical evolution of the physical world.
    4. We can conclude, from (3), that
    4'. Our physical explanations are complete explanations of the causation involved in producing bodily movements.
    5. We can conclude, from (2') and (4'), that
    5'. Consciousness lies outside the causal structure of the world, that is, it is an irrelevant epiphenomenon.

    "Schrödinger encapsulated the problem of consciousness in the form of two premisses:

    · My body functions as a pure mechanism according to the laws of nature.

    · Yet I know, by incontrovertible direct experience, that I am directing its motions, of which I forsee the effects, that may be fateful and all-important, in which case I feel and take full responsibility for them.

    To avoid a contradiction here, he said, ‘the only possible inference from these two facts is, I think, that I – I in the widest meaning of the word, that is to say, every conscious mind that has ever said or felt "I" – am the person, if any, who controls the "motion of the atoms" according to the laws of nature.’ … [t]his would lead you to say, Schrodinger provocatively suggested, ‘Hence I am God almighty’."

    Editors’ Introduction
    The Volitional Brain
    Towards a Neuroscience of Free Will.
    Ed. Libet, Freeman, Sutherland
    Imprint Academic (1999) (p xvii)
    Last edited: Apr 18, 2005
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook